Some ZS167FML questions for racing sidecar

[Jibberwobble]

Hi again

Well after a rather longer than expected interlude dealing with life's little obstacles it's time to have a look at the engine in my little sidecar (pushrod CG clone) and see if it will go any better with a bit of tickling!

We have now done three rounds of the British championships with my Zong powered outfit and we are looking quite competitive. There are 10 or 11 outfits in our grid and we run in about forth position usually which I'm pretty pleased with to be honest considering the norm is to get lapped every race for most of the first season.

The engine has run very well so far but is needing a little more power on the straights. The others are running various 80/85cctwo stroke moto-x engines, CB125 bottom ends with 160cc barrels or CRF150 four stroke Moto-x units. We have the least power out of all of them But for some reason I have come to like the Zong and would like to give it a fair crack of the whip before disregarding it as not good enough for the job. If I cant get it up to speed I will consider a different chinese engine before going Jap.

One point that is going to make engine development hard to measure is that the damn thing wont fit on any dyno I've come across yet! One way or the other the zonger needs to be putting out 20+ HP and ideally 22HP would be nice. I'm not sure this is ever going to happen though.

Currently I have a new exhaust going on soon and need to get onto checking the valve clearances before the next round in two weeks. Also got a big list of other mechanical issues to resolve.

So for some questions about these engines.......

I am running a 27mm mikuni, I want to try something bigger but what is too big? I'm thinking either a 30 or 32mm?? also a Carb that is not so tall as the Mikuni would be handy as it currently very in the way and stopping my laying down properly on the outfit. In addition I am considering a custom manifold to get the carb down lower but not sure how long the manifold can be before it starts to effect atomisation and power?

Is the clutch on these engine usually VERY stiff? It's definitely not the cable.

I need to have some gearing options, I am on 17-front and 24-rear (using 11" kart tyres (tires-american)). How big will I get away with on the front? Having an 18 and a 19 would be good but not sure they will fit. Cant find anything bigger than 17t for the Zong so is there a jap engine with the same shaft dimensions so I could buy a quality sprocket or two to fit?

Does anyone have any output figures from one these engines with all the restrictive rubbish removed?

Should I stick with standard Zong CDI's or is there a Honda etc variant that is the same or better?

Same as above for coil?

Anyone messed with valve timing?

[Weldangrind]

So many questions!

Before we begin, what is the actual displacement of your pushrod motor? Are you limited by displacement in your racing class?

This is the carb I like for 200 / 230 China motors: http://www.ebay.com/itm/Carburetor-Carb-ATV-Dirt-Bike-Quad-Honda-MIKUNI-30mm-/221162076630?pt=Motors_ATV_Parts_Accessories&hash=item337e4979d6&vxp=mtr I jet them with a 112 main and 27 slow at sea level for a 200, 115 / 30 for a 230.

This is the intake tube I have on my atv: http://www.ebay.com/itm/30MM-MANIFOLD-INTAKE-MIKUNI-CARB-ATV-CRF-XR-50-XR50-70-/300160864696?pt=Motorcycles_Parts_Accessories&hash=item45e2fb51b8&vxp=mtr Not sure if it costs any power, but I doubt it. The air and fuel are happily sucked uphill by engine vacuum.

The clutch isn't normally that difficult; certainly no more than an average CG125. If you can't find a mechanical problem, perhaps this would help: http://www.ebay.ca/itm/Chrome-Hydraulic-Clutch-Lever-Cylinder-Motorcycle-Dirt-Bike-ATV-1200MM-GO-KART-/151050257970?pt=AU_Motorcycle_Parts_Accessories&hash=item232b4c0632&vxp=mtr

You're using a 17 tooth countershaft sprocket and a 24 tooth rear sprocket? I can't believe that little motor can use such tall gearing. I figured that 40 teeth would be the outer limit for a rear sprocket.

I would certainly try a racing CDI, or even a programmable unit.

I've never messed with timing. I would focus on smoothing the intake port and polishing the exhaust port first.

[Jibberwobble]

Thank you Weld.....

Just popped in and gotta rush off again so will be back later to reply properly but in answer to the gearing thing, I am running an 11" kart rear tyre instead of a big bike wheel and this will bring the gearing right down to something nearer the norm. We are pulling about 60MPH on the long straights at tracks that are about 1.2km all the way round.

It's a 200 which is the displacement limit for a 4 stroke in the regs. 85cc for a two stroke.

[katoranger]

I don't know if anything bigger than a 17t will fit. You may have to drop a tooth on the rear.

[Jibberwobble]

The trouble I'm having with gearing is that I'd like to have options to go both higher and lower than my current setup. I have a tired 24t on the back and feel that a 26 would be nearer the mark for most tracks.

Because there is not much size difference between the front and rear one or two teeth on the back makes quite a big difference. Going up on the front and back will give me ratios that lay in between just going up in 2t increments on the back alone.

In addition the 24 I have on the back seems to be very rare and all I can find to fit a 30mm kart axle is 26/28/30 etc nothing smaller, so a bigger front would bail me out a bit.

Hopefully tomorrow or thursday I will get the chance to pull the cover off and have a closer look to see how much room there is.

So is there a common mass produced front sprocket fitment that will go on my zonger? Seen some Yam ones that look the same but havent laid my hands on dimensions yet

[Weldangrind]

I believe this is the JT sprocket that fits your countershaft: http://www.jtsprockets.com/catalogue/sprocket/JTF259 It only goes to 17.

[Jibberwobble]

So many questions!

This is the carb I like for 200 / 230 China motors: http://www.ebay.com/itm/Carburetor-Carb-ATV-Dirt-Bike-Quad-Honda-MIKUNI-30mm-/221162076630?pt=Motors_ATV_Parts_Accessories&hash=item337e4979d6&vxp=mtr I jet them with a 112 main and 27 slow at sea level for a 200, 115 / 30 for a 230.

This carb looks good, does it bolt straight to the engine or are the holes a different pitch? Just a thought because if it were sitting that close to the engine it may not get in the way too much.

This is the intake tube I have on my atv: http://www.ebay.com/itm/30MM-MANIFOLD-INTAKE-MIKUNI-CARB-ATV-CRF-XR-50-XR50-70-/300160864696?pt=Motorcycles_Parts_Accessories&hash=item45e2fb51b8&vxp=mtr Not sure if it costs any power, but I doubt it. The air and fuel are happily sucked uphill by engine vacuum.

Funny enough I've been watching that one for a while wondering if it's the answer to some of my problems, just going off to have a look through your threads for a picture of it fitted (assuming there will be one somewhere). Shipping to uk is a bit scary though.

The clutch isn't normally that difficult; certainly no more than an average CG125. If you can't find a mechanical problem, perhaps this would help: http://www.ebay.ca/itm/Chrome-Hydraulic-Clutch-Lever-Cylinder-Motorcycle-Dirt-Bike-ATV-1200MM-GO-KART-/151050257970?pt=AU_Motorcycle_Parts_Accessories&hash=item232b4c0632&vxp=mtr

Well when I compare my clutch lever resistance with other peoples I would say mine was around ten times heavier! I can pull most clutches in with a couple of fingers but with mine I need a good grip and most of my strength. Oddly I dont notice too much when we're out on track most likely due to Adrenalin. Havent had a chance to research how it all goes together yet but will have a look into it and go down the hydraulic route if all else fails. Thanks for the link :)

You're using a 17 tooth countershaft sprocket and a 24 tooth rear sprocket? I can't believe that little motor can use such tall gearing. I figured that 40 teeth would be the outer limit for a rear sprocket.

Indeed my tiny 11" tyre on 5" rim brings the gearing back down.

I would certainly try a racing CDI, or even a programmable unit.

Will have a look into this and try and find something. I'm a bit lost with the CDI's to be honest, is a 125 CDI different from a 200 and if so what does it do differently? I need a spare so will get scouting, I think it's a bit more of a struggle to find this chinese stuff in the uk and the unknown import duties bother me a bit when ordering offshore.

I've never messed with timing. I would focus on smoothing the intake port and polishing the exhaust port first.

Ok will have a peek into the inlet/outlet and see how they can be improved, this sort of thing is up my street. I can get 11.5hp from a 40cc w/c 2stroke with the aid of my trusty dremel and it's friends! Time consuming but satisfying.
I believe this is the JT sprocket that fits your countershaft: http://www.jtsprockets.com/catalogue/sprocket/JTF259 It only goes to 17.

Thanks, done a bit of looking now and have found some chinky ones (18t) very cheap that I think will fit the shaft so I will go for it and see if it fits in there, I'm sure it will be fine for experimenting.

http://www.fiddyparts.co.uk/index.php?page=shop.product_details&product_id=138&flypage=flypage.tpl&pop=0&option=com_virtuemart&Itemid=107

http://www.ebay.co.uk/itm/PITBIKE-FRONT-SPROCKET-18-TEETH-428-20MM-INNER-PIT-BIKE-SPROCKET-18-TOOTH-QUAD-/281105022523?pt=UK_Motorcycle_Parts&hash=item41732a3e3b

http://www.ebay.co.uk/itm/18-TOOTH-428-17mm-SPLINE-FRONT-SPROCKET-FOR-PIT-BIKE-ENGINE-/281121077886?pt=UK_Motorcycle_Parts&hash=item41741f3a7e

[Weldangrind]

The 30mm Mikuni bolts to an intake tube (of whichever style). I don't think you'd be successful without at least an insulator. This intake is free to ship to me, and I could always post it to you, if you wish. perhaps that would save a bit. http://www.ebay.com/itm/30MM-MANIFOLD-INTAKE-MIKUNI-CARB-ATV-CRF-XR-50-XR50-70-/300160864696?pt=Motorcycles_Parts_Accessories&hash=item45e2fb51b8&vxp=mtr

Bogieboy has experience with hydraulic clutches, so I recommend that you seek him out.

Different CDI's will have not only dissimilar amounts of advance, but also different rates. Humanbeing is our resident expert.

That's cool that you found 18 tooth sprockets. I wonder if you'll have clearance problems.

[Jibberwobble]

Whoops been all tied up for a few days pulling my old car to bits to sell as much as pos before scrapping it, it's funding the sidecar upgrades and spares.

Also been busy finding the right parts for the outfit and trying to get em all to arrive before this weekends race meeting. I've got so much to do before it's ready I'm pullig my hair out!

I now have the 18t front sprocket and it looks like it will work with a little relief to the cover.

I'm out of T-break now but will be back later with some pictures :)

[Weldangrind]

I now have the 18t front sprocket and it looks like it will work with a little relief to the cover.

Do you mean the sprocket cover? I'd just remove it completely; that's how we do it on dirt bikes.

[Jibberwobble]

Do you mean the sprocket cover? I'd just remove it completely; that's how we do it on dirt bikes.

You know what, thats a bloody good idea!

As it goes I will have to stick with it for now for safety reasons, My fully enclosing bodywork is not built yet and I have some very temporary bits of chopped up second hand fibreglass on there. Eventually the seat unit will go all the way up and over the engine enclosing the chain all the way from front to back, right now it's exposed at the front which is a bit iffy really although my legs have survived a couple of chain breaks and a derailment.

To get an idea of the riding position kneel on the floor with your knees 18inches apart and your toes pointing at the floor and your butt sat 6inches above your heels. The chain passes about 1 1/2 inches below your knackers and 3 inches inside you left thigh. In an accident it would be very easy for a flailing limb to say a little hello to the front sprocket and have a little go on the roundabout!

I've done a quick mod to get me by for now so we'll see how it goes this w/e.

Cant find a good photo of the seating position and chain run just now but you sort of get the idea from this

http://i82.photobucket.com/albums/j252/Andydw/Fab%20Racing%20Llandow%2031-3-13/524108_10152736454040228_1448084623_n.jpg

http://i82.photobucket.com/albums/j252/Andydw/Fab%20Racing%20Llandow%2031-3-13/67210_10152736486005228_759428152_n.jpg

So with the 17t sprocket roughly placed in the cover you can see the clearance situation

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1476_zpsa8b3527d.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1476_zpsa8b3527d.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1473_zps3a3be538.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1473_zps3a3be538.jpg.html)

And the mark on the inside of the cover, I think this happened on a joining link break. We now have a new chain and will be rivetting it. There were various other issues causing chain troubles and most of the worn out and poorly set up parts have been replaced with new now. Axle, bearings, chain, front and rear sprockets, break disc and carrier all replaced.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1479_zps82745c47.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1479_zps82745c47.jpg.html)

Chop chop!

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1487_zpsee31db94.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1487_zpsee31db94.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1488_zpsa388582d.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1488_zpsa388582d.jpg.html)

Very thin peice of Carbon sheet is now giving me another few mm of clearance.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1499_zps114c3803.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1499_zps114c3803.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1500_zps9ae1520f.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1500_zps9ae1520f.jpg.html)

And with the 18t in place it all gets a bit tight but I think just about doable.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1485_zpsbcf0a4c2.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1485_zpsbcf0a4c2.jpg.html)

[Jibberwobble]

The 30mm Mikuni bolts to an intake tube (of whichever style). I don't think you'd be successful without at least an insulator. This intake is free to ship to me, and I could always post it to you, if you wish. perhaps that would save a bit. http://www.ebay.com/itm/30MM-MANIFOLD-INTAKE-MIKUNI-CARB-ATV-CRF-XR-50-XR50-70-/300160864696?pt=Motorcycles_Parts_Accessories&hash=item45e2fb51b8&vxp=mtr

Bogieboy has experience with hydraulic clutches, so I recommend that you seek him out.

Different CDI's will have not only dissimilar amounts of advance, but also different rates. Humanbeing is our resident expert.

That's cool that you found 18 tooth sprockets. I wonder if you'll have clearance problems.

The clutch and CDi will have to wait for the minute, just need to get through this w/e and once the dust has settled I'll attack these issues and search out these two guys for some of their wisdome. Thanks for pointing me in the right direction.

Will also get back onto the carb and manifold, I need to have the carb finalised before I can build the seat unit up.

[Weldangrind]

You're a tortured artist, aren't you? That sprocket cover looks as if it was cut on a milling machine. Those tubing bends are beautiful; do you have a mandrel bender?

[Jibberwobble]

You're a tortured artist, aren't you? That sprocket cover looks as if it was cut on a milling machine. Those tubing bends are beautiful; do you have a mandrel bender?

Thanks for your kind comments but it actually looks quite grewsome in the flesh! I just used a hack saw and barrel grinder to do the casing. The bends are done with a Hilmor pipe bender similar to the one pictured below, for the heavy duty hydraulic tubing it can be a family effort with the my good lady and kids hanging off the frame whilst I hang off the end of my trolley jack handle like a gibbon in a tree.

http://hirehere.ie/image/cache/data/con%20bender-500x500.jpg

It all got very busy at the end of last week getting ready for the race meeting and the last of the parts I ordered arrived just in time. We had a good laugh on track and once again battered the bodywork bouncing off our sparing partners, really need to get some video. Loads of teething troubles with new parts and set up issues but the 18t front pinion and gear ratio change worked very well with no problems.

Before the meeting I changed the exhaust from a stock 400cc CBR to a 600cc Micron performance exhaust with a 35mm outlet. I did this because the old exhaust was getting quite broken and the new one was given to me. Being much less restrictive I suspected a jetting change would be needed and was indeed not wrong. On our first out lap it felt a bit gutless and got very hot, the plug had a tinge of white around the shoulder of the electrode so I went on the hunt for a bigger jet. We had a 120 in there (Mikuni VM27) and all anyone could come up with was a 150! it was worth a go as the sun was beating down and everything was hot, and my Zonger was gonna cook on that 120. with the 150 the engine felt less strangled but as you would imagine it got half way up the rev range and started to splutter and was avoided by a short shift in every gear. By the end of each session it had surprisingly almost cleared though. Eventually found a 130 jet which I think is still a little lean but it got us through and we finished 5th, 4th and 3rd respectively in our three races despite not being able to find 5th gear half the time.

Back soon to address some of the issues.........

[Weldangrind]

I have a numbered drill bit set that I've used for quick jet size increases. Sometimes you're in a situation where you simply can't get the jet you need, so a drill bit is the next best option.

Please show us pics of the new exhaust.

[Jibberwobble]

I'll sort a photo today.

Yes I have a nice selection of small drills but didnt have them with me. I know jets are supposed to be more than just a roughly drilled out hole but as you say in desperate times these little tricks can get you out of the dog doo.

I'm going to head for a selection around 140 kinda size which seems rather huge to me but hey! If I can get it on a dyno with lambda sensor I'm sure it would be a quick excersize to get it right.

Also do these gearboxes play up when very hot? There's a number of other small issues with the gear change that could be messing it up but sometimes not even a running drop kick would get it into 5th.

[Weldangrind]

They certainly can. With punishment like you dish out, I'd probably try synthetic 20W40.

[Jibberwobble]

Bloody hell time flies, I need a time machine! Life got in the way again.

At the last round we settled on a 135 main jet after a 137.5 showing just a hint of over rich at the end of the straight. we are lapping a little quicker now and only half a second or so behind the quickest lap of the weekend, with a small power increase we will be right up there at the sharp end.

The bodywork is completely fubar now after a visit into the scenery and burying the front end in the tyres to the point where the bodywork was squashed flat onto the forks and breaking the front brake lever off. Going to have to blob it back together for the one remaining round this year.

The gearbox worked without fault all weekend.

The exhaust is not very pretty but hasnt snapped off yet dispite breaking an engine mount thumping the chair wheel over the curbs. If you get it right the chair wheel is up in the air before reaching the apex and completely clears the curb.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1555_zpsfbf3ef47.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1555_zpsfbf3ef47.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1553_zps0d6ab51c.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1553_zps0d6ab51c.jpg.html)

I stopped looking for a carb after a 32mm unit came my way, unfortunately when I came to start looking at dealing with the manifold I realised it wasnt a 32 at all but was a 28. I feel I need to go up to at least a 30mm so will get back on it soon. Been told that the longer u-shape manifold that I have planned will be good for bottom end torque which is a good thing as pushrod motors are never gonna be screamers.

Hoping to make some updates and repairs over the w/e to the old bucket.

[Weldangrind]

That exhaust looks pretty good from my perspective!

I've been giving some thought to a perfomance cam for the pushrod motors, and it occurred to me that reducing the base circle would have the same effect as increasing lift. Do you know any old-school machinists who could grind a cam for you?

[Jibberwobble]

I had a similar thought myself after remembering doing something like this as a teenager on an old honda engine in a go kart, my mates dad helped me out, he built vintage racing Austin Seven's for a living. I do have a couple of potential candidates to do such a job so it can go on the further investigation needed list.

Cant decide if a 32mm carb is too big or just get a 30 like the one you pointed out. There are KOSO 32's (Keihin clone) on ebay uk for a good price, not sure if a chinky carb is the way to go though hmmm!

https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-ash4/285393_4701164386892_1973650888_n.jpg

https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-ash4/1173790_4701168346991_1111800453_n.jpg

https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-prn2/1187215_4700637213713_580070597_n.jpg

[Weldangrind]

That last pic is priceless! "I've knocked a bloody filling loose!" :lmao:

[katoranger]

I don't think I want my head that close to the ground.

[SpudRider]

I don't think I want my head that close to the ground.
X2! :hehe:

[Jibberwobble]

Me again.....

Chad (my passenger) has quite a few grazes on the top of his lid now! I remember when I was passengering, the grass would be whipping the top of my helmet and visor with the sky visible by looking down not up. The problems start when the outfit behind makes a late lunge up the inside, hits you and takes your passengers head off. I like my passenger with his head on, its made of solid oak and the low down ballast is very usefull :)

Just sorting some photos..................

[Jibberwobble]

OK done a little work with the carb side of things, after sorting through some boxes of hoarded junk I came across some lengths of nicely bent ally tube with 28mm ID.

After some investigation, the carb I have been running would appear to be a Mikuni TM28 although it actually measures 27mm at the venturi. The other one I have been donated is a Keihin PWK28 and is 1mm larger. As far as I can tell the PWK is a two stroke carb but so I think is the TM28 I'm already using which runs very well.

However the PWK (pictured below) is physically smaller even though it has an extra 1mm venturi so is the preferred choice out of the two due to the carb being in the way where ever I put it.

Have measured the intake port of the engine and it's also 28mm so I'm thinking to just get by with one of these 28mm carbs for the last round and do some manifold experiments to work out if I'm on the right track before enlarging everything including some work to the intake and exhaust passages.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1654_zpsfca40004.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1654_zpsfca40004.jpg.html)

So I have chopped up some sections of tube and eventually found a shape that puts the carb in a place that less bad than everywhere else I've tried it. I dont know if this manifold will be too long though so have temporarily joined the bits together with some semco hose for trials. The manifold could be shorter with the carb behind the cylinder but would require some impossible bends!

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1655_zps320f30a7.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1655_zps320f30a7.jpg.html)

Here you see the TM28 sitting where I've been running it on a tight elbow manifold and the new trial manifold heading off in a new direction.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1656_zps502764ea.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1656_zps502764ea.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1658_zpsa65feaac.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1658_zpsa65feaac.jpg.html)

[Weldangrind]

I'm interested to see the final placement of the carb. Do you intend to have the tubing TIG welded?

[Jibberwobble]

Not sure what is best really? weld the middle yes, rubber sleeve on the carb end obviously, engine end is a quandry. I'm thinking the tube may be a little on the light side to put up with the vibration and jarring.

As it happens the OD of this tube is 32mm so I could potentially use it as a pattern to mould a CF heavy weight tube for a bigger carb once the inlet has been relieved to the same size.

This is with the TM carb that I've been using. if it runs ok with this one I'll put the PWK on as it's physicaly smaller and will be less in the way.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1661_zps5b9b5fbe.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1661_zps5b9b5fbe.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1663_zps98fac742.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1663_zps98fac742.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1664_zps7c2a80b3.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1664_zps7c2a80b3.jpg.html)

[Jibberwobble]

A little development.

Had a tidy up of the birds nest of wiring thats been cable tied to the battery all year, now lives in a little CF box I made along with a battery tray (still to be secured). Gotta admit I dont understand the wiring, red wires turn into black wires, yellow and green connect to red, and yellow and red connect to green etc etc!! I'm sure the guy that chopped this loom up and attached it to this outfit in it's previous life commented that some things like the on/off switch were working backwards so he changed some things around. It all works though so have just connected it all back the same but in a slightly more organised fashion. Moved to coil and rectifier out of the way too.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1671_zps62e251fd.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1671_zps62e251fd.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1706_zps737aadda.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/IMAG1706_zps737aadda.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/Minimoto%20Sidecars/My%20outfit/f95aaf08-d6f4-4def-8402-f08ee50c9254_zps2be8b75e.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/Minimoto%20Sidecars/My%20outfit/f95aaf08-d6f4-4def-8402-f08ee50c9254_zps2be8b75e.jpg.html)

Right so I've tried running the engine with the long manifold. It runs but needs some fiddling. This carb has always suffered a bit from a cloud of mixture/vapor chuffing back out of the carb mouth at wide open throttle and it seems to be worse now with the cloud reaching out in front of the handle bars, I can also feel it cooling my hand on the throttle grip as it passes by. I can pretty much pin the throttle with it in neutral and the engine doesnt reach very high revs so the first hunch is that it's now running much richer than it was with the short manifold. Secondly I think I should try disconnecting the power jet pipe on the TM28 carb. I'll have a play with it tomorrow afternoon when I get up, cant ride it at home though so it will just be static testing. Now running short on time as our last 2013 round is at the weekend and the bodywork n mounts are still very broken and need fixing, we may be able to get out on practice day on friday for some testing at speed.

Work calls.... back later

[Weldangrind]

Brilliant box! It should certainly keep the electrical bits cool.

[Wild_Alaskan]

looks like a very interesting racing series!

[humanbeing]

Programmable http://item.taobao.com/item.htm?id=3289740994
It runs on DC just like those Suzuki , so u need another suitable coil like this http://www.sanxin.com.cn/Exhibit/exhview.asp?pid=62 (stock: http://www.sanxin.com.cn/Exhibit/exhview.asp?pid=55) + a reliable rec/reg that supplies DC power
---
#17 The "developer" of that product tells the truth on ***REAL*** racing "curves"
http://www.motoyes.net/bbs/forum.php?mod=viewthread&tid=504178&extra=&page=2

[Jibberwobble]

Brilliant box! It should certainly keep the electrical bits cool.

Thanks, it was only a quick knock up and would have put nice radius corners on it if I had time.

looks like a very interesting racing series!

Yes this is our first year at it, been racing the minibikes four a few years now and the sidecars have always looked interesting. After a year or two of wanting a go I finally got my s**t together and aquired this old girl, then promptly chopped it up to make it 'less bad'. We are having a ball, the racing is very close and the team work side of things is very rewarding.

Programmable http://item.taobao.com/item.htm?id=3289740994
It runs on DC just like those Suzuki , so u need another suitable coil like this http://www.sanxin.com.cn/Exhibit/exhview.asp?pid=62 (stock: http://www.sanxin.com.cn/Exhibit/exhview.asp?pid=55) + a reliable rec/reg that supplies DC power
---
#17 The "developer" of that product tells the truth on ***REAL*** racing "curves"
http://www.motoyes.net/bbs/forum.php?mod=viewthread&tid=504178&extra=&page=2

Thank you Humanbeing. I am however having considerable trouble understanding the translated version of these pages and how I would go about purchasing the required items. I will go investigate some more........


Ran the engine again with the power jet pipe disconnected and it's exactly the same as before. Didnt have time to try different jetting due to being up to my pits in sticky goo bodging up the bodywork for one last battering. New proper bodywork coming over the winter.

[Jibberwobble]

Some nicer CF parts made for minibikes, 2x huggers, chain guard and custonm bodywork.

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/IMAG0312.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/IMAG0312.jpg.html)

http://i88.photobucket.com/albums/k180/jibberwobble/Minimoto/DSCF8914.jpg (http://s88.photobucket.com/user/jibberwobble/media/Minimoto/DSCF8914.jpg.html)

[Jibberwobble]

Well after a nice long w/e in Wales we had two days of sun and one day of wind and rain on race day.

The long manifold was causing problems in that it was creating this back flow thing and belching out a huge cloud of vapour that was soaking my arm and cleaning/dissolving Chads visor when he was out for the right handers! first thing was to rule out jetting and the new lower altitude in relation to the tank so we ran it with the fuel turned off and let it empty the float bowl. Even when it was starting to pick up revs at tick over due to getting lean on an empty bowl it still pumped out the plume when the throttle was twisted.

I used the top half of the manifold which is similar in shape to the old blue silicone tube elbow that was on there before and remounted the carb in it's previous position. The belching cloud was gone and we no longer had a racing tricycle steam train. So I can only imagine that the large volume manifold was storing some higher pressure mixture which then backflowed after the intake valve shut and then back flowed out of the carb picking up a second dose of fuel as it passed the tube. Some research needed me thinks.

It was running nice after remounting the carb and quali was looming so we left it be after that. Qualified 3rd which is our best yet and knocked 0.6 sec off our previous best lap time at this circuit with a 58.6 second lap on a 3/4ish mile track.

First start went well... up to second then nearing the end of the race laying in 3rd we broke the chair wheel axle and spun off. Second start went well with a similar result but we were on the wrong tyres and dropped back to 4th at the finish. Last race, did not start, we suffered a split chair wheel tyre and only noticed it on the way to the holding area :(

The zonger is pulling well against the other more modern engines, think it's still the slowest out there but not by much. Our outfit is the heaviest at 110kgs too but we arent exactly total fatties so we end up in the middle somewhere when you look at combined weight.

Going to give her a little run at an indoor track this w/e and may try that other carb. We will then look at what the next step is with the motor for some winter modifications.

[Weldangrind]

...we arent exactly total fatties

Quote of the day! :lmao:

Interesting plume theory. It never occurred to me that the venturi effect would work in reverse.

[katoranger]

So the next performance improvement will be diets.

[Jibberwobble]

Quote of the day! :lmao:

Interesting plume theory. It never occurred to me that the venturi effect would work in reverse.

The backflow thing happens with two strokes sometimes, when the piston is on the down stroke and compressing the contents of the crank case some mixture escapes before the reeds shut (or the reeds could be damaged) and if it passes the tube at speed it pulls more fuel out then gets sucked back in to the carb mouth for the next indunction cycle and helps its self to more fuel. This really screws carburation. I think boost bottles help sort this out a bit but to be honest I'm not an expert.

The thing I dont understand is why it's happening on a four stroke other than my complete guess above. The carb has had moments of doing this before too even with the short manifold. Leaky inlet valve maybe?

Didnt get to run it this w/e, our track day got cancelled!

Right where's that chocolate pie??

[Weldangrind]

The thing I dont understand is why it's happening on a four stroke other than my complete guess above. The carb has had moments of doing this before too even with the short manifold. Leaky inlet valve maby?

I'm thinking that the reversion is caused by the cam lobe profile, although there's only one valve in the pushrod motor. In a performance four stroke application, it's common to have some valve overlap that helps to fill the cylinder at high rpm. At low rpm, the result is reversion.

Not sure of that can happen with only one valve that is shared between intake and exhaust, but it's fun to theorize about over a pint.

[Wild_Alaskan]

There is a one valve four stroke? Are you sure, i really cant see any way this would work without a reed cage type setup in the intake. My pushrod lifan motor had two valves, A high performance four stroke can have 4 or even 5 valves on a single cylinder. If the timing is wrong (to advanced) then it can spit and exhaust pulse out the intake at low rpms pushing some fresh mixture back with it.

[Weldangrind]

Sorry, I meant to say one cam lobe for two valves. Hopefully that will make more sense.

[Jibberwobble]

Hello there, been three months since I did any work on the sidecar, we've just been messing around on it since the season ended. Must get back on it soon or it will be another **** fight like last year.

Still got all these issues to solve but havent worked out a plan of attack yet. Chassis mods aside I feel a minor engine strip would be beneficial, really want to get the carb out the way so really should make sure everything is ok on the engine before doing more manifold and jetting experiments. Valve seating, cam condition/profile, heavier valve springs or what ever I can find on improving one of these motors.

Got another idea in the pipeline for a second outfit too.........

[Weldangrind]

I'd be shy about heavier valve springs, lest you should wipe out the cam lobe. Instead, try a fresh set of springs and use two shims instead on one. Stuff like that is pennies on Taobao.

[Jibberwobble]

Thank you that's just the sort of information I need

[Jibberwobble]

Programmable http://item.taobao.com/item.htm?id=3289740994
It runs on DC just like those Suzuki , so u need another suitable coil like this http://www.sanxin.com.cn/Exhibit/exhview.asp?pid=62 (stock: http://www.sanxin.com.cn/Exhibit/exhview.asp?pid=55) + a reliable rec/reg that supplies DC power
---
#17 The "developer" of that product tells the truth on ***REAL*** racing "curves"
http://www.motoyes.net/bbs/forum.php?mod=viewthread&tid=504178&extra=&page=2

OK so I'm now doing a rebuild on the outfit, changing almost everything and would like to see if we can make this engine go a bit faster too. I have now acquired the above CDI using tbtrends which was a refreshingly simple exercise in the end.

Humanbeing talks of DC coil and rec/reg

So I now need to get a DC coil which seems reasonably straight forward but what about the regulator, Arent these AC to DC units anyway? (please excuse my ignorance) :hmm:

Anything else I need to change??

[Weldangrind]

If you currently have a 67mm bore, you need this: http://item.taobao.com/item.htm?spm=a230r.1.14.94.MbZvd3&id=13243492906

:D

[Jibberwobble]

That would be nice Weld but I have a 200cc limit to stick to :cry: