We've got a runner

[JPG1911]

Finally got back over to the powersport shop today and got some jets. The shop I went to mainly sells quads, jet ski's, and Polaris side by sides. They said they don't normally stock jets and parts for the 30mm mikuni, but they allowed me to look through their whole box of spare parts. I spent the better part of an hour meticulously checking and sorting all the jets, lol. In the end, I couldn't find a 110 main and 25 slow as recommended. I ended up with a 105, 112.5, and 115 main, and a 30 slow for $12. I opted to start with the 115/30 combo with the pilot mixture screw 2 full turns out. Starting is markedly easier, and power has drastically increased. Top speed has fallen off by a few mph, but I'll happily trade that for the dramatic improvement in acceleration.

With the stock jetting, I had decent enough acceleration, and I managed to find a long enough straightaway to test my top speed. I managed to hit 62mph


The torque produced with the new jetting configuration is enough to slip the clutch a bit on hard shifts and nearly lift the front tire at WOT in 1st and 2nd, but I was only able to hit about 57mph on the top end. I suspect a sprocket change will have me in the mid 60's which is right where I want to be. I live off a 55mph road and I'd like to have a little room to escape if necessary. I will have to dive into some older threads and explore sprocket configurations. I remember reading quite a bit about it on here before, but can't seem to find those threads now.

I had previously replaced the broken front turn signals with LED units that worked great. I bought a set of 4, and today, I got around to pulling the luggage rack and rear end apart to replace the rear turn signals. The rears worked fine before, but I wanted to upgrade them to LED as well, when I hooked them up and tested them, I no longer have turn signals, but caution lights. Selecting either right or left with the switch makes all 4 of them blink now. I am certain that they are wired correctly, but I'm not sure if it has anything to do with the LEDs themelves, or if my switch just went bad.

That's about it for now, I still need to order my new headlight and mounting brackets, then I will have lots more wiring to clean up. After that, I plan to pick up the trail tech vapor and some softer tires, and I should have a great little commuter bike!

[SpudRider]

You need to replace your turn signal flasher with an LED flasher. You can probably find an LED flasher at your local auto parts store, or you can order one from SuperBrightLEDs.com.

https://www.superbrightleds.com/more...asher/787/842/

[ripcuda]

Nice progress! Your engine is an OHC 200, right?

Oh... and what app do you use for your speed tests?

Cheers!

[Weldangrind]

I bet if you throw the 112.5 in there with no other changes, you'll get your top speed back.

[JPG1911]

Thanks Spud, I was hoping it would be that simple, I'll pick one up.

Rip, yes its a Zongshen ZS169FML ohc hoindoid 200(223)
The app in the screenshot is Google's "My Tracks"

I'll give the 112.5 a try!

[humanbeing]

Originally Posted by ;184798

...itJPG1911s a Zongshen ZS169FML ohc hoindoid 200(223)...

It's NOT a 223 (15mm wrist pin) http://item.taobao.com/item.htm?id=35517374143
ZS169FML is different animal http://item.taobao.com/item.htm?id=36744024764

[JPG1911]

Ah! I stand corrected. Thanks for the info. I can't recall where I got that (mis)information, but I'm always thankful for correct information. That's one of the things I love most about this forum

[JPG1911]

I foolishly left the jets sitting on a shop towel that was within reach of my children, one of them must have picked it up, and after 3 days of searching, I have deemed the 112.5 jet to be lost to the depths of the backyard forever. Since I'll need to purchase a new one, do you think I should get another 112.5, or a 110 as was originally suggested, or both? The bike runs much better with the current 115/30 jetting than it did with the stock 100/2o setup, but there is still a slight bog at around 1/4 throttle, and it won't start without being fully choked unless the engine is fully warmed. If I shut it off and try to restart it after as little as 10 minutes, it has to be choked. If it is cold and choked, or hot and unchoked, it tends to start on the 2nd kick, but occasionally it is quite a workout to get it cranked. I have also been fiddling with the idle mixture screw, but I haven't been able to find it's happy place.

Also, I decided to try to rig my speedo cable from a XR250. It threads onto the speedo stem just fine, but I suppose the XR250 had a different securing mechanism at the hub than my bike requires.


This worked surprisingly well! I've put about 15 miles on the bike since attaching it, and it's very stable and solid. I don't recommend securing your speedo cable with zip ties, but if you're in a pinch, it does work.

Comparing the speedo to GPS, it appears to read about 4mph high, an indicated 45mph registers as 41mph with the GPS. The same holds true at an indicated 35mph, and at 55mph. I can live with that until I get a Trail Tech Vapor, it might even help to keep me from speeding

[ripcuda]

What does your spark plug look like... regarding rich/lean running?
Are you still 2 turns-out on the mixture screw? Adjust that to you highest idle speed is achieved... the reset idle to desired.
Bog/stumble or hesitation/hickup at 1/4 throttle?

If your plug is showing black/rich... you would probably benefit from that 112.5 main jet.

Cheers!

[JPG1911]

Plug looks pretty good, I would call it a good brown


At two full turns out, it was running rich. I had a slight amount of black smoke from the exhust and the bogging was worse. I ran the screw in a quarter turn, so I am now at 1.75 turns out. I plan to experiment a little more and maybe run the screw in another 1/8th of a turn or 1/4 turn to see how that does.

[Weldangrind]

The slow jet is responsible for the idle circuit, but you can crutch a too-small slow jet by backing the pilot mixture screw out a bit more. If you have the screw out more than two turns, the slow jet is too small. The pilot mixture screw is actually responsible for the transition from the slow jet to the main jet.

I'd buy an assorted jet kit if possible, so you have a 110 and a 112.5.

[Weldangrind]

BTW, the main jet will have no effect on the choke position while starting. Only the slow jet (and pilot mixture screw) will.

[JPG1911]

Excellent information! I will pick up the jets this week if I can find them in town. Do you think going to a 0.035 or 0.040 slow jet will allow it to start easier without being choked? Or is that too much? Going from 2 turns out to 1 3/4 turns out didn't have any noticeable impact on ease of starting, but it runs and idles much smoother.

[ripcuda]

I don't think you would want the idle speed so rich as to never need choke when cold starting. Ideally you want it so no choke is ever needed on a warm/hot restart... and only needed on a cold start for a short period till it can idle w/o it. Too much richer than that and it'll be boggy or feel lazy throttling around just off idle.

If your having to choke it after a 10min cool down after running... yeah, that sounds like a little more fuel in the pilot could help.

Adjust your mixture screw so you get the fastest idle speed with a warm idling engine. Then readjust the idle (not mixture) screw to desired idle again. If you lost count of turns on the mix screw... turn off engine, screw mix screw in while counting until seated (gently). Then back it back out the same number of turns you just counted. Somewhere between 1/2 and 2 turns out should be fine. < 1/2... too rich - downsize pilot jet. > 2... too lean - upsize pilot jet. If you change jets... gotta do it all again.

I think your plug looks good. That's a read after taking the bike for a spin, right (not just sitting there idling)? So it's more a mid-circuit to main jet read verses idle circuit. That said, I'd go with it... leaving it unchanged. Perhaps your lost few mph are because you're no longer too lean. Lean is mean... but not good for longevity.

Just my thoughts. I too am chasing jetting perfection on my PZ30 carb. It is a PITA. I'll be happy to get it dialed in.

Cheers!

[JPG1911]

Yes, that plug was pulled after a 5 mile ride. I'm no stranger to reading plugs, and I think it looks quite healthy. I agree with your thoughts on choking it when cold, thing is, it doesn't matter if it's cold or hot, I have to choke it, it starts and barely runs, I have to immediately unchoke it, then it runs fine.

Also, I cannot access the pilot screw with the carb mounted, I have to loosen it and rotate it in order to get a small bit in there. I saw where another member had heated a screwdriver and bent it to allow him to make adjustments with the carb still mounted, maybe I'll try that tonight.