mx 100 engine questions

[Daltonboys09]

ok the title says it all. we got it running today but the the idle / off idle is irratic. (he raised it up and removed most of the rear fender) :wink:
So on to my questions:
#1 are these bucket and shim valves?
#2 ya think that racing idle was hurting the engine?
#3 any body got any tips on this thing?
I ride an old seca (yamaha XJ) so Im used to checking valve clearences and endless carb tuning on it but Im not up to speed on this bike, I managed to clean the carb but Im not so sure about the smaller jet as to wether it really got cleared good.
any help is much appreciated.
oh one more question,
#4 are the yamaha pw 80 parts compatible really?

[Weldangrind]

If it's the bike I'm visualizing, then yes, PW80 body parts are probably a close match.

An erratic idle is usually a vacuum leak, so I'd start there. The only reason that high idle would harm the bike is if it sat long enough to overheat.

Not a chance are the valves the shim type. They'll be adjustable, with a stud and jam nut. Really easy.

Sometimes the only way to have a clean slow jet is to buy a new one. They're really small, and I've yet to find anything that I can clean them with, aside from compressed air and aerosol carb cleaner.

[katoranger]

http://craigupload.com/uploads/08_22_2011/img_20110822_03.18.58.5093470.jpg


The body looks PW80 and the engine looks honda clone. New carbs are cheap. Make sure the slide is not 180 degrees off too. [/img]

[Daltonboys09]

yep the bike in the pic is indeed the bike, and its a 100? kinda hard to believe but it dont matter this is just a trainer bike. ok the vac leak I can handle.
is there a "how to" on valve adjustment and what are the specs? Im used to bucket/shim with an over head cam so I have no clue about this bike.
the part I need is the rear sprocket hub, we busted that one. the plastic Im not to worried right now, I guess I could just change the whole rear assembly tire, rim sprocket and all to something I can get parts for maybe?

[Weldangrind]

This isn't the same type of motor, but the procedure is the same: Valve Adjustment Tutorial (http://chinariders.net/modules.php?name=Forums&file=viewtopic&t=1655) Let us know if you have any questions that are specific to your bike after reading it.

It might be a 100cc. There should be a number stamped on the cylinder head, but even that doesn't tell the whole story. There is a number on a pad near the gearshift that we should be able to decode.

The Baja 49 Dirt Runner is virtually the same bike and was sold through Pep Boys. Try searching for it on eBay for rear wheel parts.

[Daltonboys09]

yamaha pw 80, baja 49 dirt runner? even caught something about honda? just looking up jianshe or mx100 is impossible. I am soo glad my 30 year old xj and my 27 year old kz isnt as hard to nail down a part for!
Ok, can you find replacement parts for these bikes? or am I gonna have to get jiggy and modify this thing and put any 32 tooth sprocket rear hub I find first on it, Im pretty sure the engine dont know who made the rear wheel, its a chain right?
how about we try this, has anyone succesfully found and replaced the rear piece of junk metal hub? I see about 100 posts all over the internet where the same poor part failed the same way. If I can use use a honda or yamaha part Id rather, cause this china stuff-- well.
so is there anyone who has actually done this succesfully?
Im about to break out the fab department and solve this once and for all!

[katoranger]

We spent alot of time trying to track down a match. If you can fab I would make a yamaha wheel fit. Probably just spaces and maybe an axle swap.

http://cgi.ebay.com/ebaymotors/Yamaha-PW80-PW80-Y-Zinger-rear-back-wheel-rim-tire-brake-hub-sprocket-axle-12-/370545642601?pt=Motorcycles_Parts_Accessories&hash=item56463dcc69

[Weldangrind]

I believe that your bike is a close copy of a Yamaha PW80 rolling chassis with a Honda clone horizontal engine, hence the Honda and Yamaha references. It was a very popular platform, and there were several brand names that were vitually identical.

There was also the Panterra dirt bike that would be a potential search name. In Canada, we also had Orion and MFC bikes that were again identical.

My son didn't break his rear wheel, so I didn't need to address that issue. I bet that the rear wheel that Kato linked would be very close. In terms of sprocket matches, we'd need some sprocket measurements from you.

[Daltonboys09]

thanks guys, yeah Im gonna do that. I'll just mod it over little at a time as it breaks or just buy another one and part this out if something breaks. If they can ride it a couple of months then I got my money out of it Its just a trainer before I put them on a bigger bike. So the street china rides-- what are they like? how do they ride and how durable are they? my Xj is 30 ( rebuilt mostly) but it's almost bullet proof. I was looking at a 500 something or other (chinese) looked pretty good and it was cheap. also this Lifan I was looking at, 250 I think was 500.00? dont know much about china bikes though whats the quirks?