1982 G1 rebuilt, ran once, now only backfires

[cgtech]

sounds like the sliding sheave is too worn out, allowing the weights to go too far and lock the clutch to the "full-in" position. still sounds like rig-jobs aren't going to work. parts availability for that clutch are "almost-zero" anyway (real yamaha parts, that is).

[JENNAKELLY5]

So after looking at http://www.buggiesgonewild.com/gas-y...g1-clutch.html i think I have some of my terminology wrong, but have basically done the same as suggested/performed here.

The only thing I can notice is that my cart doesn't have the cir-clip between the the two parts. Would this make any difference?

Would it be a good idea to sand/grind the fixed sheave to make sure it has no gunk or rust left on it and then re-grease? If i do this, is there a risk of overdoing it?

[cgtech]

Part #15, i dont think it would cause your problem (it applies to the "at-rest" condition). If you "sand" your sheaves, they will be able to get even closer to each other, offering the weights even better oppertunity to go past their normal range, might result in even worse of the same condition you are seeing now. If you are "hell-bent" on using this clutch as it is now, keep the rpms so low that the primary clutch never fully engages, so the weights cant ever get stuck. Most of the "commonly worn parts" arent available anymore. This is like beating a dead horse. Im out on this one.....

[JENNAKELLY5]

I don't really know what you're talking about cgtech but I meant sand the shaft part of #1, just to ensure it isn't getting stuck on there.

It would also be more useful to direct me towards "commonly worn parts" so that I could inspect them rather than just telling me the parts aren't available anymore.

I'm asking questions because I don't know the answers and I'm hoping that somebody on here can help me. If you don't know the answer to my questions then posting negative comments doesn't help.

[sho305]

This clutch has been out of production for a long time, in fact the one that replaced it (G9 clutch) is also out of production far as I know but can still get some parts for it. Anyway, the only trick I know is run a wider belt such as a 1 1/4" wide. This can help carts perform better than have worn clutches. Far as parts you can look at ebay and such you might get lucky, but don't expect much. Anything that moves in there will wear, the only thing that does not is if the fixed sheave is iron then they don't wear.

Belt wear limit on most yamaha is 1" wide, they get funky acting at that point and a lifted cart will not shift well it will bog.

Price a 780 comet Vegas carts has them, but you want a replacement not sure if they do them in 780s. You need a taper clutch with a pulley.

[JENNAKELLY5]

Pulled the clutch apart over the weekend for a closer inspection and solved the problem.
Looking at the engine side of the clutch, I noticed there were some pinch marks around the center lip where the weights were grabbing and locking on. Upon closer inspection I noticed that I was missing a large washer/spacer that the previous owner must have lost.
So I machined a rough washer out of some steel plate, glued it into position and reassembled, SUCCESS!

Cart now stops and starts smoothly and generally runs as it should. Thanks for all the info and tips along the way.

[pgiatis]

Rebuilt my G1 recently and had the same problem. Turns out I forgot to transplant the reed valve from the old head to the new one. Found this clue by removing the filter and seeing gas shooting out of the carburetor. Might check your old top end to see if you left in the reed valve.