I have got a 86 yammie 80 for the boys. When i got it i went through it fairly good, new plug, cleaned the air filter, changed the oil, cleaned the carb (adj. float two new gaskets, new o rings on intake, had the needle and seat pressure tested), and adj. the valves. Compresion test 150 psi. It has some stalling issues and no start issues but i think the new plug was no good or it fouled. Anyways the first plug was black as coal, so i went through the carb again and re assembled it and threw in another new plug. We went riding again tonight, no stalling and she starts with a touch of the switch, but the plug is black and sooty again. Any thoughts. Also i should mention that the jetting is believed to be stock, 80 main, 12.5 pilot. One thing that i question is the main does not seat on the shoulder of the jet to carb, but end of the jet to the tube. I am a avid sledder and have some experiance with jetting a sled for temps, and alt. but i am not sure if the little 4 banger needs this. By the way the yammie dealer is nof no help.[img]i/expressions/face-icon-small-confused.gif[/img]

 

could be that the carb. float needs to be adjusted (gas level in the carb. bowl too high). this can cause a rich condition. also is the choke turned off (opened) completely. the jetting is correct at 12.5 and 80. there is no gas leaking out of the carb. (overflow tube). this could indicate that the needle valve is worn and needs to be changed. I think that this would also make it run rich. [img]i/expressions/face-icon-small-smile.gif[/img]

 

I had a problem with mine running too rich on the little 87 80cc that I have. I ended up replacing the whole carb because I replaced, the needle, seat, jet, float, everything, only to end up with it running just the same and I had to replace the whole carb with one from a 2006 raptor 80cc and the problem was fixed.

 

The needle,seat was pressure tested and held aprox. 9 lbs, so that indicates that it is fine. The float level is adj. to factory specs of 21mm from bowl/carb mating surface to top of float when carb is inverted. No fuel comes out of the overflow either. And i had the choke apart and replaced the o-ring on the shaft and ground off the extra part of the screw that was sticking through the shaft, and it opens fine.Thanks for the ideas fellows. On a side note the needle is a 45$cdn part and you only get the needle, the seat is part of the carb. What a rip.