I'm new to this but hoping someone might offer some help. My 86 350 4-wheeler will start, run and idle but will not reach high speeds. I can rev the motor up but once it is in gear it will not pick up speed (just keeps moving really slow). It will shift gears fine but I can't seem to get the engine to pick up speed while it is in gear running. If anyone has any advise or suggestions it would be greatly appreciated. I hate to scrap it out but don't know enough about it to get it running any better...
Thanks much.

 

welcome to the forums! when is the last time you cleaned your carb?

 

Thanks for the welcome. It hasn't been long at all since the carb was cleaned. The motor will rev up fine when in neutral but will not reach high rpm's when in gear. It's like there is something keeping it from revving up when it is in gear. It will run when in gear but very little power. But the motor will reach high RPM's when it is in neutral... I was riding it one day and then the next day it would barely pull itself. Thanks for replying.

 

Hmm..If the carb was just cleaned, maybe your compression is bad? Try running it with the air cleaner off, or with high octain gas.

 

I had the motor rebuilt during last winter. Only had about 20 hours on the motor before it lost power when in gear. It is so odd that I can rev the motor up to high RPM's when in neutral and not in gear. But I will try taking the breather off and higher octane gas to see how it works. Will report back what I find. Thanks for the suggestion.

 

I just thought of something... When the engine was rebuilt, the valves may not have been properly adjusted, and it may have burnt a valve, I have an arctic cat 500 that revs fine, idles fine, but in gear.. Without the air cleaner, wont run but 15 mph.. (Which sucks) without the aircleaner, the thing runs great! If it runs great without the breather, then thats mostlikely your problem.. Dont throw it away though!! You dont see any 1986 yamaha's that still run at all.. :P Did it loose power all at once? just like... your running down a road, in high gear, you let off the gas and the engine sucks really loud, then bogs down? and ever since, all power was lost?

 

I had used it the day before and it ran top end with no problem... The next day I started brought it out of the barn and it wouldn't pick up speed. It never gave an indication that anything was wrong. It started and idled just like normal... I didn't know if there was something electronic that would not let it speed up when in gear (I just don't know enough about it to know which way to go with it) I'm going to take the breather off tomorrow to see if that if it will run any better. Thanks for advice...