I have a couple of Yamoto 110cc ATV's, both have issues shifting.
They are very difficult to shift, particularly from 1-N, it seems to get worse when they warm up. I've adjusted the clutch but haven't had any luck.
Starting to think that they may need new clutchs.

Any thoughts?

 

Welcome to the forum mjdupre!

That is a common problem with that engine style...My Jetmoto 125 was hard to shift, but has gotten better with time. You could maybe try a good motorcycle engine oil if your using a normal 10wt-40 now..

 

I tried some high quality synthetic motorcycle oil (extra quart from my big toys) and still have trouble shifting, maybe even a bit more. I'm also feeling some slippage in first gear so I'm strarting to think it's time to replace the clutch plates.
I bought a couple of these used so I'm not sure what kind of punishment they've had.

I ordered a set of clutch plates, heavy duty springs and gasket from ZaksATVZone.com.
Hopefully get them in this week and see how that helps.

 

I replaced the clutch on one of the ATV's this weekend.
It definitely needed it as the plates were pretty burned.

This corrected the slippage problem in first gear but we still had problems with shifting, this seemed to get worse as it warms up. We adjusted the idle as it seemed to be idling a bit
on the fast side and this helped with the shifting. Being that this is a centrifugal clutch I
suppose this makes sense.

Having the spanner nut to remove the clutch is definitely required.
Even with it holding the clutch from spinning is no small task, a strap wrench comes in handy.
We ended up using an impact wrench to bump the nut loose while holding it with a strap.

The "clutch adjustment" on this unit is NOT exactly a clutch adjustment.
It actually is a shift lever adjustment as it only adjusts the tension on the spring in the
shift lever return assembly. It does not affect the clutch operation at all.

 

Hard shifting seems to be the norm on these...always wondered what caused it as the Honda engine they all copied shifts quite nicely...

Yes the adjustment on the cover is like setting the free play on a clutch lever..

 

Kind of wondered the same thing about the whole chinese ATV, pretty much cloned a Honda, still a bit baffled why it seems to have a few more problems than the Honda............

 

Mines actually shifting pretty smooth now after adjusting the idle.
Seems like the previous owner upped the idle quite a bit, probably because it doesn't like to idle when cold.

Speaking of cold idle......
I took the carb apart and cleaned it up good, hoping to fix the cold idle problem.
The larger jet (needle jet) cleaned up real nice however the smaller one (pilot jet) I wasn't able to see light through. I tried soaking it in carb cleaner overnight but no luck.
I'm thinking this could be my cold idle issue.

While it doesn't want to idle when cold, it sure starts up nicely now.