My nephew's small Chinese atv with a Loncin 117cc engine will not move after starting up this spring. I am guessing the 1 speed auto clutch is totally slipping. It seems strange to me that it would fail so suddenly but the engine runs ok and it does not move! It barely tries to move when the engine is revved up. It is 4 years old but not driven that much by a small kid and I do not know how good it really ran last fall.
Is there any other reason the engine will not drive the wheels that is a common problem?
It looks like the clutch is on the right side and is bathed in engine oil. Oddly, the left side of the engine has an oil cap on top of what looks like a gear box but I think it is dry inside and the magneto is actually the only thing in there! I am guessing the clutch has lined discs inside actuated by weights centrifugally. It looks like you can remove the clutch cover and replace the discs while the engine is still on the atv.
Does anybody have any experience with this set up?

 

Welcome to the forum ccrider966!

Weird that it would quit working like that... could be its stuck and not releasing(from sitting all winter).. Yes the clutch is under the right side cover(when sitting on the atv).. You should be able to get the cover off with the engine still in the atv.. Id take a look and see...

 

Interesting that it might be stuck because at first it would not start and it tried to pull when I shot some gas into the carb. Then I overhauled the carb and when I put it back together, I got the throttle slide out of position and it really revved up but the brake was on and it did not seem to move. It did really over rev before I got it shut off. I then corrected the carb throttle slide and it ran fine but when the brake was released it would not move! I do not know how the clutch is designed but I bet somehow it is stuck due to the engine speed but then it should then be stuck in drive position! Does this give you any fodder for thought?
Also I still wonder about the left side of the engine where the gear box has 2 plugs that look like they are for oil but there is a weep hole in the bottom of the case there and I think it is dry inside with only the magneto there. Is that right?
I am beginning to understand more about it and even saw a video on youtube showing how to replace the clutch disks!

 

Does it ever pull the quad around? or always just slip and not move at all.. Could be sticky and not stuck.. thats only if it does engage at some high rpm.. Have you tried adjusting the auto clutch at all?

The plugs on the left side are to access the timing marks on the flywheel..

You tube is great... lots of tech videos on just about everything..

 

I think it did try to pull the quad when I first was trying to get it started by squirting gas into the carb and I had to set the brake then but all that happened way back there in the beginning of my working on it and I am not really certain! Now it does not respond when revving it up other than a very very slight tendency to move forward.and it did not do anything when the engine over revved while installing the carb throttle slide. I would have thought that over revving it would cause the engine to become bogged down with the brake holding it back! It just seemed to be disconnected even then! If the centrifugal weights were stuck due to high speed, you would think the clutch would be engaged fully!
I wonder if something has become broken like the connection to the crankshaft or the connection to the transmission drive shaft. I hear no noise though.
How do you adjust the clutch? Do you have to remove the cover and tighten something? Could the disk linings be scrubbed off? The video shows a special tool to tighten the clutch nut also.
As you can see, I am completely unfamiliar with this item but I do have lots of tools and have good mechanical skills. Your help is really appreciated and this forum has been a big help.

 

To adjust the clutch you need to remove the cover plate from the right side of the engine.. under neath is a nut/washer and a stud/bolt sticking out of the case... loosen the nut... screw the bolt/stud in finger tight... turn it out 1/2 turn and tighten the nut...

If that doesnt work Id pull the side cover off and look at the clutch..

 

I will try that. Do I need a special tool to loosen the nut? Also if I have the cover off to adjust the clutch isn't that the same cover I need to remove to inspect it?
I cannot work on it today we have wedding to go to in the city.

 

14mm wrench fits the nut I think... no special tools needed yet.. Some Chinese Honda copies are like my minitrail and the nut is on the outside of the case... Most have a small plate covering the nut... That plate is mounted to the side case...


Removing the small plate will get you to the adjustment nut...

Removing the side case will get you to the clutch...

 

You are right, I went out to the barn and looked and there is an adjusting nut exposed, and I did not recognize what it was! You really know these things and I am so glad you responded! I wish I had your phone number in case I get further into this thing but you might not want to send that and I understand.....thanks

 

If I cant help you thru the forum...ill pm you my cell ph number..

But you gotta know..Im real busy 90% of the time.. work for myself... have a machine shop.. and am raising my g/s... and taking him to work with me everyday.. he is 3..

Just started posting in here after being awol for about a year..