2005 KFX 50 will not move unless wheels are lifted off the ground

[New2TriZ]

Just like the title states, it starts right up, idles and revs just fine it seems but the tires will only move if you lift them off the ground. It will slightly move under its own power with no rider, but even the 50 lb boy on it and it wont move. I pulled the intake restrictor, dropped the exhaust (could not find restrictor in exhaust). Cleaned it all up and put it back together. Seems to be having the same issue. I am beginning to think it is the clutch but is there any way to be sure? Is there a test or adjustment I can do to try and eliminate the clutch as my problem? Also another friend of mine who is an oldtimer motorcycle mechanic mentioned the left hand safety start switch? Said when they are failing they work like a rev limiter except way down low. Is there a way to test this switch? Unplug it and use a jumper wire to see if that is my problem? I am at a loss here fellas and would appreciate any help or insight you can give me. Thank you in advance.

[chris p.]

sounds like the drive belt is shot.pull the side cover and check it out.

[LT80]

I agree, get into the clutchs and see what's going on.

[New2TriZ]

Ok thanks for the tip. So drain the oil and remove engine cover, inspect the drive belt? I have been through all the parts diagrams and have never seen a drive belt for this model. Also any ideas how to check out the clutch? What am looking for to show evidence its not working properly?

[LT80]

No.Don't drain anything.
I see this is a different design then I thought.
This is a centrifical type clutch (not a CVT/belt).
When throttle is applied, shoes fly out and contact the drive hub and turns shafts then the sprocket/chain.
You will need to check out the shoe assembly and related parts to see what's going on.

[New2TriZ]

No.Don't drain anything.
I see this is a different design then I thought.
This is a centrifical type clutch (not a CVT/belt).
When throttle is applied, shoes fly out and contact the drive hub and turns shafts then the sprocket/chain.
You will need to check out the shoe assembly and related parts to see what's going on.

OK so i drained the oil and pulled the clutch cover. Clutch seems to be in pretty good shape. Both grooves are still visible on both shoes and the hub measures 3.422" (max ID is 3.44"). The hub is slightly blued from heat but all in all not too bad of shape. Cant see why this would be the problem? I am starting to think it must be in the carb circuit? I have pulled the intake and the exhaust so there are no restrictors or blockage in either? What about air filter material debris entering the cylinder? I have found no trace of the old element making it in their but allot of material was missing. Again it starts and idles perfect just kinda of falls flat at the mid/top (bogs almost like large air leak). It is not so resistant to the rev if you lift the tires off the ground, but stills seems to bog slightly. Gonna pull the carb and do a full rebuild (instead of cleaning) and replace the intake/exhaust gaskets. I am hoping it is something silly, but starting to run out of ideas.

[LT80]

Ok, i know it starts and all but did you do a compression test yet?

[corbinsdad67]

sounds like it burnt a ring I would check compression like lt 80 suggested an make sure the nuts on head are torqued mine came loose after I rebuilt it an torqued to 12lbs

[New2TriZ]

OK so you guys were right I'm getting 60 psi at best. Cylinder and piston look good gonna try quick hone and new rings this weekend and report back. What is my ideal psi?

[LT80]

That isn't goin g to work.
Why would you do all that labor and not do it right.
Get a new piston (.5mm bigger) and have the cylinder bored to the piston and have it be good for a few years. :)
100-120 comp.