Cam shaft arm in too far to engage clutch!!

T james

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Nov 6, 2017
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Hey guys. Noob to motorized bikes. But have learned a vast amount just to get it to run. I have an 80cc china girl. Stock everything with the exception of NGK B5HS spark plug. Does 24mph solid, but rare moments I top out at 27mph. Which I did with stock EVERYTHING, but at bone rattling rate. It stop running for awhile. I don't know why. But I got it running and she now tops out at 24mph no problem. But now it seems the cam shaft arm is barely pushing the push pin to engage clutch/plate. Unless its pushed so far in that it sits under the carb before clutch engages and still feels weak as if cam arm or bucking bar has wore down. But neither has. It use to start to engage when cam shaft arm aligned parallel with motor. Now it has to be pushed/pulled in so far it sits directly under the carburetor. Correction, clutch doesn't fully engage at all. Only enough that u can pedal on gear 1 to fire up engine. I've notice clutch assembly has no spring between the drive gear and plate that flower key holds in place! Please help...thanks in advance!!
 

crassius

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Sep 30, 2012
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that arm should be pointing almost straight back when hand lever is released - if not, then loosen flower nut until it is, then do the cable/clutch adjust
 

T james

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Nov 6, 2017
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Thought so. Keep having to adjust without it. Also I see stock jet runs too rich. Because I rode it with WOT (wide open throttle) for a few miles and spark plug was charcoal black. And I'm certain that c-clip is adjusted correctly to the current main jet (on a 4 notch needle its set to 1 notch before richest mixture). Because if I move notch to richest mixture it won't start. Then if I move to a notch before leanest mixture. It loses 1mph of top end which is 24mph (well past break in with this being my 6th fill up). Another reason I know I'm running rich is because I only get about 17 miles a fill up give or take. She eats gas lol! I tried 66-70 jet. The 70 I couldn't get bike started. The 66 my top speed was 22mph vice versa 24mph with stock main jet. Which size I don't know. So that's what is making it so hard to decide which direction to go far as size of main jet. Should I try low 70's 5mm jets or low 60's jets. I'm thinking low 60's because it performed damn near the same as stock jet. Minus the 2mph. But correct me if I'm wrong
 
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T james

Member
Nov 6, 2017
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Ok, so I took baffle off and all man. It went from 23mph tops with 36T sprocket. To 28mph with no problem smh (previous top end was 24-25mph with 44T with a lot more low end torque)....I'm just amazed at how truly restricting the stock muffler is! My next mods definitely a sbp expansion chamber muffler, boost bottle, and disc brakes. Because any faster than 30mph and breaking will be risky!
 

Bo305

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Dec 6, 2017
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that arm should be pointing almost straight back when hand lever is released - if not, then loosen flower nut until it is, then do the cable/clutch adjust
It sounds like this guys got a similar/opposite problem to me, my clutch arms range of motion stops when flush with the motor and moves away from the bike from 6 to 9 o'clock range of motion instead of 6 to 3, should loosening the flower nut sort that do u think?
 

Bo305

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Dec 6, 2017
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The clutch lever is splined, so you can unbolt it, hammer it off, and change the position.
I was thinking it might just be in the wrong position, so your saying its prettymuch as easy as undoing the top bolt on the clutch arm? I was thinking it might be like that I just didn't wanna break the clutch arm.
 

crassius

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Sep 30, 2012
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changing the arm position on the cam shaft can be bad - one wants the flat of the cam to be aligned with the flat of the end of the bucking bar with just a bit of free play between them

I always adjust flower nut to get this alignment before I start to adjust the clutch or the cable.
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
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changing the arm position on the cam shaft can be bad - one wants the flat of the cam to be aligned with the flat of the end of the bucking bar with just a bit of free play between them

I always adjust flower nut to get this alignment before I start to adjust the clutch or the cable.
Changing the arm position has nothing to do with the shaft.

The arm is pressed onto the splines of the shaft, held on with a nut, and can be removed and rotated without disturbing the position of the flat side of the shaft.

I've built bikes where no amount of flower nut adjustment would stop the arm from hitting the engine or the carb, and re-positioning the arm on the splines is a simple fix.

I also custom made all my race bike's clutch arms by cutting off the cable holder end, and tapping it to thread on a car carburetor linkage spherical bearing rod end, and bending the arm on a slight angle to give me an easy, one finger pull with no cable bind, which causes breakage.

If I can find one, I'll post a pic.

All of this means nothing if the OP is missing the spring, though.
 

Greg58

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May 1, 2011
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T James did you replace the missing cover bolt that you talked about in another thread? That missing bolt will cause the arm to travel more. You can find the missing spring on eBay or from one of the vendors on the forum.
 

Bo305

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Dec 6, 2017
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They can be a pain to remove, but they do come off.I haven't broken one, but try at your own risk.
Can I ask what's your method exactly for arm removal? just undo the bolt, remove the washer, grab the cable end and tap or strike where the horizontal meets the vertical with a hammer?
I checked my flower nut that's way too tight aswell but I still think that's just a seperate problem altogether but I think I've got that side sorted by reading up on bikeberry
 

crassius

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Sep 30, 2012
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take off acorn nut - put on a thin nut to protect threads - place arm across top of vice loosely and tap nut down with hammer till it gets loose

put a scratch or other mark at original position in case you need to go back to it
 

Bo305

New Member
Dec 6, 2017
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Fixed my clutch/clutch arm, didn't need to end up moving the arm, just under estimated the amount of force needed to push it in toward the engine, first thought applying too much force to put it in the right place would break something but it didn't. Flower nut was way too tight, managed to remove it with a flathead and a hammer after thinking I was ruining the flower nut w the flathead I tried a socket that didn't work so went back w the hammer n driver and got success.
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
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living the dream in southern california
On most of my bikes, I could push in the clutch lever on the engine, then turn the flower nut with my fingers. Or use spread-out needle nose pliers.

The set screw for the flower nut is the only part on my bikes I would use red loctite on.
 

Bo305

New Member
Dec 6, 2017
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You need that spring. If yours is missing, nothing will fix it.
If it's the spring behind the clutch plate once u remove the flower nut your referring to I don't think it is actually needed, Apparently there's the old and the new and the spring Is only in the new ones (came across the info in a video) but yeah I've got the older one like old mate here and I got my clutch working fine without the spring, like him I never had one in my clutch to begin with.