Clutch Stuck - No Neutral

McMoo · Mar 2, 2014

First Post! Always wanted a motorized bike and just got a free motor but need clutch help

Just received a 50cc 2stroke engine and parts from a friend, mounted on frame and started with a drill as it had been sitting for a few years. Motor sounds very good with very little vibration. Clutch on the other hand is proving to be difficult.

I removed everything on the sprocket side of the motor, looked into the shaft and there is a ball bearing but no pin to push on it. The previous rider bought the motor used and never had the clutch working. I sprayed some fluid down onto the bearing and gave it a few good taps to try and release it. I know they do not travel far but It will not move at all.

I have checked out some of the threads here for adjusting/checking and am guessing that something in the clutch shaft worn beyond spec?

Looking for suggestions for diagnosing and unsticking the bearing so I don't have to run and jump on it! Please and thank you!

GearNut · Mar 2, 2014

The clutch release will not work without the bucking bar in place.
Tapping or even whaling away on the poor little ball bearing with a hammer and punch will not release the clutch. That is not how they are designed to operate.
Here is a search I did for you regarding the bucking bar:
http://www.google.com/cse?cx=partne...Search#gsc.tab=0&gsc.q=bucking bar&gsc.page=1
Once you get that resolved, and you do in fact have the rest of the release parts (hand lever, cable, release cam and sprocket cover) the clutch should work fine after it is all adjusted properly.
Do not hesitate to ask more questions. There are many here willing to help.

McMoo · Mar 2, 2014

Thank you! Will fabricate bar tomorrow and order new clutch parts then retest. It seemed to me that that ball bearing should have some form of movement even if it just spins in place... Can the ball bearing be removed from the sprocket side for inspection/replacement? Or is the ball captive/in a tapered shaft that you can only pull out from right side of the motor?

GearNut said:
The clutch release will not work without the bucking bar in place.
Tapping or even whaling away on the poor little ball bearing with a hammer and punch will not release the clutch. That is not how they are designed to operate.
Here is a search I did for you regarding the bucking bar:
http://www.google.com/cse?cx=partne...Search#gsc.tab=0&gsc.q=bucking bar&gsc.page=1
Once you get that resolved, and you do in fact have the rest of the release parts (hand lever, cable, release cam and sprocket cover) the clutch should work fine after it is all adjusted properly.
Do not hesitate to ask more questions. There are many here willing to help.

Greg58 · Mar 2, 2014

The thread below has a lot of info that will help also.

http://motorbicycling.com/showthread.php?t=222

Greg58 · Mar 2, 2014

Below is what you should have.

http://motorbicycling.com/attachment.php?attachmentid=9593&d=1245293071

GearNut · Mar 2, 2014

The ball can be removed from the left side of the engine with a magnet. The hole through the shaft is not tapered.
You would be surprised at the amount of force that the clutch spring applies to the assembly. Hitting the ball and thusly the spring and clutch mandrel will only wiggle it slightly for a split second.
In order for the clutch to be released the bucking bar, bearing ball and mandrel must be moved inwards towards the clutch and held in place in order to hold the clutch in the released position. Bear in mind that it only moves about 1/8" or 3mm total, if even that much.

2door · Mar 2, 2014

You're getting solid advice from builders who know. Take it.
Also I might add that lubrication of those moving parts, cam inside the cover, the bucking bar and ball bearing is essential. Use a good quality bearing grease on them during assembly.

Tom

Will122391 · Mar 2, 2014

I fabbed my bucking bar out of an old smooth 8mm bolt. They have to be 28mm exactly if I remember correctly.

maniac57 · Mar 2, 2014

I like using the blank end of a drill bit. Much harder steel. Cut it to length with a grinder being sure to keep it cool by dunking in water every few seconds of cutting. This preserves the hardness of the steel and it will last forever.

2door · Mar 2, 2014

maniac57 said:
I like using the blank end of a drill bit. Much harder steel. Cut it to length with a grinder being sure to keep it cool by dunking in water every few seconds of cutting. This preserves the hardness of the steel and it will last forever.

Then round off and smooth the edges where it contacts the cam and polish it. It will reduce clutch lever pull a lot.

Tom

McMoo · Mar 4, 2014

Such a great source of information. I wanted to share a video of the motor running after years of sitting to show how much of a Frankenstein bike I am dealing with.
http://www.youtube.com/watch?v=KrfKHuTQqIs

The photo was the one I was going by, I saw and animated one that helped as I am more familiar with centrifugal clutch setups, though the lever setup seems handy for how cheap parts are. I ended up putting it back together and running the motor and some revs and it seems to have loosened up a lot and to hear how loud it is. Pulled out all the nasty grease I could as the last rider did not have the clutch setup and junk seems to have gotten in there.

If I installed a centrifugal clutch with pull start on the right side would it "bypass" the clutch lever setup?

My final idea for this bike is to have it setup so I can pull start with centrifugal clutch (and have it engage above the idle rpm when giving it gas), and have the clutch lever. My thinking is that the centrifugal clutch will engage on rev, and have the lever in case it fails, or I want to rev it and then dump the clutch for what ever reason.

It gets weirder!
While turning the back wheel to check alignment the chain likes to buck/catch when the master link heads around the back sprocket(It seems too big). I used a dremel with a cutoff blade to cut some links off as it was too long and cut it perfectly. All the other links seem to go around perfectly. The tension on the chain also changes when it travels around. Can post a video on the chain problem but any ideas?

Thanks Everyone!

GearNut · Mar 4, 2014

A centrifugal clutch will act like just like you think it will.
The hand clutch will still operate if you keep the hand lever and cable intact.
Revving the engine up and dumping the clutch is a quick way of damaging the woodruff keys that lock the gears and sprocket in place. It can also knock the engine sideways as it sits in the frame. The mounts will slip on the frame's tubing if given a strong enough shock.
As for the master link not following the rear sprocket teeth smoothly, How worn is the rear sprocket? Do the teeth have a hook shape/ profile to them?
Also, sometimes even a new or good sprocket needs the teeth tips smoothed/ rounded slightly to allow the chain link pins to travel across them smoothly.
Also, is the master link new? If not, could it's pins be worn enough to allow the mating links to be spaced farther apart than acceptable?
Could it be a poorly made master link?
How well is the rear sprocket aligned? Does it have any wobble or off center up and down movement relative to the wheel's centerline?
How aligned is the engine sprocket to the rear wheel sprocket? Chains can tolerate very little misalignment between the sprockets. They like to travel in a straight line.

McMoo · Mar 5, 2014

Not thinking of burn-outs for clutch, try to limit the amount of times I have to engage/disengage the clutch for stopping as I live up a small road that very narrow.

Brand new rear sprocket, chain, master link. Sprocket has a very slight taper on teeth to make chain move easier. Almost no movement up and down, with maybe a 1/8 inch side to side when spinning. Motor straight on frame and inline with rear sprocket. There was a video posted here awhile a go on the best way to align a rear sprocket. What technique is best to ensure proper alignment of motor and rear sprocket?

GearNut · Mar 5, 2014

1/8" side wobble is too much. Any movement up and down will cause the chain to have a tight/ loose issue as the distance between the sprockets changes with each wheel revolution.
There are many different techniques to aligning sprockets. I sight down the chain, similar to sighting down a rifle, and look for any side bowing of the chain. You can also observe how the sprocket teeth fit in between the chain's inner side plates. The teeth should ride centered. If they favor the inside (wheel side) of the chain the sprocket needs to be moved outwards. If they favor the outside of the chain the sprocket needs to be moved inwards.
The sprocket should have a dish to it. This is there to help with alignment. You can install it with the dished side facing in or out, use washers between the rag joint and sprocket to space the sprocket further out if necessary and have the dished in or out with or without spacing washers, whatever is necessary.
Be careful that the chain does not drag on the tire's sidewall or drag on the bicycle frame. Some bikes are easier than others in this regard.

How is the chain? Even a brand new chain can be bad. Take it off and hang it up from the ceiling. Does it have a sideways bow? My most recent kit chain was horribly bowed in 2 places. It drove me nuts trying to center/ align the sprockets until I checked the chain.

2door · Mar 5, 2014

Have a look at this diagram. Maybe it will help you with sprocket alignment.
The red line represents a straightedge. I use a piece of aluminum channel that came from an old window screen. It is about 2 foot long and easily spans the distance between the engine drive sprocket and the rear wheel driven sprocket.
It should be self explanatory but just ask if you have questions.

Tom

McMoo · Mar 6, 2014

Chain is perfectly straight though I am replacing master link as it seems weak. Ill pull off the back wheel and try to align them better. All of my parts shipped today and am super excited to put them on!
#1 Motor Mount [#2-10-GB-F2-22-MM]
#2 Rear Motor Mount [#RMNT-3509]
#3 Bucking Bar [#3-26-GB-F5-6]
#4 Camshaft [#3-27-GB-F5-4]
#5 Clutch Column Shank [#3-28-GB-F5-3]
#6 Clutch Pads - Set of 15 [#3-8-GB-F5-28]
#7 Centrifugal Clutch Kit (with Pull Start) [#Cen Clutch kt with p s]

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Clutch Stuck - No Neutral

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