HELP: Stripped screws and seized engine

M

Mheppert

New Member
So I just purchased a new motorized bike today and took it for a little spin. As I pulled up to a stop sign to talk to someone about it I killed the engine out of politeness. After the conversation I went to pedal away and start her back up. I pedaled away just fine but as soon as I engaged the clutch my back tire came screeching to a halt and the rear tire no longer moves, even with the clutch disengaged. I took the bike home to open up the clutch cover and see if something was jammed in it or something and the wonderful people at the factory had apparently over tightened the screws and then stripped them. And being the poor college student that I am I don't have a power drill to use screw extractors or to drill through the head. And when I say they stripped them, I mean that it is one smooth circle they left me with. None of the other screws are this stiff as I have already dismantled the motor to see if the problem could be solved elsewhere. Being a motor biking noobie I could be completely wrong in my diagnosis. But I need to fix this this as soon as possible as I am booked to take it on a trip in five days. Any and all help I would be so grateful for.
Thanks all,
Matt

ride on
drn2
 
I am not exactly sure what you are saying wrong. What engine is this? Clutch screws are stripped correct? Any idea on what is causing it to not move? Have you taken the head off to look for interference like a broken ring?
 
YesImLDS said:
I am not exactly sure what you are saying wrong. What engine is this? Clutch screws are stripped correct? Any idea on what is causing it to not move? Have you taken the head off to look for interference like a broken ring?
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It is just a china two stroke engine and the builder does not remember where he purchased it from. I have looked in the cylinder head and everything looks fine in there, It seems like the clutch may be stuck engaged possibly.
 
Has your clutch cable slipped? Have you tried moving the bar itself that the cable attaches to? You can manually move that in to disengage the clutch and it should be able to free wheel. If that doesn't do it then you could have something else going on.

Can you move the rear wheel at all and here the engine move around internally? Like building compression and releasing compression?
 
YesImLDS said:
Has your clutch cable slipped? Have you tried moving the bar itself that the cable attaches to? You can manually move that in to disengage the clutch and it should be able to free wheel. If that doesn't do it then you could have something else going on.

Can you move the rear wheel at all and here the engine move around internally? Like building compression and releasing compression?
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The clutch cable and lever both move, although it is a little difficult to move them. When I try to move the wheels they budge less than an inch, but the cylinder does move ever so slightly.
 
Slogger said:
The drive chain may be fouled up under the sprocket cover on the left side.
Does the chain seem real tight?
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yes it does. it had far too much slack in it to begin with as the builder didn't use a tensioner, but there is definitely less slack in it now
 
The thread I posted the link to is all about stripped screws and the various methods of removal. I should have mentioned that.
 
Mheppert said:
I have been trying to but it seems as if the screws have been stripped by the factory
:-||
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Inspect it visually with a flash light and see if there is any binding that could be possibly pulled out by hand. It'd be a pain, but it'd get you at least rolling again. Sounds like those screws will need taken out though at the very least. Might have to take it to someone who has the tools to do so.
 
Mheppert said:
yes it does. it had far too much slack in it to begin with as the builder didn't use a tensioner, but there is definitely less slack in it now
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Everyone that buys these engines and has to work on them needs one of these things.
It will tap any frozen screw loose without drama.

http://www.harborfreight.com/impact-screwdriver-set-with-case-37530.html

There are several ways to get even chewed up screws out, from drilling to grinding a slot in the head for a screwdriver.
 
Have you tried rolling the bike backwards? If the chain is bound up inside the clutch actuator cover sometimes rolling it backwards will free things up. If that is the problem then your chain is too loose and/or not aligned with the sprockets properly.

Tom
 
I'm going to agree with Tom on this one because all the symptoms you mentioned point to the chain being bound up under the clutch actuator cover, try rolling it backward and it should un stick. It might take a good jolt to un stick it tho.

For the stripped screw heads, if you can drill the heads off all 3 of them then slip the cover off, the screws should come right out by hand or a small set of vise grips, there's no reason to try and save these screws as they can be replaced with allen screws nice and cheap. Of course, if you can successfully un jam the chain without pulling that cover then you can replace the stripped screws at a later time.
 
yeah, pull REALLY hard on back wheel to get the chain back out of there - loose chain will do that all the time until one day it will break the back of your motor off
 
crassius said:
yeah, pull REALLY hard on back wheel to get the chain back out of there - loose chain will do that all the time until one day it will break the back of your motor off
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Yup... I've seen a few engines with the back part torn off because of this... A prime example of why the chain needs to be properly adjusted.
 
More likely any stripped screws were caused by your builder and not the factory. Highly suspect as evidenced by your statement he doesn't remember where he bought it from? IF you bought it from him new, wouldn't there be at least some minimal service/warranty? And who builds a bike without a tensioner? WTF man!
 
Whiteride said:
More likely any stripped screws were caused by your builder and not the factory. Highly suspect as evidenced by your statement he doesn't remember where he bought it from? IF you bought it from him new, wouldn't there be at least some minimal service/warranty? And who builds a bike without a tensioner? WTF man!
Click to expand...
Who builds a bike without a tensioner? Many of us do. If the frame allows it and you have a method of maintaining drive chain tension, like horizontal drop outs or engine shimming, there is no reason to run a chain tensioner.

There are pages and pages of discussion here regarding the pros and cons of that infamous device, especially the kit supplied item. There have been some very innovative methods used to keep the chain tight as opposed to that poorly designed clamp on thing that has caused so many problems.


Tom
 
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