Motorcycle Repair: steering problem, wheel hub, correct measurement

Question
Dear Christ,

Thanks for your reply. I found that the stem beering is worn out. After replacing, it is OK. Now I have an other problem :
I feel that my motorbike CM125 is not smooth when I drive at about 10-30 km/hour especially when I acelerate. I have replace the 4 crushdrive (at the back wheel hub) but it is not better (or just a little bit). If I drive over 40km/hour, it seems normal. Does that have something with the clutch or the cab? I use my bike almost in the street (busy streets) so it is quite tiring. I hope to hear from your explanation.


thanks and regards

Le thanh Hai


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Followup To
Question -
Dear Chris,

My motorbike CM125 Honda seem to pull to the left, just a little bit. But in a long run, it may make my left hand numb (the ellbow). I have check the alignment of the wheel and the forks. It's OK.

How can I settle this problem?

Thanks and best regards


Le Thanh Hai
Answer -
Hi Le.

How long have you had this particular bike?

It sounds like you could have one or more of a couple of things wrong here.

1)  Has the bike been in any accidents?  The frame could be bent if it has been in a bad accident or dropped at high speed.

2)  During the last chain adjustment, did you allign the rear wheel properly?  If the marks on the adjusters are not in exactly the same position, then the wheel will be mis-alligned and cause the bike to feel like it is pulling to one side or the other.

3)  Contrary to what you may believe, the forks may not be in proper allignment with the handlebars.  This is something that you cannot just "eyeball".  You need to check it with correct measurement technique.  For that you may need to go to a decent mechanic, but check everything else before you go that far.

4)  The steering head is loose.

5)  The steering head bearings are worn to the point of needing replacement.

As far as the numbness in the arm and hand, check the handlebar position.  It may need to be adjusted slightly.  It may be just a matter of proper arm position.

Let me know what you find.

Good luck and ride safe.
FALCON

Answer
Hi again, Le.

When you say that it is not smooth, do you mean smooth as in engine smooth or do you mean a "shake" or "shimmy" in the handling?

If it is engine smoothness, then it could be any number of things; I would have to know what type of engine roughness you are talking about.

If it is handling roughness, then it could be a few things.  

1)  The steering head is loose (the bolt not tightened to correct torque).

2)  The wheel bearings (usually front, but sometimes rear) are worn and need replacement.

3)  One or both of the tires are out of balance.

4)  One or both of the wheels is/are not tightened properly on the axle.

5)  The rear swingarm is loose.

6)  The swingarm bearings are worn.

Let me know what you have with it.

Good luck and ride safe.
FALCON