Strange vibrations (QingQi 200gy)

[corporal_clegg]

Just on the off chance someone here has had a similar problem.

Was driving home yesterday enjoying the beautiful weather on a pretty empty road (ie. I was going pretty fast) when suddenly my bike started doing an new kind of vibration. My passenger said she had noticed it to a lesser extent on the ride out. I didnt, I thought it started suddenly. Maybe it started in the back... I dunno.

Anyway this vibration has a lower frequency than the engine vibrations. Feels like you driving on the broken lines at the side of the road, or like a wheel is kinked or loose. So far I have taken it to three mechanics and they all tell me it's fine. They can't feel anything. They try all the basic shit and give up ie. lube chain, tighten wheels..." sorry can't help. When it finally does give in tho, and your bike is really f*cked, come back and we can help you"

Has anyone had this problem or know any real mechanics in Shanghai (I keep getting sent to the shop where I bought the bike but that lot are a right waste of overalls too).

[Kot]

You should check for the wheel balance, rear hub bearing, bend disc brake, sprocket and etc.
Rim, tire, inner tube, wheel spock, and all comes to balanceing. All these has to be check.

[corporal_clegg]

Cool thanks man. The mechanics I've been to could only check things I could also check. Now I know more than they do cheers. Next thing is actually doing it. Will take a look the day after tomorrow.

[euphonius]

Good call, Kot. Tires are slapped on motorcycles in China with no thought to balance, unlike with cars. Yet an imbalance on a bike will be far more noticeable, and problematic and possibly risky, than on a car.

Inside joke: Any chance there's a section of iron pipe inside the tire? Stranger things have happened...

cheers

[corporal_clegg]

the bike is new (one month old, but it doesnt look it) and has been dropped almost 10 times (once at speed) and with 3500km on the clock. I think that the bearings are the most likely thing. The wheels look good and the're not going to suddenly go off balance are they?

[Kot]

.
.
I always go to the shop when working on tire, and hve both F+R balance by the balance machine.
Spend time and a few buck will worth while, less shake and better handling on road.

You can do your own balance by follw below step from Service Manual of Honda NSR150SP....

[zhu]

probably want to check the cush drive on the rear sprocket, specially if the local "mechanics" have been adjusting the chain cos they usually adjust it too tight. not allowing for the large amount of travel on a dirt bike

shagged cush drive will give a low freq vibe and eventually shear the sproket bolts...

leaving you walking home

[corporal_clegg]

yea well thats what I'm afraid of. I'd be surprised if the mechanics have the tools to do the balancing and stuff (I was surprised to find an air-pressure gauge in the local car wash shop). I'll take it to the garage where I bought the bike tomorrow. MCM, google translate and both english and chinese service manuals, It's going to be epic.

[Pal]

has been dropped almost 10 times (once at speed)

RIDE SAFE! check steering head bearings and get a decent tire gauge from overseas. Ride safe, PAL

[MotoKai]

Inside joke: Any chance there's a section of iron pipe inside the tire? Stranger things have happened...

Which reminds me, I have a RR to do (thanks).

Clegg - All the off-road you were doing could have packed mud onto your wheel creating a balance issue.
Last I recall your bike hasn't had a bath in ages. Did you wash the mud off it yet?