Is this normal?

GoldenMotor.com

Jonda500

Member
May 10, 2014
86
8
8
Canberra, Australia
My first motorbicycle is a $20 malvern star fitted with a 90cc OZBIKE engine kit, but this engine I just discovered seems to have a bent drive shaft on the clutch end When I turn the sprocket with the clutch pulled in and the clutch cover off, the large primary drive gear (that houses the clutch) wobbles quite noticeably. When I ride the bike with the engine off the clutch makes a loud scrape scrape scrape... noise (not from hitting the cover when the clutch is pulled in too far, I fixed that problem). When using the engine I experience extremely bad vibration if I allow the revs to get even moderately high (still able to turn the pedals to help in top gear, so not that high).
Is this abnormal, or just par for the course???
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Personally I can't offer much in the way of advice. I'm not familiar with your engine, 90cc OZBIKE. However, any gear drive should rotate true and wobble free. If the gears can't mesh smoothly you're going to have noise and premature wear.
I'd go back to whoever you bought the engine from and demand a replacement.

Tom
 

Jonda500

Member
May 10, 2014
86
8
8
Canberra, Australia
Thanks for your response Tom. I don't think I'm gonna get anywhere with trying to get a replacement or refund. From the same website (ozbicycleengines.com.au) I also ordered a jackshaft kit, I was most upset to find the freewheel thread had been pressed on to the crank crooked and the crank was also bent and the pedal hole was not straight! Being a newbe with nothing but the one website that I had come across and no other resorces I went ahead and ordered another jackshift kit (after realizing they were never going to give me a replacement for the dud one) - stupid me - the second kit they just never even bothered to send!! ArrrgRRR- had to just forget about it and move on...
Luckily I have found the sick bike parts site now and have had no further such problems and think SBP is a fantastic site.
The engine has good midrange now that it's broken in so I think when I put a jackshift kit in to enable me to lower the revs (and also coast rather than letting the wheel drag the motor round at high revs down hills) it will be quite useable for as long as it lasts. I can't see any abnormal wear on the primary drive gear teeth yet... Lucky there is quite a lot of backlash(free play) between the cogs!
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
I've often seen motors come out of the factory that have the clutch crooked on the shaft (and sometimes without the key even in there). Either pull the clutch off and reseat it, or if you're adventurous, just try putting a piece of wood on it & smacking it real hard with a big hammer.
 

Jonda500

Member
May 10, 2014
86
8
8
Canberra, Australia
Thanks heaps crassius you've pinpointed exactly where my issue is for me and how to quite easily have a go at improving it. I am very grateful dude! I really had no idea what to do! :) :)