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.produKt
21st August 2010, 11:43
Okay, this one's got me stumped and i can't afford any workshop time, so here goes.

There appears to be a quickly developing issue with the gearbox/driveline.
At slow speeds or static speeds ie not accelerating (say around 20-30km's in a carpark or whatnot) the bike begins to hop and lurch and the only way to stop this/ smooth it out is to re-ride the clutch out. But then it happens again sometimes and sometimes not at all.

During the hoping/lurching the bike is giving me some nasty messages. Something doesn't feel right at all but i can't put my finger on it.

The chain is a tad loose but still inside threshold (20-30mm play/movement?), and even when it was in proper adjustment it was still doing this.

Can anyone point me in the right direction? Preferably to solve the problem myself :P

(Info:)
1992 CBR250RR(N) (MC22)
39,400 Km
Clean oil



Just noticed a wheel weight has possibly fallen off or was removed in the last balance...

bogan
21st August 2010, 11:46
cush drive

to verify check if the sprocket (rear) will move around a little bit while the wheel (rear) does not

.produKt
21st August 2010, 11:52
And no, the rear sprocket is thankfully still attached to the rear wheel firmly and does not move.

hayd3n
21st August 2010, 12:10
dirty air filter?
dirty plugs?
to much oil in engine?

bogan
21st August 2010, 13:01
as hayd3n says, may not be the driveline, though riding it you would probably be able to tell the diff. Could also be the anti chatter springs on the back of the clutch. Procedure to check is similar to cush drive, take of cover, rotate basket while holding the gear firmly (engine will do this for you), you shouldn't be able to get any movement out of it.

EDIT: oil will piss out everywhere if you take the clutch cover off without first lying the biker over or draining the oil...

.produKt
21st August 2010, 13:53
If you take the clutch cover off, would you have to then replace the clutch cover seal/gasket?

Will try adjusting the chain later today if it warms up =\

bogan
21st August 2010, 14:36
depends, if it rips when it comes off yes, if not you're all good

bogan
21st August 2010, 14:37
also, you can probly check gearbox/clutch slop by taking front sprocket cover off and rotating the sprocket by hand in different gears, will take more thinking but give similar answers probably.

Phreak
22nd August 2010, 02:13
Check out this website...

http://cbr250.com/forum/forum-4.html

I have found that a lot of guys on the dedicated CBR250 forums have a LOT of knowledge in dealing with our specific bike...

Good luck!

The Pastor
23rd August 2010, 09:48
any tight spots on the chain?

.produKt
22nd September 2010, 18:29
Nah no tight spots on chain but there appears to be a seized link, one that isn't in line with the others.

Also, i'm not sure it's a gearbox issue anymore, when it's lurching away the engine speed doesn't change

glegge
22nd September 2010, 21:10
just a crazy off the wall idea that will cost nothing, may show something up, or not - no loss either way.
someone may be able to follow along side when it's happening, perhaps observe something in the drive line.. chain/cush /whatever...

will probably turn up nothing, but may show up something obvious as well.

engine mounts tight?

.produKt
22nd September 2010, 21:56
just a crazy off the wall idea that will cost nothing, may show something up, or not - no loss either way.
someone may be able to follow along side when it's happening, perhaps observe something in the drive line.. chain/cush /whatever...

will probably turn up nothing, but may show up something obvious as well.

engine mounts tight?

I know the rear cush drive is perfectly fine, in fact it looks brilliant. none of the rubber is faded nor cracked/perished in anyway :niceone:

I have NFI about the engine mounts. My mechanical aptitude isn't the best.

Bike is going to Casbolts Honda after insurance approvals due to an incident last weekend so i'll get em to look at it then.

A warped clutch is another potential also

kevinthecarp
28th September 2010, 21:43
Sounds stupid - is the chain correctly adjusted. I had a 400 and the adjustment was critical to stop this behaviour. If this is the case, it will disappear with throttle and you may notice one 'lurch' when you shut throttle at any speed.

ducatilover
28th September 2010, 21:55
Easiest to check all the driveline first, then air filter, plugs, coil resistances etc. Air leaks?