Help Jerky when I slow to very low rpm - ZXR250

asian english translation.

 

In the ZXR750 Haynes it say's to measure the chain tension on the side stand, thats all it has as per all modern bikes.
Most old bikes always had centre stands, probably a hangover from English & Italian bikes until the start of the superbikes hit the roads.The slack is there to stop the chain pulling on the engine when the suspension bottoms out, all due to the arc of the swing arm compared to the arc of the drive sprocket & wheel sprocket. It won't be much but their engineers will have worked out the slack to cope with it. Too tight is worse than too loose, within reason.You can load the bike up with rider & pillion & see what the chain tension does & adjust to suit & vise versa.

 

Risky, what are you doing up at 1:40 am.. you should be getting your beauty sleep.....

 

grasshopper, leaving one bed for another.

 

Good for you! lol

 

yep, and another late night.

 

Rose, I have a 2nd hand Cush drive here for a C model in excellent nick, $20 and its yours (plus shipping)

 

Sorry for the late reply, I measured the chain on side stand to have 7mm of slack on the tightest part and 14mm when on the paddock stand, it did seem a bit tight so I loosened it a tiny bit to 9mm on the side stand.
I checked out the crush drive and it seems in pretty good condition, can't see any damage or wear on it.
I still need to check out the spark plugs to see if its running lean, but I'm 90% sure this is the cause of the jerking.

I have also started having another issue with the bike its never ending...

Im pretty sure its just that the clutch is slipping but i will just check with you guys to confirm, or check if it could be anything else.
so i know the clutch is slipping because when I rev over about 9k rpm, the revs start to go up and power goes down as if i were pulling the clutch in a bit.

but also I'm not sure if this is a symptom of the clutch slipping or could be something else. When I have clutch pulled in, in 1st gear and am at a stop, i can accelerate and bike will start moving slowly with clutch pulled in.

this happens even after the engine has been thoughly warmed up.

I have also tried adjusting the clutch cable, which seemed to help a little bit.

either way i have ordered new friction plates and springs, i will be cracking it open tomorrow to have a look at whats going on.

will post up photos afterwards.

cheers,
Rsoe

 

Sounds like your clutch cable needs adjustment & lubrication. But hey new parts can't hurt

 

could just be the clutch cable but may aswell just do the clutch if you ordered it.

maybe watch some youtube videos on how to adjust the cable as you will need to when you replace it.

 

Have already tried adjusting the cable, didn't help with the slipping. i just lubed it up and now i doesn't go while I've got the clutch pulled in but is still slipping at about 9k rpm.


The clutch problem started off with it just being really, really difficult to shift gears, and kept going into false neutrals, so i pulled over and started fiddling with the shifter and clutch cable.

now it seems to be shifting perfectly fine, just slipping.

 

Could be a warped plate in the clutch taking up the clearance, it can happen when the clutch slips if it's gotten hot enough.
lay the steel plates on a piece of glass & see if theyre flat

 

Opened up the clutch, and all of the friction plates, steel plates and springs seem to be within spec, not warping or burn marks, but i did notice a couple of things that didn't seem right, Not sure if this is normal but the teeth on the friction plates were yellowy, and also the last friction plate to go in was not moved over into the separate slot.


Then when i opened it up i noticed that the nut in the middle was damaged.


as well as a little chip on one of the teeth.


would any of this contribute to the clutch slipping?

 

yeah i know, i couldn't get the damaged both off because it just spins the cog thingy around, so i just left it on, but after replacing the clutch and playing around the the clutch cable my bike is no longer slipping and running absolutely beautifully, so I'm not sure what caused the slipping in the first place, could have been that the friction plates and steel plates where in the order of .friction steel steel friction, etc. i changed it to friction steel friction, etc.

anyway I'm very happy now thanks to all who contributed

 

Good stuff

 

I concur, that's not mechanical.......more like butchery in my opinion. Pleased to hear your bike is running well