Hi guys, Bike has developed an issue. When shifting from 4th to 5th it feel like it’s not engaged 100% and causes a jerking motion and a loud (ish) noise that I can describe as a chain skipping sound. The gearbox generally feels tight and the above issue does not happen when I ride through all the gears up to 8/9k rpm. It only happens if I’m in a higher gear at about 50mph and then accelerate hard in 5th that the slipping sound and jerking occurs. If I drop to 3rd and go through the gears then it doesn’t happen. It appears to happen only under heavy load in 5/6th at lower speeds. Clutch bite is great, no slipping clutch at all so I’m pretty sure it’s not a clutch issue. It sounds like it’s trying to get into 5th gear for a second, slips and judders and then it’s smooth and pulls. Some guys in FB said could be the following: Clutch, dogs, clutch adjustment, oil, chain too tight, chain too loose,….I’m baffled! The chain is a bit tight (25mm free play) and the front and rear sprocket at all good, no worn teeth. Anyone had the same issue or can someone diagnose? Hope you can assist me. Great forum BTW.
If your chain has been over tight you could have damaged a rear wheel bearing. Pop it up on a stand and see if turning the wheel causes any unexpected noise. Might need to remove it for more detailed inspection, might as well check cush drives whilst our in there as well. The demands from your throttle causing less of a complaint when you’re asking for smaller changes. Whack the throttle open and that load, with a tight chain ? Worth checking anyway. It’s free and simple. Best of luck mate.
Better to have a slack chain than tight. What oil are you using and how many miles has the oil done? Any difference between hot and cold engine?
Thanks for the reply mate. I re-tensioned the chain to 40mm slack compared to the 20mm that was when I bought it. No strange noises when spinning the wheel. It can’t be the chain slipping as it was tight and all the sprockets are excellent condition. I was reading that someone had a similar issue and it was a plastic guard above the cam chain that had melted from the cam chain rubbing. The sound he heard was the cam chain slapping the casing. My sound can only be described as a slipping drive chain, plus I get the jerking motion too. I’m convinced it’s the chain….I’ll test in the morning and hope the chain adjustment has sorted it.
Where is your shifter when trying to engage the higher gears ? What I’m saying is are you able to actually lift your foot up accurately and not over stretching causing partial temporary engagement. Do you get false neutrals ? What does the chain guide sitting on the swing arm look like ? Is it worn through anywhere ? Try clutchless shifting into those problematic gears. Make sure axel blocks are orientated the same. Do you have any oil leaking from front sprocket area ?…..this jerking motion, when does it start and disappear if you do what ?….. just a few questions lol. Ignore the lot if the test ride goes well ! Best of luck mate.
Hi Wes, gear shifter is perfectly aligned to my foot, no stretching with no false neutrals. Chain guide looked good when I cleaned it yesterday, the chain runs freely on it. Chain looks new (ish). No oil leaking from the front sprocket. When I stick it in 4/5th it slips in low rpm, I either drop it a gear and accelerate hard and it’s fine then through all the gears. It’s a really odd one to diagnose mate. Just to reiterate. Scenario one: Accelerating from 1st to 6th past 7000 rpm (in every gear) is smooth, gears feel great, engine and gearbox sounds as it should. Scenario two: I’m in 3rd gear, for example braking to a stop but then carry on with the line of traffic (in third). Rpm are about at 4000 rpm, put into 4th (goes in no) then accelerate and then it slips, jerks etc. Drop back to 3rd (revs at higher range now) and then change to 4th and it’s OK. Could it be a faulty clutch? But please remember, my gears pull strong all the way, no Rev slipping. Just a chain sound.
I’m not sure, as I’ve only recently bought the bike four weeks ago, so not sure if the previous owner had the clutch apart. I’m tempted to crank open the case and have a look at the clutch.
From your description, It sounds like 4th gear has not engaged properly and the engagement dogs are slipping. This can happen if a selector fork is damaged. If this is the case , it means engine out to investigate.
What year is this bike? A slipping / crackling sound under high load at low RPM with loss of performance could be pre-ignition. My 2017 sounds bad pulling hard from low RPM so i try to avoid it. It loses power and makes a noise but i wouldn't say it jerks.
OK, so today isn’t a good day. New helmet arrived this morning and it’s too small. Then took my bike to a mechanic with years of experience on blades and who works at TT to find the fault. He took it for a test ride and confirmed fourth gear is buggered, dogs, teeth or gear fork. Gutted as the cost to repair is huge. My options are: 1 - Sell the bike as is with the fault. 2 - Get it fixed £1500+ 3 - Get my head stuck into my Haynes manual I mechanically minded, I was a mechanical engineer in the Royal Navy. If I decide to do this myself, do you think it’s a doable DIY job? Best place to purchase gears in the UK (2002 CBR954) TODAY WAS GOING SO WELL!
You've got the skills as long as you have the space, enthusiasm and time. Crack off all shafts that you need stuff removing from before removing the engine. ie clutch, sprocket, and primary/ flywheel if required.
Once the top and bottom crankcases are separated, you can access the gearbox components without having to remove the topend of the engine so it's not a complete engine strip down.
I’ve accepted the bike is gonna be off the road now and also that I’m going to do the job myself. I think it’ll be a long job but will be good to get stuck into it:
