I noticed a weird issue on my '09 yesterday since I was at a track that has a couple of straights, one of which is fairly long. As soon as I shift up in 4th gear, it jump all the way up to 16k rpm, just below the rev limiter. It's as if it's slipping in that gear, but only that gear. 2nd, 3rd, and 5th are fine (haven't tried 6th, since the straight isn't quite long enough for that with the 15/43 gearing I have on now). I did a quick test where I got on the main straight at a slower speed in 4th gear, probably came on at about 5K RPM only, and then pinned the throttle back. It accelerated like you'd normally expect all the way to about 12k-13k RPM, after which it instantly jumped up to 16k again. It's not hitting a false neutral, because with false neutrals you bounce off the rev limiter and can definitely feel the difference. This is just right below the rev limit and it sort of just holds itself there for awhile, and it still feels like it's pulling a bit when it does that. I've never encountered this before, and I'm pretty baffled by it ...any ideas on what might be the issue and what I should start looking at? To my knowledge it's a stock motor and transmission, but that's just going by what the previous owner told me.
A bit more background info....the bike's been doing that ever since I got it a few months ago, I just didn't notice it as much because the other 2 tracks I went to were shorter, where you barely have to get into 4th gear. I had changed the oil before this weekend and pulled the clutch to change the secondary spring in the STM slipper clutch I have. I guess the only thing that might be possible is if the primary spring in the clutch is simply not strong enough for the power of the engine. STM clutches apparently use 2 springs that look like big Belleville washers. The primary spring is what pushes pressure on the plates which is what's connecting the power from the engine to the wheel basically, and the secondary spring is what determines the amount of engine braking. I had just changed the secondary spring because I wanted more engine braking. That all went fine and the difference was noticeable (not as much as I would've thought but enough to notice). While I was in there I measured the plates and stack height and according to the manual they're within spec still (OEM plates). Now as far as the primary spring, they have certain spring rates based on engine output. I checked the part number on mine and it's the default one that is used for any 600cc bike. Basically if you order a brand new STM clutch and you say it's for a zx6r, that's the spring that will come with it. So the only thing I could thing of, if this really is a clutch issue, is if that spring was pretty much on the edge of what it can handle, and with the full exhaust and custom fuel map on the PCV that I have the engine has just slightly too much power for what that spring can handle. But that still doesn't explain why it doesn't slip in any of the other gears
You have a bent shift fork in you're transmission.....it happened on my 09 zx6....exact same symptoms. Your bike is slipping out of gear, eventually 4th gear will cease to exist.
Well shit. Is it an easy fix? Where do I get a replacement part (aside from a dealership...I'd rather leave that as a last resort)? You're the 2nd person who suggested that, but I thought if it's popping out of gear, you end up in a false neutral...which doesn't give you any pull. Mine's still accelerating or keeping the speed steady, and it doesn't bounce off the rev limiter.
What is happening is the trans is popping back to 3rd gear( thats why you get the rpm jump but still have drive)...right now, it is slipping back to 3rd when you hit the high torque load of the engine....eventually it will not hold 4th gear under any load and will pop back to 3rd right away.......it is still rideable if you just forgo 4th gear.......kawi's have a cassette style transmission, its not that hard to replace, and you dont have the crack the engine to do it. I would search the salvage part sites and ebay to find the part.
Ahhh that makes sense! Well that gives me a place to start at least. It's funny I got rid of one bike (my Ducati 1198) that has a common problem with bent shift forks which caused a lot of false neutrals, and ended up with one that does actually have that problem lol. I guess if I have to I can always get a brand new one from the dealer. If it's really just that shift fork, I can't imagine it being very expensive. So long as the gears or other parts of the transmission need to be replaced, I'll be happy.
Turns out there's nothing wrong with the transmission. It was just the clutch. I changed out the friction plates and put some new EBC plates in and that did the trick. I guess it's just that sensitive that even 0.5-1 mm off the stack height can cause it to slip.
I wouldn't be so sure that it's completely fixed. It could just be masking the underlying issue. You didn't say what kind of bike. But Kawi's are notorious for this issue. My 08 ZX6R just started doing this on Saturday. Keep an eye on it. Typically a slipping clutch will slip and you'll see an increase in RPM's. But falling out gear or not shifting is a different issue. The clutch being better and keeping a load on the gears may be helping, but it may be an issue you'll see again.
I'm pretty sure it's fixed, it feels fine. And it's a zx6r. Just mentioned "09" without realizing I didn't put the name there because I copied the whole post from the zx6r forum where I posted it. And yeah the problem was just slipping, and seeing an increase in RPM in the high rev range (above 12-13K it jumped up to redline). I didn't say anything about not shifting and jumping out of gear. It shifts just fine. I'll get a much better idea in about a week at Road America since that's a track where I can get up into 6th gear.
Right! Same here. I was suspecting a slipping clutch for a week or more, by comparing what my tach said at certain speeds; 55 and 70 MPH, and what the Gearing Commander indicated what they should be. I was consistently reading RPMs above what they should be. In my bike, first I did what I could do easy, I emptied out the Mobile 1 Synthetic, and put in Valvoline motorcycle oil. The clutch stopped slipping and I'm getting tach readings where they should be.
One other thing to check, is the free play on your clutch lever. For the love of God, people, can we get a little free play in the lever? I've walked up to countless bikes that they say their clutch is slipping and the lever is tighter than a drum up against the perch.
Mine was like that when I bought it, and I suspect the reason for the plates wearing out so quickly (only 3100 miles) was because of that. Even after I loosened it a bit, I was still getting the slipping issue mentioned above in this post, just not quite as bad. But now I got new friction plates in and haven't had an issue all the way up to 6th gear.