Same situation here , definitely clutch area not timing chain , noise quietens when stood upright probably because of the oil. At 1 minute when I release the clutch and load it up the noise goes away the same as your bikes. Not bad for a cold start eh
Clutches rattle and videos of engine noises never seem to work. I wouldn't be splitting engines unless it had a death rattle. When bearings fail they make horrible noises and leave lots of metal bits in the oil.
Have you guy seen this? https://www.2fiftycc.com/index.php?threads/1993-zzr-250.8957/page-4#post-113608
Yes. I think Linkin has changed all those bits & the ZXR clutch differs to the ZZR clutch...I'm pretty sure.
Yep, that's what mine does. Need to get to the bottom of this issue. I've never had it before on a ZXR engine. I agree with Maelstrom that it shouldn't be a pull it apart to fix job. @Linkin where is the positive neutral finder mechanism you mentioned? Is it in the gears near the first gear cog?
Phew, for a minute there I was thinking "how have I missed this?". Mine is an A engine. @TonyZXR is the rattle you have on an A or C engine?
But did he replace the basket with a brand new one? Seems you're trawling for an esoteric cause for the noise when it's likely the worn damper rubbers in the clutch basket assembly itself BTW in the thread I posted there were links to replacement rubbers on ebay so it's not an arduous task to do the repair as a first step before you contemplate splitting cases in search of something else
Yep... a couple of pages back but the complete clutch including the push rod and lever have been changed....
I think we are see that it is everyone's zxr. Mine rattles, too. There is an acceleration and deceleration pattern to the flat-plane inline-4 crankshaft. This will mean the gearbox also has an acceleration/deceleration pattern, where the springs and rubbers in the clutch might "bounce" without load, take up that effect when loaded. If you've ever drive a ute without a tray or just a light alloy tray, then you'll know about tye bouncing and topping out of the dampeners. Load the ute and it works smoothly. Also, the gearbox contains 6 sets of gears and 3 selectors, so there's plenty of parts there to rattle. If the rattle only goes under load, not by just pulling the clutch in, then it could be a timing chain wave - you might have seen this effect on a chainsaw or drive belt where it has S-shape on a straight or flaps in a pattern. But mostly, I wouldn't be too concerned, this rattle seems pretty standard. My 2c
Even the clutches with springs in the back will make a noise if the springs are loose. I'd be checking to see if there is any movement between the basket and gear first.
Okay. I will check all those suggested bits today and see what I find. I've had plenty of these bikes and this is the first one I've ever had rattle. Hopefully, it is something simple. @ruckusman I wasn't dismissing your suggestions or links, so sorry if it came across that way. Cheers
No that's OK - I walked into the discussion late, but as your potential diagnoses got more elaborate it made me remember my time with FZR carbs - the solution was simple but I kept overlooking it in search of more elaborate causes
Cheers. I do hope it's a simple fix too. I have to take this engine out of the frame anyway as it started to blow smoke the more we ran it. Murdo's diagnosis was valve oil seals as it seemed much worse on open throttle after a period of shut throttle. So, I have ordered new seals and I might as well have a good look at the rings and barrels while I have it out. I had previously done the valve clearances, but didn't touch the clutch.
I think now it's just how they are... at least for the 45HP motors Mine has had everything I can think of without splitting the motor done to address it, tuned and balanced to within an inch of its life. I'm not going to bother chasing it any further. It runs the smoothest it ever has and makes good power. I might do the manual chain tensioner when I do the clearances next, along with all the spark plug and valve cover seals. I've been riding around the last few days and the bike is performing brilliantly. I wish I could get to wring it out more often but it is not likely in 60-80km/h zones. Doing some revision and exams on engines and so on at TAFE today, two things jumped out at me that screamed 'my ZXR does that!' One was about aggressive cam profiles for top end / high rpm power and the effects at low and mid range RPM... those being a lumpy idle and a torque curve with a big dip in the middle. Well, the ZXR has a flat spot at around 7,000, makes peak torque at what? 14,000RPM with peak power at 16,000? That's exactly half of peak torque and where you would expect a dip... was watching a video on Yamaha EXUP's designed to counter-act that, as a variable-length exhaust pipe is not feasible. The EXUP and similar systems reflect the exhaust pulse back towards the exhaust valve, and when timed properly, prevent fresh mixture from exiting out the exhaust during overlap. Which incidently helps to smooth out the torque dip in the curve. Anyone who has ridden an FZR250 or a bike with EXUP will know that they make bulk torque from down low. So I believe it's just how it is with the design of the ZXR... perhaps they have those mythical race cams? People have always said in the past that the ZXR's were the most outright powerful of the i4 250's... I believe it. With all that said, I can't seem to stop that 'new bike itch' and looking at gumtree... I've held on to this bike longer than any other I've owned, so that should say something about it
So I pulled the ZXR valve timing numbers from the spec sheet and plugged them into this handy website which crunched the numbers and spat out a nice picture Don't ask me why their 'clockwise' rotation is backwards, makes my head spin. Here's the site if you want to play with it https://www.blocklayer.com/degree-wheel.aspx Intake Open - 46 deg BTDC Intake Close - 74 deg ABDC Exhaust Open - 63 deg BBDC Exhaust Close - 33 deg ATDC Overlap 79° Intake Duration 300° Intake Lobe Centre 104° ATDC Exhaust Duration 276° Exhaust Lobe Centre 105° BTDC Lobe Separation 104.5° (Cam°)
