Hi everyone, I'm new to register here, but I've been reading through the posts a lot over the last few months. There's heaps of great info on here, it's a great source of help when u need it!!! I've had an MC21 SP for about 8 months now, but i've got a question and i would be EXTREMELY grateful if you guys (and girls) could help me out with it. And who knows - maybe others can learn from this problem too.
I've had some work done on my bike since i bought it - i bought it with a blown engine, so I had the engine replaced with a second hand bottom end, and pretty much all new top-end. It rides beautifully (didn't expect it to be so good!!! NSRs absolutely rule!), but the second hand engine that's in there has always leaked oil from the seal around the front sprocket shaft. I've had 2 mechanics look at it, but i don't think they're really familiar with NSRs - they've replaced the seal several times, but almost straight away it's started leaking again! In some cases with oil literally exploding out.
The sprocket shaft itself seems undamaged, but no matter what, the seal still leaks. I'm starting to suspect an over-pressure in the transmission, forcing the oil out. Is this a possibility? Has anyone had this problem before? What could be causing it? Is there a breather hose for the transmission? Does the oil pump pressurise the transmission or is it for the 2T oil, or both? Could something with the pump be causing the problem?
There seems to be no 2T oil in the transmission, and the bike is completely happy except for the transmission oil wanting to get out through that seal.
Oh yeah - the engine that is in there is an MC21 R, with wet clutch.
I really hope someone here can help me solve this - because thinking about it has been driving me mad!
Hello, and wellcome, I have a 21r bottom end and i change the gear box/wet clutch for a sp/se box and dry clutch, Durning the change it was pointed out to me to watch this seal as you can NIC it and cuase damage when you replace the box, did you mechanics take the box out? as i cant see how they would change a seal with it in, On the inside there is a bearing and a seal with a spring in it, I would take the box out and change the bearing and seal at the same time someone here will give you some run out figures for the shaft to make sure its not worn or ndamaged!
Hi rc46, thanks for the reply. No they didn't take the box out, they've just taken the rubber seal/spring out from the outside and replaced it with a new one, the bearings behind the seal haven't been changed. I thought the seal SHOULD be pulled out and replaced from outside the box once the sprocket was removed. It would seem wierd to have to pull out the transmission simply to replace that seal... But you'd probably know better than me. And are you saying that damage to the SHAFT itself is the likely problem? Not over-pressure?
I would take the box out myself, just to be sure, if the seal can be replaced with box in place thats fine but at least with the box out you can make sure its sitting correctly, and there is no damage to cases and shaft! I dont know if there is any damage, but something isnt right, I didnt replace my seals, but i made sure they were seated correctly and the spring was sitting correctly, i also checked the bearing and shaft for damage. Mine dosent leak so something isnt right, so wip the box out and have a look, Its very very easy! the hardest bit about the whole job is getting the engine case back on, and craking the clutch nut!!! the box slides out after you take the 8 bolts out!.
Just had a thought!!! is there any play back n forth in the shaft? (back to front as you sit on the bike?
Not sure if there's any play back and forth, I don't think so though, because the mechanic has inspected the shaft and seems to think it's fine. I think you're definately right, I'll have to take the box out and make sure it's all ok. Thanks for the advice mate. And I suppose while I'm at it I should really look at putting the SP box from the old engine into this one (it's not doing much good sitting on my bedroom floor).
Will the SP gearbox/clutch drop straight into that R case? Or are there modifications I will need to make? How did u go doing yours?
Yup! if yuou have a complete bottom end from your old engine just swap everything accross, gearbox will slot straight in, engine case will slot in no prob!! when you slide the gearbox back in the is a spring wich pokes out!! near the bottom, just make sure you hold that out the way (i used a wide blade flat screwdriver) to slide the box home... One other thing take the gear selector switch out first before putting the box back (is on the sprokect side, 1 bolt and size of a small coin with wires goin into it) if you dont you may damage it. and youll find netural light dosent work!! if you need any help just pm me.
Off Topic: hey xstian, where abouts in Melbourne are you mate?
There is a few of us NSR riders in Melbourne and it would be cool if we could get together at some stage (when all our bikes are road worthy ).
There is a few of us in the Eastern/SE suburbs (I'm in Glen Waverley), and a couple in the North.
Cheers,
Jez _________________ Jerry Lai
NSR250 [MC21SP]
Hey Jez, Yeah would definately be cool to get us all together for a ride. I'm actually living more near Geelong at the moment, but it prob wouldn't be too much trouble to head around that side of the city (maybe on the ferry). Just gotta get my bike back on the road first. But yeah would be up for it for sure. Maybe PM me or i'll PM u when my bike is goin and we can organise something.
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