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2stroke expert advice desired

Discussion in 'Technical and Troubleshooting Torque' started by marky, Sep 28, 2011.

  1. Hey all, recently i blew up my bike, nsr150sp on the freewy which envolved a rear wheel lock at 140kph... Thankfully i didnt come off, but my top end was ****ed. So my japanese gf who was in japan at the time, brang me back a new cylynder and piston in her suitcase!!! Cool right!?

    Its back in... And it turns over, ive bled my oil pump as per service manual.. And it seems ok.. But, im ****ing scared to ride the ring in case it ceases again.... Wow do i know for sure its getting oil? Why did it cease last time? If it ceases again im truly ****ed.

    Any advice would be awesome
  2. Why did it seize?

    I expect there should be a way to test whether it's getting oil, have you got the service manual for it?

    Always cover the clutch ;)
  3. religiously check oil levels.
  4. Running a constant 140 km/h on the freeway would do it.

    As said, on a performance oriented stroker it is mandatory to keep at least a couple of fingers on the clutch lever.
  5. Or a big long off throttle roll from high revs. No fuel no lubrication.
    We did a demo race on 250's at Bathurst. Nearly all of us seized at the end of Conrod in practice. Of course this was pre chicane days on the strait too. So we were valve bouncing most of the way down the strait and off throttle and braking from about 250 out. Not a good mix for a 2 stroke.
    Keep a good eye on your plugs and headers. If the headers are going really blue they are getting pretty hot. Plug should be tan. Not white or grey... well unless you still have leaded or 100+
  6. Oh wreeeelly??

    Yep agree. It probably seized (and therefor ceased) as a result of leaning, rather than poor oil supply. After you figure out how to check the oil, get the carbie tuned (for wide open throttle at least).
  7. Ha ha good call. What do you call it when your reeds become flapped lol
  8. I think you need a new power band...
  9. Apart from the valve bouncing on a two-stroke, the rest is good advice!
  10. Yes those power bands become quite stretched after a while. :) OFF that's the noise they made. beeebbbbeeeeeebbbbbbbbeeeeebbbeeeee :)
  11. ..hmm so, get my carby checked. and dont ride it hard for long stretches..

    oil is always topped up, adn transmittion oil too, even though i cant see it in the litle window unless the bike is completely upright.

    whats with the clutch? you mean coast for a little bit? sorry im a bit lost, thanks for all the tips by the way guys its great. ;)
  12. marky, what type of oil do you use for your NSR? Only recently I use mineral based oil.
  13. experienced 2-stroke riders will have an ear out for lean-out. They will pull the clutch and kill the throttle at the first sign of trouble in order to minimize rebuild cost. You've lived it now, so next time you will know.
  14. Hard is fine on a twisty road with lots of on and off the throttle and a few gearchanges. Wide open for long periods without a break (ie freeway riding at near maximum speed) is what it won't like. We've got a contributor somewhere (boingk?) who killed his Aprilia RS125 in a similar manner.

    No. The idea is to keep a couple of fingers resting on the lever so that, as ibast notes, at the first sign of the engine tightening up you can pull the clutch in to minimise engine damage and avoid a rear wheel lock.
  15. Awesome.. Yeah i was too busy shitting my pants to hit the ckutch straight away haha,
  16. Scuze my ignorance but arn't these things oil injected ??? meant to run from 15 to 50 to 1
    Sorry but not sure.
    I would expect lean out on a premix. But not really on an injected.
  17. One last thing, does anyone have a nsr150 that could tell me how to set up my power valve? Its clearly not right, bike has no balls and sounds funny.. Service msnual is pretty lacklusyer about the setup.. At idle its sitting between hi and low right in the middle...
  18. It's a 150cc two-stroke. What do you expect? :LOL:

    Seriosly, though, I would expect the PV to be at one end or the other of its travel at idle, if it's anything like the old Yam YPVS system. Do you know if it's moving at all? Can you hear it cycling when you switch the ignition on? If not, there may be a problem with the actuation system rather than simply adjustment. Again, I'm basing this on YPVS experience yonks ago so Hondas may be different.

    With YPVS, if your servos carked it, or if the bike didn't have 'em because of the UK's mildly ridiculous learner laws, the trick was to set the PV manually at the max power end and live with the fact that the bike was gutless at the bottom end. Fixing it at the other end of its travel gave a relatively tractable bike that ran out of puff at ~100 km/h. Setting it in the middle gave a bike that was gutless at both bottom end and top end.
  19. Haha thanks mate, its still moving back and forward and everything, i had it in the middle, then set to high, as per service manual and its worse, so im gonna put it to L at idle and see what its like. With a top end changeover im expecting a slight pformance increase... 2 smoke happiness awaits!