The joys of bikes... Need a bike doctor. Stat!

[benbarlow321]

Here goes.
Bike: NSR 125 R-1

So yesterday my bike decided it would bog down about 30 seconds after I'd set off from home. I'd not given it the usual warm up, only 30 seconds or so. The revs just kept dropping until the engine cut out. I managed to get it started again another minute later, but it would only get up to 3k revs, and again cut out. Walked it home, threw a hissy fit and left it till today. Today, I managed to get it started again, had a ride round on it for 10 minutes and thought it had fixed its self - deceiving little machine. But again it bogged down.

Its *very* difficult to start and when it does, idle is very low, even on choke. Occasionally it'll climb to 8k revs with no input from me, but I'm far too scared to let it keep climbing, so just have to cut the engine.

I've recently had my cylinder replaced, but i think this is more of a carb issue. I have fuck all bike tools at my house, just the usual DIY ones. I can't even get the spark plug out yet. Plan to go buy a spark plug socket tomorrow. That's number 1 on the list. There's the possibility of blocked jets and a dirty carb too.

Just wanted to see what you guys thought was up with it. Any ideas? What should be my steps? I'm in the Blackpool area (St Anne's) should one of you kind souls wish to lend me your expertise Free beers for any takers Wow this has turned into quite an essay.

Thanks guys

[Pete.]

Sounds like you've wrecked the top-end.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[stirlinggaz]

hi,
definately try a new spark plug.
then think about buying a compression tester,(get the gunson or draper one, with the correct sized adaptor) as some of the symptoms your bike is showing, is indiciative of low compression,
cheers,
GAZ

[benbarlow321]

Ok, will get the spark plug swapped over tomorrow.

Is low compression characteristic of a knackered top end? Seen as a garage did my new cylinder for me, is this their fault for not fitting it properly, or is it just bad luck/my fault?

[stirlinggaz]

hi,
if you had a new cylinder fitted, im presuming you had a new piston + rings as well? & new small end bearing?
so its got a new top end.
did you run it in?
did they tell you to take it easy for a few hunderd miles? this is critical to to prevent a premature seizure (supposedly) & if you werent told this, you should have been!
stick a compression tester on it & tell us what it reads. (remember to hold the throttle wide open) take 3 or 4 readings & take an average.
also look out the number of the place that done the work.(you will need it)
Revs climbing of their own accord is usually either a stuck throttle cable, an air leak at the intake or f*cked main seals.
cheers,
GAZ