Engine dies at high revs

[Fidge]

Too Lazy To Read - bike wouldn't idle, choke seems blocked, lost power around 8000rpm 50mph and often dies at high revs since then. I think it may be blocked valve and/or broken piston clips, what do you think?


The bike wouldn't idle when starting and the choke wouldn't work, on the way back from college doing 50 at around 8000rpm my bike just lost all power and stopped (luckily at a lay-by) it was a bit like someone had hit the kill switch or it had ran out of fuel.

A minute later I started it again, I revved it a few times and there was a bang and it stopped again (thought someone had jammed something in my exhaust and it just popped out). It then wouldn't start so I left it for a while. I then carefully rode it at bit further until I got to some less busy roads. I then rode into high revs and it cut out again and I had to wait a while to start again. I then rode it back a bit further around 50 and 40mph in low revs for around 6 miles and when I got off the main road I went into high revs but this time there was a really loud bang and it stopped, I have messed with the kill switch a few times in the past to make pops but this bang was 10x louder. I then waited a minute and carried on.

So whenever I go into high revs (in gear) the bike dies. Revving in neutral seems like i have to twist the throttle further to hit the red line and sounds rattly like a chainsaw and shakes from 8000rpm up.

I think the problem may be the RC (power) valve being blocked or broken piston clips. What do you guys think?

[pdg]

Whatever made you think it was a good idea to use the killswitch to create backfires?


Edit: seeing as I can't be bothered to try and find out another way, what bike?
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Any and all advice given should not be followed - if you have to ask it means you don't know so get a man in to do it for you.

[mentalboy]

Is this the same bike that you changed the carb on back in October? If so did you ever sort out the mixtures?

Sounds to me like it was originally a fuelling issue but I'd be checking the compression before I started any work (not much use to you unless you've been keeping tabs on the compression and know whether it's changed or unless it's significantly low for the model)
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Make mine a Corona.

[Fidge]

Yep, same bike, NSR 125 JC 20 model. It ran fine so I didn't change the mixture. I tried to check the compression a month a go but I only got really low readings for my bike, I'm supposed to get 10kg +-2 but I would only get 2kg. It was really hard to get the tester on and even then I don't think it was quite on properly.

I think it might be something related to to running at the wrong mixture .

[Fidge]

[pdg]

So you might well have buggered your RC valve then - well done

And if you've been running it since october on the wrong mixture, yes your extremely low compression reading may well have been caused by that....
____________________
Any and all advice given should not be followed - if you have to ask it means you don't know so get a man in to do it for you.

[mentalboy]

[Fidge]