Cutting back ?
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@dtlee Examine the oil pump settings, make sure they are correct.
It might be the right hand crank shaft seal has gone bad, seaping Gearbox oil into the combustion chamber. Which I'm afraid, is a engine out cases split jobby to fix, since access to it can only be got at from behind the main bearings.
Always Originate, Never Pirate!
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the power valve pipe needs to be air-leak free. If it looks old and dry or cracked, replace it..
My number plate is dripping with shitty old 2/ from the silencer. It’s just the way it is with 2/‘s. Even if you pre-mix your fuel & oil...
Wet plug could just as easily be to much fuel or the ignition breaking down. It also depends if the engine was up to temperature? Cold engine makes for wet plug, in my experience...
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@spookdog thanks for your advice. I moved the Reed switch out from the Rev counter a long time ago and it’s always been fine. The problems I’m having now are more recent. Will have a look into the ignition and carb jets and see how I get on cheers
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That’s an electronic rev limiter isn’t it? I think the 1997 onwards bikes have them? Y/N? Maybe that connectors the problem?
I have an 1988 onwards wiring loom/CDI. So I wasn’t sure what you meant
A little back history is really helpful. When (& if!) it last ran proper, any changes you’ve made, Bada bada, bing bing! You get the pic? Helps diagnose problematic changes...
Carb jets won’t be the problem, they don’t change from right to wrong. Air leaks will, as will crank seals. I doubt that it’s that though. Not if the bearings aren’t noisy...
Seriously, I’d check the rev limiter mod
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Is there a way to check if the ignition is breaking down? I’ve checked everything mentioned above and cleaned the carb out etc. But still the book it’s cutting back intermittently at about 8000rpm. Before I split the casing and check seals I want to make sure I’ve checked everything else.
It seems to run perfect for about 20mins riding the then seems to start and progressively gets worse. Could this be as it warms up the ignition is failing
TIA
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@dtlee as electronics warm up the resistance changes I'd hazard a guess with the problems your having you might have a faulty ignition coil as the coil warms up it might be out of spec this is easily checked with a multimeter via the Haynes manual, my bike cuts back at the same rpm never been able to remedy it- edit when I say ignition coil I mean the physical coil on the stator not the ht coil although that also can be an issue when it warms up
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@dtlee I had this recently on my DT when I replaced the perfectly working coil for a Chinese "Racing" coil. It worked fine for the first 100 miles then just refused to rev properly.
Getting a nice genuine coil seemed to have fixed it.
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@declan just another though, I should probably checked that everything is earthed properly and that’s it’s not just something stupid like that? Do you know where the earthing point are on the bike. I had a quick look but couldn’t see anything obvious?
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Is there an easy way to temporarily disable the oil pump? I just want to check if it’s not packing up? It all looks correct but my plug is still oily and the bikes still cutting back at around 6-7krpm. I’ve checked the power valve isn’t the problem by pinning it open, took it for a ride and was still having the same issue. I was thinking of trying to pre mix the fuel and disable to oil pump to work out of its this causing the problem.
I’m running out of ideas with it. Failing this I guess it’s the ignition breaking down.
( I have cleaned out the carb, fuel line and the tank also and now put back on the original exhaust )
Any ideas I’d be grateful
