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[magicmonkey]

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sounds like an intake valve isnt sealing properly, just thrash the shit out of it and it may come right

I'm pretty sure that the intake valves are seating fine, smoke only puffs out when they are open. I have a sneaky feeling that there's and exhaust valve stuck but I'm open to being wrong about that!

[bogan]

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I'm pretty sure that the intake valves are seating fine, smoke only puffs out when they are open. I have a sneaky feeling that there's and exhaust valve stuck but I'm open to being wrong about that!

if the compression is down on that one cylinder is seems likely it is valve not sealing properly, and valves dont stick (closed anyway) unless there is something seriously wrong, like a broken rocker arm. If smoke is puffing out the carb it seems likely that there is something wrong with the intake valve (should always be in vacuum there)

[magicmonkey]

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if the compression is down on that one cylinder is seems likely it is valve not sealing properly, and valves dont stick (closed anyway) unless there is something seriously wrong, like a broken rocker arm. If smoke is puffing out the carb it seems likely that there is something wrong with the intake valve (should always be in vacuum there)

Ok, that makes sense. Seeing as this is an overhead cam engine I'm assuming that this could be something like a wrong sized shim. There is clearance on the intake valves and I've turned the engine over by hand and watched them move, they seem to be functioning properly as far as I can tell from those basic tests ...

[bogan]

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Ok, that makes sense. Seeing as this is an overhead cam engine I'm assuming that this could be something like a wrong sized shim. There is clearance on the intake valves and I've turned the engine over by hand and watched them move, they seem to be functioning properly as far as I can tell from those basic tests ...

firstly, what are the compressions in each cylinder?
as its an engine that used to rune fine, i dont think itll be a shim or something similar, more likely when in storage the valve was open and aquired some corrosion, which is why i recomend thrashing it for a while to get rid of it, beats spending more money on it or selling it off as parts anyway!

[magicmonkey]

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firstly, what are the compressions in each cylinder?
as its an engine that used to rune fine, i dont think itll be a shim or something similar, more likely when in storage the valve was open and aquired some corrosion, which is why i recomend thrashing it for a while to get rid of it, beats spending more money on it or selling it off as parts anyway!

When you say 'thrash it for a while' how long are you talking abotu, a ride around the coast or 10 minutes in the garage reving with no load...

[bogan]

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When you say 'thrash it for a while' how long are you talking abotu, a ride around the coast or 10 minutes in the garage reving with no load...

it really depends on how bad the problem is, how low is the compression on that cylinder? how much smoke comes out, does it get worse at revs etc.....

[magicmonkey]

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it really depends on how bad the problem is, how low is the compression on that cylinder? how much smoke comes out, does it get worse at revs etc.....

Compression is about half of what it should be and the smoke can come out quite a lot. I get the impression that it's something which has been getting progressively worse as it sems to have been going on for a while but I've only noticed it recently, it does seems to get worse at revs as well ...

[bogan]

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Compression is about half of what it should be and the smoke can come out quite a lot. I get the impression that it's something which has been getting progressively worse as it sems to have been going on for a while but I've only noticed it recently, it does seems to get worse at revs as well ...

um, why does it seem to have been going on for a while if you've only noticed it recently?

basically, you have three options, try to kludge it, pay heaps to fix it, or sell it as parts.

[Bad Gixxer]

before you bin the whole project, and since you've come this far anyway, i suggest you get some Wynns Valve Lifter Fluid and try some of that in your tank. Take it for a good ride around the block a few times so yo'ure never too far from home, keep the rev's high but variable, and see if this clears the resin or verdigree on the valve stem and/or seat. If that doesn't fix it, then for the sake of a new gasket, just pull the head and see if it's a burnt out valve or whatever. if you find it'a a basket case and not worth repairing, then bin it or sell it off, or you might find that it's just a sticky valve that needs dismantling and cleaning properly. Look at it this way, it might be a cheap fix that makes all your other efforts worthwhile. Pulling a head off is no big deal, you may be even able to recondition the gasket and re-use it.

And while the head's off anyway, give it a valve grind and learn something else that will stand you in good stead for future mechanical adventures!! i remember my Old man making me grind cylinders by hand, wouldn't let me use a drill. He reckoned that was the only way to get it to a glass finish, right down to the final polish with Jeweller's Rouge. Then the overnight Kerosene test with the valves just sitting in the head loosely - he reckoned if the kero could get past the metal-to-metal seal without the springs in, then it wasn't good enough. Bit of a perfectionist my Old Man - they didn't call him two-tenths Ted for nothing! My point is, if you surrender now then you'll either be reluctant to start another job, or experience similar difficulties and find it TOO easy to pack it in. Don't let it get the better of you and make it a matter of principle, and bugger the cost (within reason).

[magicmonkey]

yup, finally managed to get the head off over the weekend, looks like th problem has been caused by a carbon build up on the valve seats rather than any physical damage to anything under there so I'm quite happy about that Now all I need is a spring compressor, then I can give everything a good clean and put it all back together. I've decided not to take the cylinders out though as there's no sign of anything wrong that far down in the engine and I don't really want to run the risk of causing myself more problems that I have to, especially considering that you can't buy new rings any more. Hopefully, once that lot has been done it'll be running well and I'll finally be able to put it back on the road.