Barksavon
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| posted on 3/10/10 at 08:48 AM |
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worn valve guides ??????
Pinto head recently fitted with new valves , springs, valve seals, engine seems to be using a bit of oil and theres oil on the threads of the spark
plugs when i take them out, engines running ok on bike carbs plugs are a bit sooty too so probably a tad rich but want to sort out the oil issue, is
it likely to be worn valve guides ....???
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rusty nuts
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| posted on 3/10/10 at 09:15 AM |
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One symptom of worn guides is a lot of smoke when revving the engine after it has been idling for some time. IIRC Pinto guides were just holes in the
head rather than a proper guide? Any decent engine reconditioners should be able to fit guides and recut the seats to suit.
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MikeRJ
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| posted on 3/10/10 at 10:07 AM |
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Either worn guides or worn bores/piston rings. A dry/wet compression test will show up poor ring sealing (though if you have broken oil rings it
won't)
[Edited on 3/10/10 by MikeRJ]
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Barksavon
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| posted on 3/10/10 at 11:19 AM |
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there is some blue exhaust smoke and the engines been re bored with new pistons and rings, so i'm thinking it may well be valve guides. Ive done
a compression test and am getting about 175 - 180 psi on each cylinder, am i right in thinking a wet / dry compression test is doing it twice, once
having squirted some oil into the spark plug hole
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MikeRJ
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| posted on 3/10/10 at 12:02 PM |
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Yes, if the wet test is significantly higher it would indicate poor ring sealing.
Were the bores correctly honed after the rebore? It's very important this is done correctly to achieve a good seal and oil retention.
[Edited on 3/10/10 by MikeRJ]
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Barksavon
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| posted on 3/10/10 at 12:48 PM |
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Mike I'm not sure this was done, i didnt do it not sure about the machine shop although the bores did seem to have a decent cross hatch
appearance..... i have read - since i put things back together, about the running in process using thinner oil etc to avoid glazing in the bores,
i'll probably take the head off over the winter and have a good look.....
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Canada EH!
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| posted on 3/10/10 at 03:57 PM |
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How many miles since rebuild? How hard has it been driven, rings need some high power runs to seat properly, rich mixtures will wash the oil off
cylinder walls and accelerate ring wear.
Easy way to check for valve guide wear, coast down a large hill with the transmission in a low gear, punch the gas at the bottom of the hill and look
for blue exhuast smoke in the mirror.
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jacko
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| posted on 3/10/10 at 03:58 PM |
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What oil did you use to run it in
Not synthetic i hope
Jacko
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Barksavon
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| posted on 3/10/10 at 06:25 PM |
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about 750miles since rebuild, its not really been driven hard and i didnt use synthetic oil, i'll try the test for the worn valve guides next
time i take it out....thats assuming its ever gonna stop rainin!!!!
thanks
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