Exh vale seizure

Information relating to Matchless and AJS Models built prior to 1939
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1608
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Exh vale seizure

Post by 1608 »

Hi, need a bit of advice for my Brother who has had some issues with his 1934 Triumph 2/1 250 OHV. Now I know its not AMC but have some pity please. What would you recommend for lubricating valve stems Grease or oil, there are grease nipples fitted. If grease, then what grade. And, what sort of EXH valve to stem tolerance/ measurement in thou would be normal for this period of engine. You've probably guessed that the EXH valve has seized twice with consequences.
Thanks in advance
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paul knapp
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Re: Exh vale seizure

Post by paul knapp »

I use colloidal graphite oil on all my valve guides. Oil or grease will burn off leaving a residue but the graphite will stay locked in the pores of the cast iron keeping things lubricated. You can make your own, using microfine graphite mixed into the nipple lube oil or grease for ease of application.
The guide may be gummed up now causing the seizures, and should be scraped out. Without referring to 'the book', I would think a minimum running clearance of .005" should be sufficient for those old bangers.

Paul
___“As a hobby for the technically minded, motorcycling provides great scope.”

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Don't worry about the world coming to an end today. It's already tomorrow in Australia!


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Re: Exh vale seizure

Post by 1608 »

Thanks Paul, I think .005 sounds about right. And the colloidal graphite sounds impressive too. I shall pass that on.
thanks again
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Rob Harknett
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Re: Exh vale seizure

Post by Rob Harknett »

The old bikes are not too fussy, if the engine had not been used for years the valves were probably well coated and burnt, probably never got greased much either. . A good clean should do the job, and like the old days they will keep on going with whatever grease may be in the gun.
Of course theres better stuff about now. I pump grease in mine till I see it coming out, mucky but keeps the springs rust free. That smell of hot grease is how an old bike should smell, Runs a bit quieter after a greasing, but not for long. Most noise is due to rocker nuts a bit loose causing end play.
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Re: Exh vale seizure

Post by 1608 »

Paul, just to clarify something. Is the C/Graphite used on a regular bassis ie. every so and so mileage or just when building the engine and first running. I believe on these older machines you need to lube the valves every 50 miles or there abouts.
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Re: Exh vale seizure

Post by 1608 »

Thanks Rob, I think the main problem has been too small a tolerances on the re-build. He is new to pre-war stuff.
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paul knapp
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Re: Exh vale seizure

Post by paul knapp »

John, I use the colloidal graphite (Dixons) only during the valve assembly. I don't have any exposed rocker bikes, though I believe it would be an advantage to use it on any grease nipples there are around the valves. As said above, the grease soon disappears, but would leave any graphite behind adhering to the porous cast iron guides.
My owners manual for my ARIEL calls for graphite to be added to the engine oil at each change so someone back in those days recognised it's use as an advantage for the old ba......errr, bikes! :lol:
___“As a hobby for the technically minded, motorcycling provides great scope.”

J.B.Nicholson

Don't worry about the world coming to an end today. It's already tomorrow in Australia!


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