Valve sticking conundrum

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Valve sticking conundrum

Post by csx355 » Thu Feb 07, 2019 10:03 pm

Hi all - I've decided to start a new thread with this one as I think my original issue has been answered. Having re-built my ex competition B44 motor everything appeared to be fine apart from my concerns ref the oil pump.
The bike started fine and ran sweetly BUT the return oil supply was poor and I heard a nasty metallic squeal. Stopping the engine and stripping down the head revealed a stuck Exhaust valve as predicted by MightyMenace. Excellent - I love finding confirmation of an issue.

So new oil pump and internal oil valves and springs. New inlet and Exhaust valves as the old ones were home made items from the original owner. Rebuild and re-start. See you tube video here [youtube]https://youtu.be/OzDOz83svCw[/youtube]. The oil return is now super strong and much more like I was expecting.

The bike starts reasonably easy, given that it's just been rebuilt and I have not yet strobed the Electrex, but shortly after this I heard the metallic squeal again and stopped the motor to find that this time the inlet valve had stuck (briefly) giving me a massive tappet clearance.

I'm now pretty much at a loss. The valves were free and easy to move in their guides and lapped easily by hand. They would 'fall' through the guides under their own weight with assembly grease and oil. I don't get it. And to cap it all the bloody camera on my iPhone has decided to throw a wobbly giving everything a 'soft focus'. So I thought I would share that with you as well. The B44 is top right.
IMG_0007.jpg

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Re: Valve sticking conundrum

Post by minetymenace » Thu Feb 07, 2019 11:39 pm

Have you done the plasticine test to see the clearance between the piston and valves? Any witness marks on the top of the piston? A ding on the piston could bend the stems and make them stick...
There is no evidence to support the notion that life is serious.
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Re: Valve sticking conundrum

Post by csx355 » Fri Feb 08, 2019 8:54 am

I did with the original valves but I must admit not with these new ones. I checked the piston for signs of contact when I took the stuck exhaust valve out and there were none. I will whip the head off again next garage day and check things out. Everything is perfectly free to turn by hand.

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Re: Valve sticking conundrum

Post by minetymenace » Fri Feb 08, 2019 10:02 am

The only other thing I can think of, is the cam followers turning. There was a thread on this last year, and some people said they had experienced this, but on my (late) engine, this cannot happen, but if you have a mix or parts.....
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Re: Valve sticking conundrum

Post by csx355 » Fri Feb 08, 2019 12:43 pm

I did read that thread viewtopic.php?f=3&t=7726&hilit=push+rod+valve from Mike - I might pick his brains as well as there might be some commonality.

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Re: Valve sticking conundrum

Post by Canberra » Wed Feb 13, 2019 1:03 pm

The only time I had one of my valves stick was immediately after a rebuild when I used light grease on the valve stem. I figure it stopped the oil getting through on initial start up. I reassembled using engine oil and no problem.

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Re: Valve sticking conundrum

Post by csx355 » Wed Feb 13, 2019 2:54 pm

That's interesting - each time I rebuilt the motor I assembled it with this assembly grease http://shop.srmclassicbikes.com/product ... ube-sachet - ultra sticky - but it did dissolve in oil. I couldn't quite figure out the method of valve stem to guide lubrication but as most motors these days have pretty efficient valve stem seals anyway (unlike the B44) I reasoned that all a flood of oil down the stem would do is make the bike smoke. Which it didn't when I ran it.

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Re: Valve sticking conundrum

Post by Jeff K » Wed Feb 13, 2019 7:23 pm

How thick is your head gasket, there are several different thicknesses out there, measure it and do not trust that it is ok to use.. Is the head to cylinder lip still stock. No one has milled the head for more compression? What valves and valve guides did you use. Some of the new ones are not a drop in fit and need to be honed to fit for proper clearance. After having a very expensive Norton rebuilt head seize a valve, I only use oil or oil based assembly lubes and not grease. Do not use STP for a assembly lube on the newer valves either. I would do a dry run with clay or what ever you have to check the piston to valve clearance, double check valve timing and check the head gasket and it's surfaces. Also some of the older valves have a rough finish on them. They are ok with cast iron guides, but will chew up bronze guides unless you polish them.
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Re: Valve sticking conundrum

Post by csx355 » Thu Feb 14, 2019 8:08 pm

OK hands up here. I have history with B series unit singles. When I was 16 I bought a Starfire for £150 that sat destitute as a non runner in my next door neighbhor's garage for what seemed like an age before I made the acquaintance of a guy a year or two older than me who lived across the road. He rode a British bike and was obviously a fan of the Police. I knew this because he had painted CI5 on the side panel! God it was amazing being an oily teenage scroat with it all to learn.

Anyway Pete with the C15 (subtle eh?) was a Holmans engineering apprentice and really new his stuff and between us - him actually - we got the B25 running and went out one night two up for an illicit blast. His immortal words are still ringing in my ears -

" Bleedy ell matey - are you sure that this isn't a 500?"

That was shrieked in my ear about 30 seconds before he started slapping me on my shoulder shouting

" Pull the F'ing clutch in"

"Wot" I shouted back in the dark, cold winter night air.

"PULL THE EFFING CLUTCH IN"

I did as I was told oblivious to the change in tone from the until then massively willing engine. We coasted to a stop, fortunetely on high ground and pushed and coasted the blown B25 the few miles home to begin the first of two rebuilds and the start of a long but now sadly distant friendship.

Why relate this? - Because my B44 looks like a Starfire and therefore there is a part of me, deep down, that expects it to act like a Starfire. And the only Starfire that I have experience of conspired to blow it's tits off at every opportunity especially when treated to a rebuild by someone who always questions their methods and doubts their ability.

So on the basis that once is unlucky and twice is downright careless I pulled the motor out again and this time sent it off to Roger at http://rtsracing.com/RTS-bsa.htmlas there was a fair chance that the motor may have originated from him in the first place.

I will let you all know how my capitulation goes.

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