The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: morris on 21.09. 2015 23:03
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Ticked the 500 mile since rebuild box on the plunger so thought it was about time to retorque the head.
When taking the rocker box off, to my horror I found the valve stems badly damaged by the adjusters. Paid £60 for 4 new stainless steel valves and they're already good for nothing but the scrap bin *bash* *problem*
They came from a reputable dealer together with the adjusters. Seems the stems are to soft? Or the adjusters to hard? Or something else I overlooked?
If anyone can recommend a good source for a new set of valves, I'll be happy to hear.
Also recently ordered some different size main jets for the carb at another reputable dealer.
They came in a non marked bag and the jets were stamped W****l *pull hair out*
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I hope you are going to chase a refund
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I hope you are going to chase a refund
Will give that a try. You never know...
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If the valves and rocker adjusters came from the same seller I can't see how they could argue about it.
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I had that happen to mine a long time back, and there was a guy with a workshop across the way from guys I knew, and he tipped them with either stellite or boronium- but can't remember if they're the ones I'm currently using *conf*, but maybe worth checking into.
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hi guys, Morris is it possible to get steel caps for them? cheers
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is it possible to get steel caps for them
You mean like on old single cylinder Lister stationary engines CS-3/6...??
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The steel caps are called 'lash caps' and they used them on A7LS. I've never had any problems with the valves I sell and I always refund on the rare occasions customers are unhappy. I have Wassell main jets in a couple of my bikes. When I've been trying to alter the main jet mixture ratio I find that the Wassell main jets function the way you would expect, i.e. fitting a bigger jet than the original Amal makes the mixture richer etc.
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I trust in German engeenering an use this tappet adjuster as shown in the picture.
The power that get to valvlestem is a distributed force.
The `lashcap`is build as a bolw bounded in a ball. All the moving from the rockers are eliminated in this item.
No vertical forces at the valve guides.
It`s hard for me to explain, but I think you`ll understand.
cheers Klaus
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That looks clever. Where do you get them?
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That looks clever. Where do you get them?
It`s Mercedes Benz Partnumber A102 050 02 20 ask at a MB Dealer and order the nuts also
The thread is M 8 x1 but similar to the britsh cycle thread, but it `s easyer to fit with a metrish recut.
If the valve stem is damaged you can grind or cut it shorter, so you have more clearence to tune.
Cheers Klaus
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Like the part. Not crazy about modifying the rockers.
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klaus is showing off his elephant foot adjuster . triple owners use the porshe variety [expensive]also with lashcaps. another option is mushroom headed adjusters with lashcaps which i use on my triple without problems.i believe, but not possitive, the pre unit triumph used the same valve adjuster thread as the a10 but you will have to remove the rocker box to fit them.
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My beesa triple runs lash caps and mushroom tappets, the triples rev far beyond any twin and the triples rocker geometry is very hard on the valves.
its not uncommon for singles or twins valves to burr at the top and need a light file to remove from the guide without damaging it.
Not that they should spread or mark under low mileages.
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Thanks lads. Gives me a lot to think about
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The steel caps are called 'lash caps'
That's the term I had in mind (didn't)... *smile*
That looks like a handy piece of kit Klaus... *wink2* ..but also Like the part. Not crazy about modifying the rockers.
...Also gives extra tappets in the cups and balls... *fight*
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...Also gives extra tappets in the cups and balls... *fight*
Is that something to look forward to? *whistle*
Richard L.
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or that given BSA used almost every thread form known to mankind is the rethreading of parts to metric forms a natural progression or heresy? *eek*
I'd err towards burn the heretic *whistle*
Just as well we're a diverse bunch *wink2*
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I'd err towards burn the heretic *whistle*
.....hhmmm *conf*
I kinda like the idea of roller rockers...but that's not why I'm here; No work today, so figured I'd check the clearances- in@0.009 /ex0.012 might close the ex to 11...but that's also not why I'm here...
While doing this check I remembered that the way to do the clearances on my '69 Daytona was to close the adjuster in to zero clearance, and then wind it out something like a quarter turn, to give whatever it should be maybe ~7-8 thou *dunno2* ...sounded a fairly dodgy at the time, but have since figured that depending on the thread pitch (maybe 1/4bsf on that?), seems logical, so I've applied that logic to the A10 and wasted time over a cold tongue lube :P, and created a tool which I'll paste later........but that's also not why I'm here....
I had a thought, and another look at Morris's photo, and going by the shape of the indents it kinda looks like maybe the rocker geometry could be a bit wrong, maybe the pushrods are too short/long, (could be a consequence of gasket thickness?) and also maybe the thackery/shims are a bit flaccid...
I asked about rocker geometry awhile ago, but can't remember any outcome..??
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I had a thought, and another look at Morris's photo, and going by the shape of the indents it kinda looks like maybe the rocker geometry could be a bit wrong, maybe the pushrods are too short/long, (could be a consequence of gasket thickness?) and also maybe the thackery/shims are a bit flaccid...
I asked about rocker geometry awhile ago, but can't remember any outcome..??
A mate sketched these notes up for me for checking my a75, which is slightly different but are very sensitive to rocker geometry for valve wear (typically stems and guides) , but the intention was that at half lift the tappet should be in line (at 90 deg) with the valve stem. Not sure how to best articulate this.
With the A10's and A7's having various cam lift and some with after market pushrods or skimmed heads or differing gaskets its quite likely mainly are not quite optimal
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I'll look at the pics later, but; at half lift the tappet should be in line (at 90 deg) with the valve stem. Not sure how to best articulate this.
It's the same principle as brake/clutch cable geometry...??
With the A10's and A7's having various cam lift and some with after market pushrods or skimmed heads or differing gaskets its quite likely mainly are not quite optima
l
Yep I'm inclined to degree to agree- *whistle*(sorry-just had a play on words there).....but also I think you mean likely many are not quite optima
..?
It kind've makes sense that if there's a bit more lift involved, geometry will change some- depending maybe on the base radius *????*
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A little update. I think the adjusters where to pointy and to hard as well. Tried to give one of them a couple of file strokes but that didn't even make a scratch on the surface. Don't understand why they have to be that hard. After all, they're a lot easier to replace than a valve.
I have ordered a set of adjusters at another supplier (bottom of the picture). They have a much flatter surface and are softer to.
The valve train seems to be a lot less noisy now. Gonna run it for a while like that and see what it does.
hi guys, Morris is it possible to get steel caps for them? cheers
Yep. B31 valve caps fit. I ordered a set but decided not to install them for the moment
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hi morris, do you mean b31 lash caps fit the a10 valve. if thats a yes i may use them with mushroom adjusters myself on my next project.
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hi morris, do you mean b31 lash caps fit the a10 valve. if thats a yes i may use them with mushroom adjusters myself on my next project.
Yes, tried them on and they fit. B31 stems have exactly the same diameter as A10's
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The problem with fitting lash caps to valves not designed for them is the added length to the stem and the geometry to the rocker.
Cheers
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yes muskrat your right but there might be space to grind down the valve stem, use slightly shorter pushrods or even worn cam followers would compensate.no harm in experimenting if you like fiddling.