The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Amal, Carburation, Fuel => Topic started by: Liakos1982 on 23.04. 2015 21:16
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Hi, I took my carb off to clean, investigate some potential starting problems. I was wondering if it might be a good idea to replace the spacer between the carb to something more thermally isolating? Any ideas on this, I feel like it might allow for easier starting of a warm machine? See my attached photo, should this be replaced, changed with something else?
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G'day Liakos.
That looks like the normal tufnol insulator. If you feel it's not enough you could try two but the studs may not be long enough.
Cheers
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I have not tried removing them but those studs can be replaced right?
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They can be. But in reality I wouldn't bother unless your running a really hot motor. My alloy head A7 only has a paper gasket with no heat problems at all.
Cheers
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I had the problem of slide sticking open before discovering the valve timing was way out (told many times by the wise and enlightened here) causing a very hot motor. Since putting things right the motor runs cooler and no carb' problems with sticking slide. I don't have an insulating spacer either just a fairly thick gasket.
Gerry
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1st thing I'd replace is the missing throttle cable adjustment. *whistle*
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I have a two part cable, so the adjustment is closer to the handle bars, I think at least. Would you suggest something different?
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The throttle cable should have a cable adjuster on the carb top the same as the one for the choke,
it will stop your throttle cable slipping down into the carb body...
(as per your picture shows signs of previous doing..)
it will also help to stop air from leaking in on top of the slide..
Possibly a smear of petroleum jelly ( eg. Vaseline) on the O ring?
or a silicone gasket cement if not? to stop air leaking on the inlet side..
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OK very interesting. Thanks for the tip. Could this explain some problems with starting that I am having? I have a totally rebuilt mag from a reputable guy here in Denmark, and she is still hard to start...
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watch out for this gasket hole bigger than spacer hole
http://www.a7a10.net/forum/index.php?topic=8566.msg60841#msg60841
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The throttle cable should have a cable adjuster on the carb top
some of them just have a plain hole and a ferule thingy that stops the cable outer falling in
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Shouldn't have any adjusters on the carby top, just "top hats" for the cable.
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I'm sure you know more about the workings of the carb & BSA's in general more than I ever will Trev.
I was just going by the Amal parts & tune sheet..
What ever the outcome... he needs to eliminate any air leaks.. *wink2*
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"top hats"
yep those are the words I needed, on my bikes I had one of each but who knows how history has intervened
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Wozza,
The A7/10 didn't have carb top adjusters, just the in-line ones.
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They can be. But in reality I wouldn't bother unless your running a really hot motor. My alloy head A7 only has a paper gasket with no heat problems at all.
Cheers
Hi Muskrat,
I am new to the Forum and I was searching about the spacer between the carb and alloy head. I have a 55 A7 engine with an Alloy head fitted, I dont know any more about the engine. but at the moment I have no spacer between the head and (very worn) carb. as I am ordering a new 376 carb I though I would double check if I really should also order a spacer? If so what should I order, a tufnol spacer?
Any suggestions would be appreciated, as I see you seem to have mentioned an alloy head.
Many thanks
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G'day Hughsie, sorry for delay, I've been away to IOM.
Most classic bike shops will sell the insulators (tufnol) in 1/16" or 1/8" thickness. I use 1/8" myself.
Cheers
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Thanks for the reply.
I got one from Hitchcocks in the UK, it's been working great and no issues to speak of.
My next woe is I've been scaremongered by some older locals about my crank bearing causing my engine to seize up.
I was just happy it was now running sweet, didn't really want to pull it apart, but it's playing on my mind now lol.
Will write a separate update in the correct section once I decide what to do...
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G'day Hughsie, sorry for delay, I've been away to IOM.
Most classic bike shops will sell the insulators (tufnol) in 1/16" or 1/8" thickness. I use 1/8" myself.
Cheers
What! Muskrat you've been to the IOM *respect* . Wheres the thread with all the pic's *dunno* of the pilgrimage
Magic place *loveit*
mod edit: http://www.a7a10.net/forum/index.php?topic=8757.msg69141#msg69141
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I've been scaremongered by some older locals about my crank bearing causing my engine to seize up.
two main issues with the crank play
1. end float
2. worn timing side bush
Quick way to check both (well not that quick)
1. End float - remove the primary chain case and the shock absorber arrangement and sprocket from the crank, pull the crank back and forth looking for movement, initial set up is max of 3 thou, obviously with use this may have increased a little.
2. timing side bush - remove the timing side cover, probably best to remove the oil pump, then look for lift on the crank pinion.
Many of these old bikes are travelling along quite happily with a bit of play and a bit of end play, I wouldn't panic unduly, ONOH your probably not going to be happy now until you've satisfied yourself of the old girls condition, if it aint banging to much enjoy it for the time being
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.....and the shock absorber arrangement and sprocket from the crank,.....
No offense Bill, and maybe I'm having a moment, but is it really necessary to remove any of that just to check ?
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I think in a previous post it was stated that the engine shock absorber didn't effect end float as it was a self contained unit not tensioning the crank ,so couldn't you just pull as is in situ to check ? Bob
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Bob Dutch
Yes your quite right, usual bit of brain fog