The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Amal, Carburation, Fuel => Topic started by: Andreas Larsen on 28.05. 2014 18:59
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Hey guys,
It's been a little while since I last posted and the A10 is now firing great thanks to a replace of the springs on the ATD unit and a clean up of the contact breaker and timing set right.
Today I was out riding since the weather here in Denmark has been great, but after about ten miles the engine cut out on me at about 30-35mph - had been going steady speed around that for a couple miles or so. When I pulled over I tried tickling the carb but nothing happened for a good 10 seconds (could have been less), but then the petrol came out like usual. So I'm suspecting that the float may be sticking in the closed position (or the needle is)? But before I go on about buying spares or anything I just wanted to get a few thoughts. And if it sounds about right perhaps a few tips as to how it can be fixed. *smiley4*
As a side note the same thing with the slow tickling happened when I was starting the bike up before leaving.
It's a 376 mono, and it's got one o' them plastic floats.
Cheers
Andreas
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G'day Andreas, first check the vent in the tank cap then any filters in the line/tank/carb and also the condition of the hose. E fuel may have eaten them.
Cheers
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Check your fuel filter too. Maybe it is slightly clogged and your "wait" time was just the result of a bad filter slowing fuel delivery? May be too simplistic, but.....................
Joe
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I have changed the fuel hoses and also cleaned the filters about two weeks ago (I had the problem before this and thought the change might help it cause the fuel lines were starting to crumble). Double checked the carby filter today and it was clean.
I have fitted one of those fancy pants tank caps with a key in it, because I'm a bit neurotic of anybody being able to open the petrol tank. I'll try and slap on the old cap and see if that helps.
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If you decide to fiddle with the carb I would advise fitting a brass, viton tip needle They seem to be less prone to sticking.
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I'll keep that in mind, thanks! Just checked the Amal site and they are not really that expensive.. I'll end up paying more for shipping. *conf* Is it worth changing the part where the needle sits along with it, pardon I can't remember the name of it?
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Andreas, a viton tipped needle and stay up float might indeed be a wise investment if you're suspecting trouble in that area. I'm not a fan of these flimsy plastic needles neither.
If the petrol level in the carb is effectively getting to low this means the needle seat should be ok, as no petrol is getting past the sticking needle, so I wouldn't change the seat. Just change the needle and see what happens
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However, a good soaking of the seat in carburator cleaner and swabbing out with a Q-tip might be in order. There could be deposits that are contributing to a sticking needle.
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Thanks for the tips, I'll have a look at it as well when I get the new needle.
A *smiley4*
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Been a little while and I thought I'd do an update.
I changed the float needle and checked the fuel lines and also the little breather/air hole in the petrol filler cap and also cleaned out the carb real good, and to top it off I readjusted the gaps on the spark plugs, cause I'm not sure, that if the gaps are too wide, the heat will make them loose conductivity and thus making it harder to spark and then stall? (not sure if this is true but the gaps were a bit too wide all the same). All of the above seems okay and the carb is now tickling over with ease.
However....
When I started it up it seems like it's idling on one of the other jets, since it just seems to me like it's running on way too high revs at idle - and when i try to adjust the screw on the carb it can only go so far down revs, but nowhere near where it was before - and before I took it apart I could almost get it to cut out by screwing it far out (never tried actually killing the engine this way, so not sure if able to). Anyways, can the cutaway slide be sticking somehow and be in need of a polish or is there something I might have missed?
And also *smile* is there any sneaky way of adjusting the air mix without removing the exhaust? Sadly the bolts holding the exhaust in place are horribly rusty and I've so far not been able to get them loose, it's one of them jobs I've been pushing in front of me for later. I read somewhere that if I screw in the pilot air screw and then unscrew it 1½ turn it should be about right (I've got an air filter on it so this might not be right in my case)?
Any help or tips would be awesome!
Cheers
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Morning Andreas, when you replaced the carb did you check the cable run ?,could possibly be that the cable as changed position .If you have an adjuster on the cable slacken it a bit and assess results ,also before starting check if it feels free .If no good at least you have eliminated one poss problem and can concentrate on other adjustments . Don't adjust to many things at once stick with the carb ,then points etc after listening to the results ,that way you can always go back to "as was " and look for something else . Which strangely has just come me check the carb manifold joint for a poss leak ,that would I think mess up adjustments , cheers BobH.
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I'd put money on that Bob.
Andreas.
Here's a good site for tuning tips http://www.hitchcocksmotorcycles.com/hints-tips-monobloc
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Thanks guys, I'll have a look at it tomorrow or the day after. I've got a spare gasket for the manifold lying around, so might try changing that and see what happens - do you use any gasket goo or silicone for that or just use as is by the way?
And thanks for the link muskrat, great site that *good3*
Andreas