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#854278 07/21/21 3:09 pm
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I’ve had my twin-carb (Wassell) '68 A65 for 3 years (I don’t use in winter), and it’s never needed any choke, but carbs always needed flooding hot or cold for good start.

Over winter I fitted new valves/guides/springs with seats re-cut. Fired second time (no choke) and went on a 20 mile test run with no probs. Next day wouldn’t start, and found that max. choke was needed to start and run until hot (then ticks over ok), this was during present hot weather (90f). It’s been the same after several starts whilst in garage (with door open!). So, I wonder if anyone has suggestions why this is.


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Idle circuit plugged with crud from the float bowls from last years dried up fuel.
Clean both the idle circuit and the float bowls.

Last edited by Semper Gumby; 07/21/21 4:10 pm.
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How old is the fuel in the tank? Sounds like with the hot weather the light ends of the fuel have evaporated which assist with starting and combustion in general. When you have got the bike running. Can you grab hold of the float bowl or is it hot to touch?


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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I did clean out one bowl/filter due to a small amount of ptfe tape fouling the float needle, so will do the other one, and the pilot jets.

Yes there is some old fuel still in (I transfered it to cans on lay-up), but it did run ok on the first run.

I'll check the float bowl temp again. When I first got the bike it used to misfire when hot and eventually I found this was due to overheated bowls, so I fitted some 10mm tufnol spaces along with stainless mounting studs (poor conductors) which cured the problem.


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Should be fine with 10mm spacers, anything bigger than 1/4”(6mm) is fine. Did you get your studs from Motalia? I get mine from them.

I usually find I need choke to start from “cold” even on a hot day. But by the time I’ve pulled out of the end of my estate it’s fine and I can take the choke off. With choke it’s either on or off, because it’s a choke slide and not a butterfly choke soon as the choke slide is within the throttle slide it is essentially off. Least till the slide exposes it again.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Studs- I happened to have some 5/16" stainless rod (not sure what grade but it is hard) and a BSW die, so I made them to length then polished up the end. I also made the spacers as I happened to have a piece of 10mm tufnol. Any thicker, the air cleaners would foul the side panels. Never had that problem with my first A65 ('66 spitfire) as it had matchbox float chambers.


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Originally Posted by semprini
Studs- I happened to have some 5/16" stainless rod (not sure what grade but it is hard) and a BSW die, so I made them to length then polished up the end. I also made the spacers as I happened to have a piece of 10mm tufnol. Any thicker, the air cleaners would foul the side panels. Never had that problem with my first A65 ('66 spitfire) as it had matchbox float chambers.

That’s concerning. There are no threads that I know of on an A65 that are BSW. unless you mean BSF? BSF into the head and BSCY (or CEI) for the nuts.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Allan G #854384 07/22/21 11:08 am
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Yes sorry, BSF!! I then bought some nyloc BSFnuts. The studs are threaded all the way.

Last edited by semprini; 07/22/21 11:09 am.

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Originally Posted by Rocketman71
In my opinion, if perfectly tuned, you should need the choke to start when cold, but not when warm or hot. Perfection is difficult to attain with these crude AMAL instruments, The only solution is to tinker and learn your own bike. Get it close, learn starting ritual, and enjoy. Refurb of head has made it more efficient maybe.

Of course, I am only an opinionated geezer.

That's a likely reason, the engine is more efficient. The valves and guides were well worn and springs below spec.


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Test ride today and running like clockwork. Full choke to start, gradually reducing over 2 mile or so.

I was baffled initially by the fact I've never had to use choke before, so the top overhaul has fixed that.

2 minutes after returning, I measured float bowl temp which was 39/42c and plug temp 128/126c.

Next job is to change oil. Thank you all for suggestions.


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