Author Topic: Any suggestion please  (Read 1136 times)

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Hancock

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Any suggestion please
« on: 14 July, 2018, 12:11:53 »
Hi I can start the bike ok B40 I can only keep it running by keep Reving the engine withthe revs quite high. If I stop Reving then it dies.i also get the occasional back fire.

AdrianS

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Re: Any suggestion please
« Reply #1 on: 14 July, 2018, 12:32:46 »
How long have you had the bike?
Has this problem just started? Does the bike run OK until you let it idle?
Could just need the carb setting . Have you tried turning the idle screw in a little and then setting the idle mixture?
So many things can cause these symptoms!

hoogerbooger

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Re: Any suggestion please
« Reply #2 on: 14 July, 2018, 13:50:01 »
agree. more info needed

indicate what you've checked e.g for air leaks; condition of carb; crap in fuel

I had an almost similar problem with my B40 of not being able to get it to idle and having to hold the throttle open to keep it going and a bit of spitting when I throttle down. But it had idled ok not long before having just put it back together............turned out to be the air filter shaking itself off and affecting fuel fuel mix




I knew my fuel and carb should be clean, but was advised didn't need much.   I didn't think I had air leaks at the engine manifold or too much wear in the carb


too much wear on the throttle s


I didn't think I should have air leaks

Hancock

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Re: Any suggestion please
« Reply #3 on: 15 July, 2018, 10:17:21 »
Had bike 6months or so . Mate of mine said he recons the carb could me dirty due to modern fuel sat in it for a few heard before I had it. He suggests getting the carb cleaned by someone with a sonic tank.

AdrianS

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Re: Any suggestion please
« Reply #4 on: 15 July, 2018, 10:45:52 »
The Amal carbs are easy to strip and are quite simple things. Strip it down and unscrew the brass jets. These can be blown through with carb cleaner and compressed air, so can the carb body. My experience is that the bikes will run ok with quite worn carbs.
Lots of info about them on the net. Google Burlen Fuel Systems as they sell the carbs and all the parts and there is a lot of info on their site re setting up etc.

Hancock

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Re: Any suggestion please
« Reply #5 on: 16 July, 2018, 14:23:22 »
Thanks for your help .i was looking at buying a carb repair kit it’s only 25 pounds or so. It asked for main jet needle jet and primary jet sizes . How do I find those out.

JulianS

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Re: Any suggestion please
« Reply #6 on: 16 July, 2018, 15:11:41 »
Should all be in the owners manual or service sheets, but if you dont have access to these and presuming you still have the original monobloc fitted, below is from the 1965 owners manual.

Hancock

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Re: Any suggestion please
« Reply #7 on: 16 July, 2018, 15:41:38 »
Thank you mines a b401962 would that be the same. Also on the top of the carburettor there’s access for two cables throttle and air. I don’t have an air adjusting cable should that be blanked off or just left open. Thanks for your help once again.

JulianS

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Re: Any suggestion please
« Reply #8 on: 16 July, 2018, 17:33:57 »
Same for 1962 models.

I would blank off the air cable hole if you can.