hi all, since i have made a new manifold, for my bike carbs and put a new air filter on it, i get a poping/backing firing at the carb end, from seems to be the outer 2 carbs, what would cause this?

lack of fuel or to much air or something else?

your throughts please

thanks

stuart

[Edited on 16/3/09 by Stuart_B]

Spitting back through carbs/throttle bodies is usually down to two main things:

1 the mixture is too lean

2 the ignition timing is wrong (too far retarded)

If you havent fiddled with 2, then it will be 1. It could be the new air filter is much freer flowing and letting more air through so its now slightly lean.

You may be able to adjust it out with the idle mixture, depends how the carbs work.

David

[Edited on 16/3/09 by flak monkey]

As above ^ can't really add anything to that

inlet manifold air leak? spray wd40 around the manifold and see if the revs go up

bike carbs tend to spit back when the engine is cold

this may help you

quote:

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http://www.locostbuilders.co.uk/viewthread.php?tid=106664

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Are the carb throttles properly synched ?

hi, thanks, i will check the timming tuesday, and check for leaks. as well, well when i had the carbs on before there was no back fire, so not sure about if they are properly synched, but they where fine.

could i use rubber as a gasket if it is not sealing up enough against the head?

thanks

stuart

buy a sheet of gasket material and make one. Seal it with the gasket sealer / bonding stuff you can buy.