Author Topic: short bellmouth  (Read 883 times)

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royblackburn1@btinternet.

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short bellmouth
« on: 20 July, 2019, 20:25:36 »
Is there any benefit fitting a short bell mouth to a concentric carb instead of a gauze filter. thanks Roy

chaz

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Re: short bellmouth
« Reply #1 on: 21 July, 2019, 08:55:21 »
theory is the open bell mouth lets air flow, gauze can cause disturbed flow, but, main thing is the filter is there for a reason. when we were racing on ex airfields , despite hiring a road sweeper, they were still dusty places. we had a few bikes pick up dirt into the motor while running without filters.

modern superbikes can be tuned using different intake trumpets lengths BUT still keep the air box and filter. As performance is not really a worrry on most classics I go for safety of filter.

Mike Farmer

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Re: short bellmouth
« Reply #2 on: 21 July, 2019, 10:32:14 »
 :) :)

It may also weaken your basic mixture settings.

Mike 8) 8) 8)

A10 JWO

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Re: short bellmouth
« Reply #3 on: 21 July, 2019, 16:04:48 »
I heard a bit of grit go down my carb 40 years ago, panicked for a while. Days before helmets : )

royblackburn1@btinternet.

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Re: short bellmouth
« Reply #4 on: 22 July, 2019, 01:12:10 »
thanks, filter stays. Roy

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Re: short bellmouth
« Reply #5 on: 22 July, 2019, 06:39:50 »
Bought the A10 in 1972. It has never had a filter. But then in Scotland it ingests rather more rain than dust...

chaz

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Re: short bellmouth
« Reply #6 on: 22 July, 2019, 08:56:39 »
just to add, the T100 has long trumpets with gauze filters, the A10 has no bellmouth or filter and the A50 has a K&N style gauze filter.
my eldest did 3 years at uni doing motorcycle design and engineering, his books (expensive and large) had massive amount of information on tuning with bellmouths , trumpets and filters. infact there are a couple of papers onthe internet with published results on the subject.