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Balancing air flow to twin carbs, by the height of a straw in each dashpot. Is this an accurate measure of the air flow to each carb?


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Hi. I was wondering about this known method. It could give an accurate measurement of the needle height , though maybe not necessarily the air flow into each carb, as the pistons may have different sliding resistance due to wear etc.

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yes there are or were simple height meters made to do just that 

think we discussed any means to check the idle running height of the air piston is a good practical 

test  idea 

far better than trying to listen to the air hiss  which doesnt do much 

Pete

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in the day you just set the idle screws at the same turns ,and bunged them on , no faffing about with air flow malarkey simple basic mechanical set same as 

as jonny says  as soon as you open the throttles its game over for any "balancing" 

Pete

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50 minutes ago, johny said:

Also I think any slight difference at idle passes into insignificance as the butterflies open up more when driving....

 

46 minutes ago, Pete Lewis said:

as jonny says  as soon as you open the throttles its game over for any "balancing"

Thanks guys. I had sort of forgot that! 

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When I had my spit tuned on a rolling road the guy had two modified dampers screwed in the top of the dash pots which had sliding scales so he could see the piston hights for both carbs.

Danny

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Bit like setting throttle valves with a fag paper, or torqueing down bolts by feel.   It can be down, with enormous experience and skill, but for the rest of us, there are MUCH better tools!  Look for "synchrometer".

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11 minutes ago, johny said:

Not a bad idea but dont know if flow meters can handle that....

Mine did and it's the common German made one on sale on eBay etc. our engine capacities are relatively small.

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7 minutes ago, JohnD said:

It can be down, with enormous experience and skill, but for the rest of us, there are MUCH better tools!  Look for "synchrometer".

I agree!

By the way John your suggestion of using O rings to stop oil seeping out of the rocker cover fixings worked a treat Ta😁

Iain 

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In my case no but it may for other engine setups.

With my downloaded wsm I have now renewed my relationship with my carbs....🤪

 

Edited by Iain T
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1 hour ago, Iain T said:

I agree!

By the way John your suggestion of using O rings to stop oil seeping out of the rocker cover fixings worked a treat Ta😁

Iain 

Thank you, Iain!

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2 hours ago, Iain T said:

In my case no but it may for other engine setups.

With my downloaded wsm I have now renewed my relationship with my carbs....🤪

 

Yes Ive thought before that on idle the butterflies mech is resting on the throttle stops but at revs they are held open by the cable so may actually go out of the carefully set idle balance...

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