mbate
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| posted on 15/1/09 at 09:02 PM |
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twin 40 weber expert needed
Help, I've got my SVA test on Wednesday and my 1600pinto running twin 40 webers seems to be overfuelling, it idles ok but when you start to rev
it ,it sounds like it is overfuelling and black smoke is observed from the exhaust , I set the fuel regulator to 2.7psi and try setting the mixture
but can't get it below 6%
Any advice would be greatly appericated
Mark
Happy to Help
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flak monkey
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| posted on 15/1/09 at 09:10 PM |
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It will be down to your idle jets being too big, they also control the progression phase in webers. So it might be a bit late for the sva....
This could be solved by increasing the air bleed hole size, or reducing the fuel orifice size.
To find out what you have, take the jet cover off the top and unscrew the solid topped brass screws. These hold the idle jets. Take one out and see
what numbers are stamped on it.
You will also always see some black smoke when jabbing the accelerator when you have sidedraughts as they have accelerator pumps in which squirt
excess fuel in under heavy acceleration to prevent the engine leaning out.
Sera
http://www.motosera.com
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mbate
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| posted on 15/1/09 at 09:14 PM |
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quote:
Originally posted by flak monkey
It will be down to your idle jets being too big, they also control the progression phase in webers. So it might be a bit late for the sva....
This could be solved by increasing the air bleed hole size, or reducing the fuel orifice size.
To find out what you have, take the jet cover off the top and unscrew the solid topped brass screws. These hold the idle jets. Take one out and see
what numbers are stamped on it.
You will also always see some black smoke when jabbing the accelerator when you have sidedraughts as they have accelerator pumps in which squirt
excess fuel in under heavy acceleration to prevent the engine leaning out.
The numbers stamped on the jets are 45 F9 does that sound right?
Mark
Happy to Help
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caber
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| posted on 15/1/09 at 09:20 PM |
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Probably needs re-jetting. I am struggling with twin 40s on my Pinto 1600 at the moment I am a bit low on power and have tried changing chokes however
this causes huge progression hole but it really kicks when you get over 4000 RPM.
I am out of the country otherwise I would look out the recommended jetting. You need to pull all the jets, emulsion tubes chokes and write down all
the numbers on them once you have this info you can start to figure out what to change. Jets are pretty cheap on Ebay, Emulsion Tubes and chokes are
much more expensive so keep your fingers crossed.
http://joltfreak.tripod.com/id28.html
this is link to Dave Andrews excellent article on the subject of tuning DCOE carbs
Good Luck
Caber
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mbate
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| posted on 15/1/09 at 09:25 PM |
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Thanks Caber, great find
Mark
Happy to Help
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britishtrident
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| posted on 16/1/09 at 11:59 AM |
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I would guess if it is that rich you want to run a 40F8
Jet codes are
Weak 40F8 -> 40F9 -> 45F8 -> 45F9 -> 50F8 Ritch
Fairly obviously an a 45 jet has a bigger main fuel metering hole than a 40 ----
A **F9 jet is richer than a **F8 jet at the upper end of the idle jets range.
You need to check the main jet sizes also 115 to 125 is the range you should expect to see --- 115 if your engine is unmodified.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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