I have a fully restored carb by Martyn Bratby ,beutifully machined . The issue is that its a 389 with a 1 1/8" bore . The standard carb is 1 1/16" . Its not a simple change as other components will need a little work. The bike is fitted with a filter system and Higher than std comp pistons from a 650. . What do you think?.
No trouble at all. You may…
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Carb slides
Hi Robert,
If the 389 has a standard Atlas No.3 slide, you will possibly find it will run a bit rich at part throttle- my 650 certainly did (but I have twin 389's on my 650). I'm sure I have similar settings as Howard mentioned, but I had to go to 3.5 slides to get it to run well.
Regards,
George
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I think mine has a 31/2…
I think mine has a 31/2 slide so should work .Will probably still run a bit rich due to the very close tollerances its been built with.
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the carb starts well and has…
the carb starts well and has a very reliable slow idle ,so that a big improvement. I do notice a slight loss of mid range urge and am wondering if a slotted sleeve ala 650ss introduced after the by pass jet would increase the air speed thro the carb and help a bit.
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No trouble at all. You may have to play about with choke and throttle cable lengths but it will work great. You didn't mention air filter - obviously if you have one for the 376 body it will not fit the 389 body directly. Try a 250 main jet, 25 pilot , 106 needle jet and posn 4 on the needle. I had those settings on a low tuned T110. Good luck Bob, Howard