 Gerryg
TR1 Board Newbie
Posts: 8
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I have been talking to a guy who ran Yamaha Race Bikes in the 80's, they used and tuned diaphragm type carbs.
He was supplied parts and build sheets direct from Yamaha and consequently he's one of the few people with good facts from the era.
To change needle slide responses (mixtures and oscillation problems).
They reduced the slides vacuum feed holes flow by placing split pins, of different sizes, in the holes to reduce vacuum flow.
Also they detailed restricting the outflow from the top of the diaphragm chambers to increase back pressure and reduce needle oscillation frequency.
Plus another mod he used was to put a balance pipe between the two carb adapters, as used on some British sports cars and vertical twin bikes,
I didn't think it would work on our V Twins as inlet valve overlap could destroy each cylinders vacuum.
My engine has standard cams and I have installed balance adapters and a connecting tube. NOTE. It does not have a standard exhaust or intake system. Plus it has the American supplied replacement diaphragms which don't damp as well as the originals.
It seems to have smoothed out the engine and got rid of the flat spot created by needle slide oscillation. The slides rise slower and smoother.
I don't know if my mod will work for others but it gives thoughts for improvement and is cheaper than the Mikuni conversion.
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TR1 engine Carburation problem (Read 2915 times)