I've been doing some work on my engine recently, 5 year rubber replacement, all new hoses and new engine mount rubbers. I've also modified the crossover [compensation] tube as per SI-912-020R1. This allows the use of a hose clamp pliers to close off the tube for easier carb balancing instead of having to remove one end of the tube. The vacuum gauges attach to nipples in the manifolds. I've also fitted the new type flywheel for easier starting.
Unfortunately, when I clamp off the crossover tube at 2000 rpm for carb balancing the engine shakes so much that fuel starts to spill out from one or other carb overflow tube. With the clamp in place this shaking happens up to about 2900 rpm, at 3000 rpm and above it's not noticeable.
With the clamp removed, the engine seems to run normally at all rpm.
I eventually got the carbs balanced by only clamping the crossover tube for a couple of seconds to get a reading and unclamping before the carbs overflowed.
I initially suspected dirt in the carbs from the new hoses, but I've had each carb off for cleaning twice and no visible contamination found.
I have the new style fuel pump, fuel pressure 0.39 Bar, fuel return line fitted. Just fitted all new spark plugs, no change.
Carbs were fully serviced 1 year ago.
Any ideas or advice appreciated.
Unfortunately, when I clamp off the crossover tube at 2000 rpm for carb balancing the engine shakes so much that fuel starts to spill out from one or other carb overflow tube. With the clamp in place this shaking happens up to about 2900 rpm, at 3000 rpm and above it's not noticeable.
With the clamp removed, the engine seems to run normally at all rpm.
I eventually got the carbs balanced by only clamping the crossover tube for a couple of seconds to get a reading and unclamping before the carbs overflowed.
I initially suspected dirt in the carbs from the new hoses, but I've had each carb off for cleaning twice and no visible contamination found.
I have the new style fuel pump, fuel pressure 0.39 Bar, fuel return line fitted. Just fitted all new spark plugs, no change.
Carbs were fully serviced 1 year ago.
Any ideas or advice appreciated.
