Exhaust Reversion?.

[Bevel bob]

Since i fitted a free flowing bigger bore silencer( which seems to have released power) i have noticed a lot of fuel staining on the toolbox ,blowback from the carb. I assume this is not helpfull and am looking to cure this. Thinking of a dam in the header pipe,but don't want to ruin a perfectly good pipe to no good result,has anyone tried this?.

[Jordan]

Does it have a long or short intake trumpet?
A longer one might help contain some of the blowback.

Jordan

[Bevel bob]

Hi Jordan, I have the tradditional long trumpet SSI 29D, so I'm thinking maybe a short one or an exhaust mod.

[Harvey]

Giday Bob, I am guessing that the low restriction muffler that you have just fitted, as you say ( which seems to have released power), is allowing for more air, filling the cylinder, so that some is being pumped out before the inlet valve has closed. As the rpm increases the inlet inertia will hold this pressure, till the valve closes. This is pretty normal for a sports cam, so the answer is don't change anything, just keep the rpm higher, where the inlet closing will match the inlet inertia, and the blow-back will stop.