fuel and concentrics

scot · Post by **scot** » Tue Sep 22, 2009 7:38 pm

any answer to the problem i have experienced on two different bikes
i run a g12 with a monoblock with 95 petrolno problem
but on my a65 lightning and thunderbolt with concentrics experience
the needle jet blocking with what seems like lite lub oil which blocks the small inlet holes in the 106 jet then you lose all mid range being two up this is where we seem to run pilot jet is ok main jet is also ok takes about 60 miles or so to block also when striping carbs down toclean air slide an easy to remove varnish on outside and sticky gum on top where spring sits once jet is cleared bike runs ok for some miles then blocks again i run both bikes on 97 petrol i wonder if carbs run to hot and 97 petrol splits and leaves heaver elements behind any answers greatfully accepted

Don Madden · Post by **Don Madden** » Tue Sep 22, 2009 8:47 pm

Is there alcohol in the fuel? You describe a common problem with alky dissolving crud in tank or even plastic fuel lines, washing it into the carb. Cheers, Don.

Yorkie · Post by **Yorkie** » Wed Sep 23, 2009 12:04 am

I run my '72 Bonneville with concentrics on 95 fuel all the time, never had any problems.
Not sure if 97 or higher has extra additives that may cause the problem, have you tried using 95 instead in your BSA's?

rgds, Steve

scot · Post by **scot** » Thu Sep 24, 2009 7:02 pm

[quote]
Is there alcohol in the fuel? You describe a common problem with alky dissolving crud in tank or even plastic fuel lines, washing it into the carb. Cheers, Don.
[/
quote] thanks for info did not know this was a common problem second bike to give same troubel lightning did it in usa ok now after good clean with acetone thought it was only over sprayed paint disolving that time but did it again with shell v max but been ok since clean this time it is pet seal so have cleaned it out will reasemble at weekend maybe it happens to me as i run two up all the time with the needle jet in use thanks scot