Backfire through carb
Advanced
Joined: Oct 2011
Posts: 70
Likes: 8
From: Oildale,Ca.
easy to check this by introducing compressed air into the cylinder through spark plug hole.
on comp stroke ( both valves closed) you shouldn;t hear any air through intake or exhaust.
you can rotate the motor and note when the air comes from exhaust or intake referencing to the timing marks on flywheel.
this will give you an idea of valve seal, cam timing.
sneeze through the carb is usually a lean mixture or too advanced timing- so if you have ruled those out proceed.
the SU can be a great carb as it is a constant velocity type- if your keihin is a 1990-2006 type Keihin CV you have an upgrade...if you have the earlier keihin butterfly carb...oops.
for accurate timing you need the gear lash to be correct for the cam, idlers and timing gears.
I use an EBeyond 2000 sensor- it works with 6 or 12 volt systems and is maybe the best money I've spent on upgrading my FLF--- in the past I had problems with crap condensors allowing my points to arc and pit.
Not no more. install takes minutes, uses stock coil
Mike
on comp stroke ( both valves closed) you shouldn;t hear any air through intake or exhaust.
you can rotate the motor and note when the air comes from exhaust or intake referencing to the timing marks on flywheel.
this will give you an idea of valve seal, cam timing.
sneeze through the carb is usually a lean mixture or too advanced timing- so if you have ruled those out proceed.
the SU can be a great carb as it is a constant velocity type- if your keihin is a 1990-2006 type Keihin CV you have an upgrade...if you have the earlier keihin butterfly carb...oops.
for accurate timing you need the gear lash to be correct for the cam, idlers and timing gears.
I use an EBeyond 2000 sensor- it works with 6 or 12 volt systems and is maybe the best money I've spent on upgrading my FLF--- in the past I had problems with crap condensors allowing my points to arc and pit.
Not no more. install takes minutes, uses stock coil
Mike
Thread
Thread Starter
Forum
Replies
Last Post
