featherweight running
Moderators: John@sos, charlesp, Charles uk, RickUK, Petergalileo
featherweight running
I have a late featherweight (an SEF). It has a new head, new plug, and I think I have cleaned out the fuel system pretty well. I replaced the exhaust with one with no holes, but it didn't like starting - so I drilled a couple of holes in the tube, and it was happier. But it really only likes to run on full throttle with max revs. It just won't run when you reduce the throttle - just goes for a few seconds, then dies. The carb is the Amal 416. So any ideas?? My seagulls have always run superbly - until this one, and it is defeating me at the moment!
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Charles UK
Sounds Like fuel problems to me Mark.
Are you running 25:1 fuel mix?
With the fuel tap closed remove the float bowl from the bottom of the carb, now open the fuel tap you should get a medium dribble out of the needle valve.
If that's OK clean all you can, in the carb with two stroke mix/compressed air & try again.
There is a remote possibility that your CDI unit could be faulty, so check for sparks as soon as it stops, normally CDIs are either completely dead or stop after a few minutes when they get hot.
Should that prove the case John should be able to find you an exchange unit but they are not cheap as they are no longer readily available.
Failing that, sell it to me as I think they are one of the best motors Seagull ever made.
Are you running 25:1 fuel mix?
With the fuel tap closed remove the float bowl from the bottom of the carb, now open the fuel tap you should get a medium dribble out of the needle valve.
If that's OK clean all you can, in the carb with two stroke mix/compressed air & try again.
There is a remote possibility that your CDI unit could be faulty, so check for sparks as soon as it stops, normally CDIs are either completely dead or stop after a few minutes when they get hot.
Should that prove the case John should be able to find you an exchange unit but they are not cheap as they are no longer readily available.
Failing that, sell it to me as I think they are one of the best motors Seagull ever made.
I too think they are one of the nicest Seagulls, they are noticably quieter.. I have one for my grandson, runs a dream, bet yours has a fuel problem... Halfords carb cleaner works wonders..
Like Charles's second option, but don't let him talk you into getting rid of it! He will turn it into a racer to replace his 170's! Woner how he got on in NZ???? Have not heard too much yet......
Check the gap on the plug, though that should not make that much difference...25 thou on this one.
just a thought has the top of the flywheel been off? the timing should be fixed but if too advanced might give same effect... see that all is secured as it should be...
Regards,
John
SOS
Like Charles's second option, but don't let him talk you into getting rid of it! He will turn it into a racer to replace his 170's! Woner how he got on in NZ???? Have not heard too much yet......
Check the gap on the plug, though that should not make that much difference...25 thou on this one.
just a thought has the top of the flywheel been off? the timing should be fixed but if too advanced might give same effect... see that all is secured as it should be...
Regards,
John
SOS
Thanks for the quick replies. I will try the carb cleaner first and re-do the checking of fuel flow from tank to jet etc. I hope the CD unit is ok - the engine restarts ok - so hope there's no problem there. Timing - hope that's ok too - I haven't touched the flywheel, but who knows about the past...
Some more detail on the symptoms. When on max throttle its climbs more slowly than it should to max revs, but runs fine. Then you throttle back, the revs fall, she runs for a few moments, and then dies. Then it is a little reluctant to start, but will do so, but struggles then to rev back up again - sometimes just struggling to keep going on low revs. There is no missing - so I guess the plug gap is fine, and I hope that the timing is fine as full power seems reasonable. The engine is not too low in the water - checked for that already.
Hopefully the carb clean will work if that is what it sounds like.
Some more detail on the symptoms. When on max throttle its climbs more slowly than it should to max revs, but runs fine. Then you throttle back, the revs fall, she runs for a few moments, and then dies. Then it is a little reluctant to start, but will do so, but struggles then to rev back up again - sometimes just struggling to keep going on low revs. There is no missing - so I guess the plug gap is fine, and I hope that the timing is fine as full power seems reasonable. The engine is not too low in the water - checked for that already.
Hopefully the carb clean will work if that is what it sounds like.
