Help_carb settings_poor pick up after revving to c.4,500 rpm

Maestro, SEI-V

Help_carb settings_poor pick up after revving to c.4,500 rpm

Postby Seagreen » 21 May 2018 17:20

Hi, I have now got my 500 Morini (imported form Denmark) road legal and running but I am experiencing a problem with the engine not really pulling very strongly. If when stationary I rev the engine to c.4,500 rpm, close the throttle and then open it again, the engine bogs down badly but then picks back up again. Engine ticks over well; I have replaced all the jets and needles with new, sizes as per manual. Float heights measured and within the limits specified, chokes seems to be off. Could it be ignition system (I have read some threads on this forum that raided this suggestion) but I suspect that it is the carb settings. Any suggestions as to where I should look first?
Thanks,
Charles
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Re: Help_carb settings_poor pick up after revving to c.4,500

Postby P.I. Staker » 21 May 2018 17:47

If you have the original solenoid tap, have you tried it on reserve?
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Re: Help_carb settings_poor pick up after revving to c.4,500

Postby Seagreen » 21 May 2018 18:57

Hi PI, would I be correct in thinking from your reply that you suspect weak fuel/air mixture? I have tried the reserve on and off but no real difference.
Thanks,
Charles
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Re: Help_carb settings_poor pick up after revving to c.4,500

Postby 3potjohn » 21 May 2018 20:23

So if you don't close the throttle does it pull through that 4500 limit? Can you do a plug chop when it bogs down and check them out e.g.wet with unburned fuel. I think a flat spot at around those revs is something others have experienced. I've played around slightly with pilot jet sizes to lean the mixture to prevent bogging down when pulling away,but no other issues at all.
There's some info previously discussed here maybe helps viewtopic.php?f=4&t=3901

hope you get sorted.
John
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Re: Help_carb settings_poor pick up after revving to c.4,500

Postby Al B » 21 May 2018 20:32

While searching for hints about my bike's stutter on light throttle after a carb rebuild I've come across threads which indicate modern fuels seem to run richer and therefore need smaller idle jets to smooth the progression.
Another symptom of an over rich idle mixture is a tendency for the engine to nearly stall after blipping the throttle. If you have access to leaner idle jets it might be worth trying.
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Re: Help_carb settings_poor pick up after revving to c.4,500

Postby Seagreen » 30 May 2018 22:15

Hi 3potjohn and Al B,
Thanks for your comments and advice. Sorry to be slow to respond but been tied up with one on my son's wedding arrangements. Now all finished so will be able to get back to investigating the fuelling. Thanks again,
Adios,
Charles
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Location: Cheltenham, Glos


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