noggin
2nd Class Ticket
Posts: 34
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Post by noggin on Dec 20, 2008 13:53:12 GMT
50 Special with Polini 75cc kit, Polini pipe and 16/16 carb. Runs for a couple of minutes then dies,at low revs, and won't start again. I have set the timing 16 degrees BTDC, gapped the points, changed the condensor, changed the coil, tried jets from 74 upto 85, cleaned the carb several times, adjusted the carb settings until it is idling fine. Any ideas lads?
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ets
High Number
Posts: 113
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Post by ets on Dec 20, 2008 17:27:01 GMT
NGK plug? Try a different spark plug. I heard sometimes NGKs can be faulty.
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noggin
2nd Class Ticket
Posts: 34
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Post by noggin on Dec 21, 2008 12:16:55 GMT
Cheers ets. Yes itis NRK plug, however I have tried several new plugs with no joy.
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Post by skrappey on Dec 21, 2008 17:51:08 GMT
Check the piston rings, could be something silly like they're upside down, don't laugh. Starts and runs for a bit until warm. Something is expanding and you're losing compression, won't run without compression. Fuel problem, pinched pipe, tap not working properly, tank not vented. check all, has same effect as previous idea.
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Post by skrappey on Dec 21, 2008 17:51:57 GMT
Or plug lead breaking down under load.
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noggin
2nd Class Ticket
Posts: 34
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Post by noggin on Dec 21, 2008 19:54:30 GMT
Cheers scrappy. It does appear to be losing compression (flywheel feels very light after engine cuts out) HT lead has been changed. I'll look at the tap when I get chance. Fuel line is new and looks fine, no kinks and not too long.
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Post by joey on Dec 21, 2008 22:38:29 GMT
Sounds like fuel not getting through to me, it'll run for a minute or two with the fuel thats got into the bowl but then not filling quick enough to keep it going. Take your fuel pipe off the carb and see if you have a decent, constant flow, if it runs and then stops take your filler cap off and check again.
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noggin
2nd Class Ticket
Posts: 34
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Post by noggin on Dec 22, 2008 16:12:09 GMT
Cheers, will check it out.
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