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Le mans 4 flooding issue.

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andysnapdragon View Drop Down
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    Posted: 15 Jul 2018 at 17:31
my lm4 will start and run well at idle for five minutes or so then it starts to misfire when revved. The plugs are black and sooty when checked. 
The timing, valve clearance and jet size all appear OK. Any ideas?
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GuzziPaul View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GuzziPaul Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jul 2018 at 15:58
Based on my experience in the other thread I would go for:

1.Choke cables badly adjusted, too tight, slacken them right off.
2. Mixture screw too far out, try half a turn in.
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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jul 2018 at 10:53
could also be ignition misfiring. 

"Chicken nuggets don't dance on a Tuesday."
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andysnapdragon View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote andysnapdragon Quote  Post ReplyReply Direct Link To This Post Posted: 03 Aug 2018 at 11:36
thanks..the choke cables and the mixture screw check OK and the ignition timing appears OK but I will recheck.  
Looking at the carbon float it looks like someone has bent the needle arm so, although the float height is correct, the needle does not appear to be closing off the fuel.I will check this theory soon.
Thanks for your advice....
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LarsW View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LarsW Quote  Post ReplyReply Direct Link To This Post Posted: 06 Aug 2018 at 08:59
Are there tiny ventilation hoses fitted? If these are kinked air will not escape from float bowl and floats will not rise, needles will not close etc.....

EDIT: Read your post again and don't think think this is the cause of your problem. Often worth to check, though.


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Lars W
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 06 Aug 2018 at 10:01
Pull the "choke" plungers out and inspect the sealing rubbers. They can be worn or split. At least that will be one possibility eliminated if they are OK.

Has this malady just suddenly appeared?
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