Avanti bogging down

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whonatic
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Hi all
Spoke to Ron, changed a few things including needle, atomiser and made no difference. Pilot was 50 not 55 as I previously stated so went to a 48, stayed the same. Air screw was already only 1/2 turn out so that was lean enough.
All that's left is carb change, CDI change, stator change but ultimately throw the old crank back in to see if timings have changed with the new crank??

After this , it's drop it with someone who understands it and get a professional diagnosis !
holty
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did you strobe it as darrell suggested, the keyway could be in a slightly diffrent position on each crank so worth double checking.
whonatic
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holty wrote:did you strobe it as darrell suggested, the keyway could be in a slightly diffrent position on each crank so worth double checking.
Yes, completely redid the timing marks and then arrived to 17
eden
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when strobed is the timing where it should be at low rpm?
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coaster
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Did you do a leak down test on it? worth doing especially as you said you had problems with the drive side seal. The chamfer on some cranks doesn't always allow the seal to slip over with the result that the spring gets displaces from the seal, Definitely worth doing a test to rule it out.

The other thought is that one or both of the rings have become damaged/stuck in the grooves during the assembly so what is the compression like?
Strummer10
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Only a thought.......as i have run an Avanti for 6 years regularly now with not one issue from the kit, BUT i did have a succession of 'off the line' bogging down problems away from the lights which turned out on all 'Three Occasions' (can't believe my luck) to be petrol burning it's way through the sealed joints on my 30mm carb float chambers within the carb and partially filling both floats with petrol......thus flooding it on pull away and up the road until the fuel demand was met i guess.....just another one to check and potentially it could happen on any carb.

Ironically now resolved with a 1980s black 30mm carb float lol....
eden
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The black floats are still available from eurocarb, they are just slightly more expensive than the white ones.
whonatic
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Strummer10 wrote:Only a thought.......as i have run an Avanti for 6 years regularly now with not one issue from the kit, BUT i did have a succession of 'off the line' bogging down problems away from the lights which turned out on all 'Three Occasions' (can't believe my luck) to be petrol burning it's way through the sealed joints on my 30mm carb float chambers within the carb and partially filling both floats with petrol......thus flooding it on pull away and up the road until the fuel demand was met i guess.....just another one to check and potentially it could happen on any carb.

Ironically now resolved with a 1980s black 30mm carb float lol....
Had that when I first built it 3 yrs ago so it's a good shout but unfortunately it's not the case this time :(
whonatic
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coaster wrote:Did you do a leak down test on it? worth doing especially as you said you had problems with the drive side seal. The chamfer on some cranks doesn't always allow the seal to slip over with the result that the spring gets displaces from the seal, Definitely worth doing a test to rule it out.

The other thought is that one or both of the rings have become damaged/stuck in the grooves during the assembly so what is the compression like?

Yes did a leak down on the build using part of Darrel Taylor's kit - no leaks thankfully. I changed the crank as I'd done 3 oil seals! But using the rimini drive side oil plate and a different crank seems to have cured that problem. However , I know I should have changed only one thing so the old cranks going back after Weston.

It's also an absolute tw@t to start !!!!

I can only think that the inlet duration has changed by the smallest amount but is making it crap off the line and 10 kicks to start
eden
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try I known good stator before you swap the crank out.
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