Smokie centre pot

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ogri211
Posts: 146
Joined: Thu Jan 10, 2013 9:38 am
Location: Glasgow Scotland

Smokie centre pot

Post by ogri211 »

My pal has a B model which he bought from a boy who spent a lot of money on it but hardly used it, the problem is there is smoke from the centre pipes and when you open it up it smokes quite heavily from the centre pipe. I was out with him yesterday a run he has now done about 700 miles on the bike and it seems to run good apart from the smoking, I fitted Accent ignition for him which I also have on my own bike and it runs better. We swapped bikes to do a comparison and I noticed right away his bike doesn't pull as strong as mine through the mid range, and he also pointed out that mine revs a lot quicker, the engine on his bike was rebuilt by Phil Jones, and I done my bike myself with Chriss Appleby doing my crank, one thing I thought about was when I got my carb overhaul kits all 3 main jets were the same, I of course used one of my old jets to replace the centre carb with the correct 107.5 , if my friends had 3 jets the same could that cause the smoking and the slight loss of mid range, any other suggestions greatly appreciated.
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teazer
Posts: 1035
Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Smokie centre pot

Post by teazer »

Main jet a little larger is unlikely to be the cause, but it's not too hard to change to see if it is. Use only genuine Mikuni jets and needles. If your mate's bike has an aftermarket jet kit in it, it should be replaced.

More likely is a weeping check valve in the oil injection system. Check that when the carbs are off for jetting.

Older model GT's had an issue with the oil seal on the center cylinder moving out of place. The design was changed to a seal with inbuilt locating ring, but if the crank was rebuilt with a seal without that ring, it may be the issue.

If the bike is stock and has the SRIS in place it is possible that the crankcase feeding the center pot is the one with a weeping check valve and the excess oil is being pumped from that to the center pot.

I would suspect it's the oil feed check valves.
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