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Discussion Starter #1
I had posted this in the introduction forum and was told to post here.

I just got a 1998 Vulcan 1500 classic. It was parked for 6 years. I have redid the wiring for all lights to work, replaced brakes and tires, changes oil and spark plugs. It has vance and hines two into one pipe with baffle in it.

Now onto the problem, i have rebuilt the carb, adjusted the air/fuel mixture screw about 20 times which means as you all know having to pull the darn thing off every time. I have driven it in between each adjustment. It is know at 2.5 turns out( i have had it as much as 4), bike starts and runs but gets crappy milage. It also has black soot smoke coming out of tailpipe but only at idle and slight throotle. Once you get above that after a few seconds no more smoke. This leads me to think it is flooding very badly at idle. I am lost, any help would be appreciated.

If i missed this discussion in another post, i apologize.
 

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@Kevinb

Soot can mean 2 things, if its black then its oil, if its like a grey'ish colour then its fuel (too much).
If you are running a carb, then dont expect to have fuel efficiency as a fuel injection system.

Now the hard thing with your case with out me being able to look at your bike in the flesh, my guess is try and tune the carb to the right mixture, once you have done that and your still seeing soot, (which im thinking its oil) then your going to have to rebuild your engine as your piston rings etc... are worn out.

A technique that i generally do if i dont have a tuning machine present, is grab yourself a piece of cardboard or newspaper.
Then turn on your bike, hold the paper or card board about 3 - 5 cm away from the exhaust, can even squeeze the throttle a couple of times to get a few squirts and see what soot is building up on the paper. You can smell and feel the soot, and rub it through the fingers and see what colour residue its leaving. If its no colour then its fuel, if its a black'ish colour then its oil.

Hope this helps a little. But generally carb engines will often 90% of the time will always have low fuel efficiency and smoke blow out of the exhaust, thats just the nature of it. Hence the reason why society/governments are producing engines with EFI and catalytic convertors to boost fuel efficiency plus low emissions.

Cheers,
 

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I will try the cardboard test today as well as get a compression checking tool. One other thing, I put in 40 weight instead of 50 weight oil when I did the oil change. Would this lighter oil cause low RPM oil burning
 

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I will try the cardboard test today as well as get a compression checking tool. One other thing, I put in 40 weight instead of 50 weight oil when I did the oil change. Would this lighter oil cause low RPM oil burning
The rings on the pistons may be stuck from sitting for 6 yrs and that might account for the black soot/smoke. As for the oil, 10w-40 should be what you are running in the engine. you could try putting a little marvel mystery oil into the cylinders thru the plug holes. replace the plugs, turn the engine over without starting to let the oil get to the rings and let it sit a bit to help loosen the rings if they are stuck. Just a possible solution..
 

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I have pipes, air and jets on mine. I wonder if whomever redid the carb on yours used jets that are simply too big. What lots of guys are unaware of is that different jet manufacturers use different numbers, so the same number jet in a Keihin, Dynojet and Mikuni will all be different sizes. A stock 1500 Classic usually has a 138 Keihin main and a 42 pilot jet in it. I bumped my main up to a 142 Dynojet, which is a 155 equivalent Keihin, which is a pretty serious bump. I went with a 45 pilot jet. Now I get decent mileage (38-42 MPG ) and it runs good all through the throttle range. I have heard lots of guys say they went to a 170 main and for the life of me, I can't figure out 1) which manufacturer they mean, and 2) why a jet that big would ever be necessary. I tried a Dynojet 150 main and the carb dumped so much fuel into the intake it bogged down at both acceleration and constant cruising speed. And it got about 28 miles to the gallon.

Here's that conversion chart. Hope this helps. http://www.vulcanforums.com/forums/attachment.php?attachmentid=211945&d=1519756049

One thing though it that I'd try one fix at a time, whether it's oil or carb jets or whatever, so that you avoid a lot of tail chasing and when it is fixed, you'll know what the problem was.
 
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