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Join Date: Nov 2007
Location: Chandler, Arizona
I have gravity bled the brakes on every one of the 50+ bikes I've owned. You just loosen the bleeder screw(s), remove the master cylinder cover, don't touch the brake lever, and let it dribble. Stay next to the bike. Pull up a chair and open up a beer if necessary. It may take a while. All you have to do is make sure the master cylinder reservoir does not run empty and let air into the system. If it does, you will have to start all over again. I flush out and refill the fluid on all 6 of my bikes every couple of years. Never had a problem doing it that way.
As far as the rest of it, is the bike stock, meaning does it have the complete stock intake and exhaust system on it? If not, you're on your own. There are an infinite number of variables. It will all be trial and error. IF it is one of the few that is still stock, then the stock carb jets and pilot air screw settings should work, although removing the EPA plugs and turning the pilot air screws out a bit will definitely help. You said carb, there are TWO carbs, which share a common float chamber assembly. It is a very unusual design. There are several places where it is not difficult to make a mistake when reassembling them. Besides the main diaphragms, there are 2 more diaphragms, one on the side of each carb. These control the coasting enrichener. The EPA set the mixture so lean on these carbs that it caused the engine to backfire on deceleration, requiring a complicated system to richen the mixture on deceleration. I found those coasting enrichener diaphragms MELTED on mine once, likely due to ethanol gas.
Also, there is at least one, maybe two systems that need to be removed is they are still on the bike. One is the PAIR system, which all VN750s have, and if you have a California model, there is also the evap system. Remove EVERYTHING, then cap/plug anything these EPA systems connected to. There is a lot of information on here explaining on how to get rid of this EPA garbage. Also take the gas cap apart, and remove everything inside. There is yet another diaphragm valve in there. The tank MUST be vented to the atmosphere to work properly.
Spark plugs are not calibrated, they are gapped. They need to be gapped properly, and they need to be CLEAN. The VN750 has a weak ignition system, and it doesn't work well, if at all, with dirty plugs.
Unless you have a serious internal engine problem, an engine knock sound is usually the result of defective cam chain tensioners (every VN750 cam chain tensioner ever made was defective as far as I can tell) and the cam chains are loose, or the counterbalancer dampers are deteriorated and the balancer is hitting the case. Either one can destroy the engine if not fixed pronto.
White smoke has nothing to do with running too rich. That would cause black smoke and a strong exhaust smell. White smoke is either oil burning, or steam escaping from the cooling system. If you have steam from the cooling system coming out the exhaust, you have an internal coolant leak from somewhere. Look at the oil sight glass. If you just changed the oil, all you should see is clean oil. If it looks white or milky, you may have coolant in the oil, or it could just be from condensation forming inside the engine, and will quickly burn off.
What was your reason for replacing the thermostat?
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike