My 98 lowrider had a idle problem that I can't seem to figure out. It has a mikuni hsr42, 20 pilot and 165 main, about 1 1/2 turns out on the air screw. I had replaced the intake manifold with a new stock one, with new seals and flanges, and the rubber ring that holds the carb is also new. I have checked several times spraying wd40 around the manifold and I'm sure there is no leaks. I average around 40 mpg. It runs and pulls good and gets down the highway good too. I've checked the throttle cable, I only have the pull open cable, and it has a tiny bit of slack in it, the choke cable has a bit of slack as well. The problem is when I been riding a while and come to a stop it will idle fine, I take off and ride more, stop again and it will be idling high. It seems it idles at a different speed every time I stop. This fluctuation goes between 900 and 1100 rpm. I'm always reaching down and pushing the choke in to make sure its not on. I've replaced the fuel line and valve with a pingel valve, the vacuum line to the voes is new too. The inside of my gas tank is clean. The carb is new and been on about 3 months. I've recently replaced the cam sensor and set the static timing according to the the factory manual, I put a timng light on it using the clear timing plug and had a hard time seeing the marks so I left it as it was. It starts easy hot or cold and I get no back firing or popping. I'm currently running drag pipes with torque cones and read many debates on that, but it just runs and sound great with them. This idle problem is driving me crazy! Could it be timing or another source for a vacuum leak I'm overlooking? I'm really thinking of getting rid of the mikuni and going with a S&S super E carb and manifold, Thought I would see what advice the Harley guru's could give first, always getting good info here. I bought the bike used and the previous owner believes it to be all stock, it has 38,000 miles on it. I'm looking foward to any advice you guys could offer on this issue. Thanks guys....Long Live Evo!!!

 

You need to check your VOES with an ohm meter. Pins 6 and 7 in your harness start the bike let it idle and rev etc. watch the meter it should zero out. If you don't get s zero reading it's bad. I had this issue and I couldn't get my idle right it was my VOES unit. It's way easier to test if you can just suck on the VOES hose and leave the bike off but not sure if you can reach it. VOES directly impacts your idle.

As far as your timing, if you want to check that you need to mark the timing marks with bright paint. I did mine with fluorescent orange and you can still barely see them. You should use the 2 dots at 1050-1400 RPMs