So finally got some time to put a few miles on my bike and I am noticing an almost hesitation, or a flat spot right around 2000-2400rpm when I am "cruising" or holding a steady speed. Bike will kind of lurch. I put a v-thunder 3020 cam in it. I put then 30 miles on bike before I put cam in it, and I vaguely remember it doing it then. I have changed jets, Running 50 pilot, 180 main. and have screwed around with a/f screw and that doesn't seam to help. When I removed cam I marked the timing plate so its in same spot. I have yet to put a light on it. (Have to go buy one). checked for air leaks, didn't seem to have any.

Wondering if this is a typical sign of timing being off or possibly float/needle needing to be adjusted?

Thanks!

 

My guess is carb adjustments. Check spark plug color. Put a timing light on it cause most mechanics only static time.... Use to live in sw minn, ever heard of 1/4 mi. Racing Tom Hoover?

 

At the rpms's mentioned you are on the needle, 50 is a little fat for that set up but not in the low jets range when the problem is present, you may try raising the needle to fix it

 

I did the same when installing my cam and later found the timing off. I set the timing by the manual and improved the performance. Later I installed a Dyna 2000i ignition module and found I was still a little off on the timing. My bike has never ran or started better. The mpg also increased by 6-mpg.

 

you said it did it before you installed the cam, mine did that too. I found the vaccum slide on the carb drilled out to large, I jb welded it back up and redrilled to 7/64. that took care of the surging for me. Something to check????

 

I have the 3020 cam in mine, and my CV is setup with a 46 slow jet/180 main jet/CVP velocity needle/CVP emulsion tube. Bike runs well with this setup.
You should be able to make the bike stumble/shudder/shut down when you lean out the idle mixture screw, if it doesnt your slow jet is definitely too big.

 

Well what I am going to try today since its raining out is move needle up one spot and replace intake manifold seals. didnt appear to be leaking but just to be sure. I had a 48 pilot jet in, and i was still getting a "Cough" that's why i went to 50. I am not getting a stumble when i screw a/f in with 50. might try and go back to 48 and screw around a little more with screw.

 

Replaced intake manifold Seals. Allen Screws were finger tight and seals were dry rotted! Hoping replacing them helps. Also Put 48 pilot back in and moved needle one clip up. Had a red needle in there? never seen a colored needle on my other stock cv carbs so i am assuming previous owner has some sort of aftermarket needle in it.

Too cold to test drive. 45 Degree's and pouring rain. Damn Lake Superior!

 

You most likely fixed it with the seals, I know Yost uses a red needle but can't say that is what you have and aftermarket emulsion tubes have more holes in them and a way to tell if it has been changed.

Fuel mileage and plug reading will tell you if the needle height is correct now if it runs ok, you will be on the needle most of your riding time

 

Usually they have less holes, as few as one per side.