HI, any help would be great. I have a 05 FXDWG with stock pipes that were punched out and a K&N Air filter, My bike runs like a top but pops out the carb. and will stall when started. I was told to just give it a little throtle and set the screw on the grip, that does not fix my problem. I think I need to rejet I just don't know what size to use ? Thanks of any help.

 

I assume you are running a CV carb?
Not familiar with that carb. For the most part there is a certain amount of info I can give you that holds true for nearly all motors.
1) you increased intake and exhaust flow so now you need to increase the full supply to match. You will likely need to increase both the pilot and main jet circuits. Pilot is idle to about half throttle, main is about half to full throttle. Some carbs have a mid range circuit, some have thunder jets for upper and use main for intermediate, some carbs have air bleeds to fine tune the transition from jet ranges.
2) when you do make changes to the jetting of the carb, only make one change at a time. Do not try to switch both pilot and main jets as it is to hard to distinguish which adjustment gave you which result. When I am trying to jet a carb I keep a journal of what change I made, what the temperature was, how humid it was and then make note of how the bike ran. I can always look back to my notes later and not have to rely on my memory.
3) if you so have a cv carb, you can get jets for that from most Yamaha dealerships as they use keihin bd carbs on a bunch of their things and those have the same jets as almost all other keihin carbs.
4) as far as what size jets you need to use, first you need to know for sure,what carb you have, then someone might be able to help. Would also be helpful to know which jets you are using right now.
Good luck to you!

 

Not sure what "stock pipes that were punched out" means. Did you just get this bike, meaning you don't know what, if any, mods were done. How many miles? The previous owner may have "f'ed -up" the pipes which could be the source of your problem. Get a service manual if you're going to be wrenching on your bike.First, reverse what u did with the throttle cable and setting the screw on the grip.Use a dental mirror available at Ace hardware and look at the bottom of the carb to see if the a/f mix screw is visible, or just take your intake and carb off instead. If you can't see it, the plug is still in there and needs to be adjusted, on the richer side. You'll havta take the carb off and drill the plug out CAREFULLY. Generally, you turn the screw in till lightly seated, then back it out 2 1/2 turns and fine tune from there. If you take the carb off, check jet sizes which in a stock bike should be a 45 and 185 main, 190 at the most depending on altitude and temperature. Clean the carb while it's off and you may as well check the float adjustment. Again, you need a service manual. Other things to check for, before removing the carb and replacing jets - search on the forum for how to check for intake and exhaust leaks. If all the above check out OK, report back and you'll get a new list of things to check.

 

The carb is jetted to lean. Follow RKH's advice and start with the A/F adjustor, that't the idle circuit but that circuit is also pulling some fuel from the pilot jet. You can start with 2.5 turns but you have to give the engine what it wants. If you turn the A/F screw all the way in the engine should stumble and/or die. If it dies, like turning off the ignition, you need to go up on the pilot jet. Work with the idle ciruit until you have found the " sweet" spot where the engine is idling the smoothest. The engine has to be at operating temps for this adjustment. CV Performance makes an A/F screw that you can turn with your fingers; no screwdriver required (PITA).

http://www.cv-performance.com/carburetor-parts/

Once you get that worked out, ride the bike and pay attention to throttle position and rpms where the problem occurs. If popping on decel, the A/F screw is too lean, back it out about a 1/4 turn at time until the popping goes away. You probably will need to go up on the main but I would start with raising the needle with some brass washers that are .025" thick; try one and that improves, try another; shouldn't take more than two.

Carb tuning is tedious and you have to make incremental changes starting with the idle circuit, mid range and WOT; get one right before moving to the next. Check the link for a good read on carb tuning and the chart to show where the various parts of the carb affect performance.

http://www.nightrider.com/biketech/hd_cv_mods.htm



Patience is the key; good luck!