Took the Straight Shots off my '05 1200c and bike runs rough now. Should I put stock jets back in? Don't know what are in there now.

 

Did you do a jet change previously? I'll continue as if it was like that when you got it.

What did you put back on, stock or aftermarket mufflers? If it ran good with the Straight Shots, it must have a size larger low speed jet in the carb. A high speed jet change is seldom needed, unless you like running near redline a lot.

Have you checked the bottom of the carb (might need a small mirror) to see if the mixture screw plug has been removed? You can adjust the mixture screw for smooth running with both stock or most aftermarket mufflers with a size larger low speed jet.

Aftermarket pipes with stock (very lean) low speed jets often stumble and backfire at low rpm and sometimes when backing off the throttle. The decrease in back pressure with low restriction pipes leans out the carb mixture, and from the factory, they're about as lean as they can run smoothly. There are more complicated ways to set up the carb for ideal performance, but a simple size up low speed jet and mixture screw tweak will do well enough most folks probably wouldn't notice the difference.

 

I'm assuming the former owner who put the straight shots on re-jetted, so want to be sure I have stock jets, since I put the stock pipes back on. Bike vibrates excessively and I've replace the motor mounts. Should I just replace the main jet?

 

If it ran decent with those pipes on, he probably at least went up a size on the low speed (pilot) jet. Have you looked under the carb to see if the mixture screw head is exposed? That would indicate something was done and the mixture was adjusted to compensate. If the plug is still in, and a jet was changed, it's probably way off.

If it's not backfiring or stumbling at low rpm, I doubt the carb is causing vibration. Is it a steady vibration that changes with rpm, or irregular, with changes in throttle? Does it vibrate the same sitting still, or steadily increase with speed? Excessive vibration is usually something mechanical, possibly ignition related but not fuel related. You could check the plugs; if the carb had been set up wrong, the plugs may be fouling and misfiring, but I think you'd be able to tell the difference between misfiring and mechanical vibration.

A jet change is fairly simple. The sizes are stamped on the jet, so you could match what you have in there against stock numbers. I'd recommend against going with other than stock for the main jet, but stock or even a size up on the pilot jet should adjust out just fine with the mixture screw using stock mufflers. You should get a bit more power in the mid rpm range with stock mufflers, too, wide open pipes are best for high rpm, not where you spend most of your time with a Harley, unless you do a lot of other work on it besides the pipes; in near stock configuration, they run better with some back pressure in the pipes.

Here's a page that has some good info:

http://www.harley-performance.com/ha...r-jetting.html

 

Thanks for the info. Imold too. Pulled the plugs and they are white, so it's running lean. Vib is at all speeds, vitually shuddering, like it's running on one cylinder. So threw a new set of plugs in and I'll fire it up tomorrow and see how it runs.