Hey guys I need a little help. I recently put my cobra shotguns back on my bike and I've noticed a decrease in MPG. I'm running a Barons ported manifold, AIS removed, RC-1980 K&N filter, barons needle on 4th clip, #170 main, #37.5 pilot, and 2.5 out on PMS. Primarily highway riding. I've also noticed lately that while sitting at a light I I blip the throttle, occasionally the bike will cough and almost die. It's definitely coming from the carb just not sure exactly what would cause that. Does it primarily when its hot. I'm
I'm Not sure where to go from here. Any and all help would be great

My first thought is that it's a lean condition, but since your mileage is down and you say it's worse when hot, it could be a little fat. Usually if it's too lean, the motor won't run right until it's good and hot. A lean condition can also show up as surging at steady cruising speed and it can be boggy when opening the throttle quickly. If it's too fat, it will run better cold than hot, and be slow to RPM from idle and might load up and blubber a bit.

First thing to determine is which condition it is. What color are your plugs?

You might see about adjusting this a bit...(accelerator duration screw in the article)
http://roadstarclinic.com/content/view/63/96/

I have the lock nut on top of the arm, and the screw about 2 1/2 turns off the lock nut. You may be getting to much of a slug of fuel, this should help with that.

Also, when it's hot, check your idle, and if it is low, turn it up to about 900rpms. You might double check the idle first. Once you set it when the motor is hot, leave it alone, unless it's hot, and you want to double check.

Make sure the enricher is shutting off all the way also. You can slice little thin donuts off the back of it until you can slip a piece of paper between the back side of the knob, and the rubber bumper it stops against.

If the weather is colder now where you are, and your doing more cold starts, and leaving the enricher on longer before shutting it off, that will hurt your mileage also.

Check your air cleaner, if it hasn't been cleaned in awhile.

Whens the last time you changed the plugs?

Have I missed anything????

Air cleaner is 2 months old. Plugs are 2 weeks old. It only coughs about 1 out of 25 times I blip the throttle. It's very sporadic How would I check the idle without a tach? I'm in central fl so it's not cold lol

Listen to the vid in this thread, and ignore the texas wind.

http://roadstarclinic.com/component/option,com_fireboard/Itemid,187/func,view/catid,49/id,560238/

Check all your vacuum lines also. You could have a vacuum leak that only shows up when hot.
Maybe you disturbed one when changing pipes?

Salem wrote:
Check all your vacuum lines also. You could have a vacuum leak that only shows up when hot.
Maybe you disturbed one when changing pipes?



.....and revisit the torque on your flange nuts for the exhaust. Not uncommon for them to loosen a little as everything settles back in.