Jetting Question

[6685]

I have a 77 cb750k with K&N Pods and Carpy's 4 into 1 exhaust.  I changed the main jets from stock 115s to 130s.  The carbs are in sync, clean, and the intakes have no cracks.  She idles fine and pulls away good, but when I acclerate hard on the throttle she starts to sputter. Do you think I need bigger main jets?
Also, when I gas the throttle it takes awhile for it to return to idle.  The throttle seems to stick and hang at the higher idle.  New throttle cables are on the bike.  I am totally lost with this.  Please help.  Thanks.

[vern401]

Hanging/lagging rpm is usualy due to the carbs not being synced right or the floats are not all set the same.
Make sure all your slides are going back down and the needles are all at the same setting.
Anothe possible problem is a vacuume leak. use carb cleaner or WD-40 and spray any connection that goes to the carbs or intake to ensure it is not leaking.
Check the timming it can also cause those symptoms.

[Re-run]

What color are your spark plugs? Have you made any other change other than the exhaust? Do you have pods or the stock air filter? Any mods to the bike? If All you have done is teh exhaust, your mains are going to be way too big. Many times people have 130s when they have done engine work along with mufflers and intake.

Also, most likely, this issue is going to deal with the idle circuit anyways. A carb sync of low float height could certainly cause this but a very common issue is that the idle mix screw needs to be adjusted. Get your plugs clean and then, with the bike warm, idle it at about 3000 rpms for a couple minutes. Direct a fan at the engine to keep air flowing over it.
Check your plugs then and see what color they are. if they are very white or virtually clean, then they mix is too rich and the screws need to be turned out 1/8th turn and check again.

If you have a shop tach or a dwell/tach, get everything synced very good and then start on #1 and adjust the mix screw to max rpm and then back off about 100 rpm. You should do this at 1000 or so rpm.
Go through each carb doing this. At that time, you should have a good mix.