Carburetor Tuning Advice, 2001 sv650

So I am new to the forum and have had my 2001 sv650 for 3 years now. I installed the Vance & Hines S4 exhaust 2 years ago. At that time, I rejetted the carbs with 152.5 mains, 17.5 pilots, installed 2 shims on the needle, performed the snorkelectomy to the factory air cleaner and backed out the air/fuel screws 2.5 turns. After doing all that, she ran like a dream. The front wheel popped off the ground in first and second gear with just a crack of the wrist.

I started her up this spring and she ran great as well. Within the last month or so, she has started to surge around the 3k-5k mark and will hesitate--sometimes even backfire- on hard acceleration after the bike has been warmed up and the ambient temperature is above 80 degrees or so. I pulled out the plugs and they are white. I have also heard the cooling fan kick on a couple of times and I do not ever remember hearing it prior to this problem.

To try and remedy this problem, I have double and triple checked that the carbs are clean, checked all vacuum lines and carburetor connections for leaks, checked to make sure that the carbs are synced, added a third shim to the needle and that just made my eyes burn because it was running so rich that i removed it, changed spark plugs, and partially blocked my de-snorkled air filter with duct-once again it ran too rich.

Does anyone have any ideas? I am starting to run out of things to check and I really, really want to go out for a long weekend ride. Is it possibly time to check the valves, there is 11k miles on the clock? I am not sure if this is related, but it appears that oil is coming out of the oil catch canister that is connected to the air filter box.

If it helps, the bike is yellow!!

[Viney]

Originally Posted by muddy_cj5

If it helps, the bike is yellow!!

There you go, you answered it yourself!

Check that the carbs are pushed home into the rubber grommits. Find a standard airfilter and bung that in (See if that changes anything) Are the Diaphrams in the carbs ok? You could have a faulty plug, or coil?

Im just throwing ideas at ya. Im sure someone will be a long soon enough to give you a real answer!

isnt white plugs indicative of running too lean? that could be an air-leak

[yorkie_chris]

Check the valve clearances if you wish, but I doubt this is the cause. It does sound like you have some blockage. Depending what throttle it misses on it could be any circuit.
The other option is an inlet rubber, or an airbox drain piece has cracked.

Oil coming out of the catch can is normal, there will probably be a bit of slimy coating in the airbox.