My Honda Shadow VT 600 has been running rich since the day I bought it off Facebook Marketplace.
The previous owner installed pipes, a velocity stack, coils, and plugs. He also kindly supplied me with the rest of the materials needed for tuning because he had not done so already (jets, shims, etc.).
Since then, I have reverted all internals of the carb to stock due to a constant rich condition (which doesn't make sense due to the velocity stack and open exhaust). Even after doing this, the rear plugs are dark and sooty, while the front plugs are not as black, yet still much darker than they should be considering the current setup.
I replaced the leaky petcock and completly deep cleaned the carb, which helped but still didn't solve my issue.
I am new to working on bikes, so my question is: where should I go next? Electrical? Vacuum lines?
Yes, I have read the tuning guide lol.
Please Help!
Have you adjusted the air/fuel screw on the carb? Mine is a pain to do, but it may fix your issue
@chaz @chaz what year? singel or dual carb?> If this is a ’99–’07 single-carb bike, I would not keep chasing main/pilot jet sizes yet. One carb feeds both cylinders, so if the rear is dramatically darker than the front, something cylinder-specific is likely happening
Check the rear-cylinder ignition system. A weak spark can leave a plug black and sooty and look exactly like excessive fuel. The VT600 has separate ignition circuits/coils for the front and rear cylinder pairs, so the aftermarket coils/plugs the previous owner installed immediately getsmy attention. even new coils can be total ass and he may not have installed them correctly. Check plug type/gap, caps, wires, coil connections and grounds. If practical, swap known-good components front-to-rear and see whether the problem follows them
Have you deleted the AFP? theres 2 videos on my youtube channel that show you how to do it. its a recalled part. this must be removed before you do anything else.
Verify actual float level and float-valve sealing, rather than assuming a clean carb means the fuel level is correct. Honda specifically calls out a worn/contaminated float valve or seat as a cause of carb flooding in troubleshooting sections.
after all that -do compression and valve-clearance check. If the rear cylinder has shit compression or a valve issue, it can fail to burn the mixture completely and leave you with a black plug even though the carburetor isn't actually delivering an excessively rich mixture.
the PO's coils are suspicious to me
RikyTikyTavvy New Member
TJ Admin Staff memberModeratorMember who has the rights to delete posts, and ban members form forum if they violate the rules.