suicide bobb
XS400 Member
Alright. My mechanic said the valves are to factory spec, but I can't say he's been especially trustworthy up to this point.
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XS400 Seca, running very slow and poor throttle response
- Thread starter suicide bobb
- Start date
Alright. My mechanic said the valves are to factory spec, but I can't say he's been especially trustworthy up to this point.
It's fairly easy to do. Put bike on Center stand. Remove seat and gas tank. Disconnect tach cable. Remove spark plugs. Remove access cover on alternator. Remove upper engine mounts. Remove wiring harness guide. Remove cam cover. Measure valve clearances and take notes. Make sure clearances are at or above minimum in manual, with the engine at ambient temp. Place valve cover back in place. Calculate new shim requirements and get shims from Yamaha or Kawasaki dealer 29mm diameter). Rotate engine until desired valve is open. Insert thick nylon wire tie (zip tie) through spark plug hole between valve and seat to hold valve open. Rotate engine until cam lobe is pointing away from valve. Chance valve shim. Rotate engine to remove wire tie. Repeat for remaining valves.
The first time should take you about 2 hours of actual working time. Plus the time to get the shims. Every time after should be about 1 hour working time.
The first time should take you about 2 hours of actual working time. Plus the time to get the shims. Every time after should be about 1 hour working time.
If you carb is full of rust it will
A back fire through the carbs could also be a timing issue or a bad valve seat.suicide bobb
XS400 Member
Keep in mind guys, this issue pops up suddenly after the bike warms up. It clicks in like a switch. Doesn't just slowly show up, it hits like a hammer
bob, your symptoms are those of one cylinder dropping out. This happens when there isn't enough fuel delivered, and especially at high rpms you are sucking a lot of fuel. The mixture also leans out when the bike gets hot, my guess is that that triggers the dropping out. Sounds like carbs.
these guys know their stuff
these guys know their stuff
suicide bobb
XS400 Member
bob, your symptoms are those of one cylinder dropping out. This happens when there isn't enough fuel delivered, and especially at high rpms you are sucking a lot of fuel. The mixture also leans out when the bike gets hot, my guess is that that triggers the dropping out. Sounds like carbs.
these guys know their stuff
Yeah, it definitely feels like one cylinder dropping out! I think I'll do another carb deep clean and see what happens.
