Fentible
XS400 Enthusiast
After exhausting all the possibilities regarding a misfire on my 1980 XS400SE (4G5) with regard to ignition and carbs. I am still left with a bike that stutters and misfires from around 4K revs and struggles to rev beyond when on the move. Still starts on the button and ticks over at exactly 12K revs without a stumble, revs on the stand and on the move pulls quite strongly until the 4K barrier.
The Right plug shows a perfect mixture while the left looks black and sooty. Decided to try a hotter plug today so went and bought a BP6ES, new plug in and 400 yards onto a straight I opened her up to the now annoying 4K stutter, took it about half a mile and with the new plug in, it did drive through the 4k barrier, also pulled better in the higher gears but still misfiring. Once back on the drive I took the new plug out to see what looked like wet oily deposits around the end and nose of the plug.
That got me thinking, wet oil on the plug would surely cause tracking and a misfire?? Source of the oil ingestion can only be damaged oil rings, worn valve guides or the valve stem oil seals aren't sealing. This bike had stood for 18 years prior to me getting it running and has an indicated 18K miles on the clocks.
Any thoughts from the collective??
The Right plug shows a perfect mixture while the left looks black and sooty. Decided to try a hotter plug today so went and bought a BP6ES, new plug in and 400 yards onto a straight I opened her up to the now annoying 4K stutter, took it about half a mile and with the new plug in, it did drive through the 4k barrier, also pulled better in the higher gears but still misfiring. Once back on the drive I took the new plug out to see what looked like wet oily deposits around the end and nose of the plug.
That got me thinking, wet oil on the plug would surely cause tracking and a misfire?? Source of the oil ingestion can only be damaged oil rings, worn valve guides or the valve stem oil seals aren't sealing. This bike had stood for 18 years prior to me getting it running and has an indicated 18K miles on the clocks.
Any thoughts from the collective??