One of my other bikes is a ‘94 Suzuki RF900R, I am baffled by a running issue and thought would reach out here.
Bike has about 12k miles and went through and changed all fluids, plugs, etc last spring. Put about 350 miles on it and put it up for winter. This winter I added a 4 degree advancer for mid range performance and was bolt on modification swapping out original. Went to start bike and felt like was missing on one cylinder. Suspecting carbs pulled them and cleaned. Found some small things but nothing major and reinstalled. Had same issue, bike starts fine, idled and then would start acting like missing cylinder. Checked spark all plugs and good. Ignition coils tested fine. Pulled carb again and found similar issues. Note that I am using remote fuel tank with fresh gas. Putting air box back in found pre filter was completely rotted and as soon as you touched it turned into crumbles. Problem solved! Replaced filter, got bike running and same issue
Pulled carbs, cleaned, started poling around and see one of the valves in one cylinder had carbon on it. Put camera down and see carbon on top, while rotating engine over, noticed there were bubbles coming off that valve
. Never seen anything like this before! Sprayed WD 40 in there and tried to carefully clean some off without any luck. Did confirm valve seats and holds wd40. Upon both strokes as air enters you can see where bubbles form around valve seat.
I put original advancer back in, rebuilt carbs, and ordered new plugs and plug caps to rule any fuel/electrical issues. Thoughts on what might be happening with this valve? Cause for concern or fire it up and hope new parts fixes things?
Valve stem with carbon build up:
Valve when going through strokes creates some bubbling action, this was prior to WD40:
Bike has about 12k miles and went through and changed all fluids, plugs, etc last spring. Put about 350 miles on it and put it up for winter. This winter I added a 4 degree advancer for mid range performance and was bolt on modification swapping out original. Went to start bike and felt like was missing on one cylinder. Suspecting carbs pulled them and cleaned. Found some small things but nothing major and reinstalled. Had same issue, bike starts fine, idled and then would start acting like missing cylinder. Checked spark all plugs and good. Ignition coils tested fine. Pulled carb again and found similar issues. Note that I am using remote fuel tank with fresh gas. Putting air box back in found pre filter was completely rotted and as soon as you touched it turned into crumbles. Problem solved! Replaced filter, got bike running and same issue
Pulled carbs, cleaned, started poling around and see one of the valves in one cylinder had carbon on it. Put camera down and see carbon on top, while rotating engine over, noticed there were bubbles coming off that valve
. Never seen anything like this before! Sprayed WD 40 in there and tried to carefully clean some off without any luck. Did confirm valve seats and holds wd40. Upon both strokes as air enters you can see where bubbles form around valve seat. I put original advancer back in, rebuilt carbs, and ordered new plugs and plug caps to rule any fuel/electrical issues. Thoughts on what might be happening with this valve? Cause for concern or fire it up and hope new parts fixes things?
Valve stem with carbon build up:
Valve when going through strokes creates some bubbling action, this was prior to WD40:
