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Right this has me baffled... will give as much detail as possible as im struggling to find the problem.
1991 UK spec GSX750F runs but keeps dropping a cylinder at lower rpm (-4500) as the bike had a few faults (idiot lights earth had failed engine had a oil leak and the bike kept running rough) i decided to take it off the road for a short while so i could address the faults properly.
Over the last two weeks its had...
Engine
Cylinder head had to come off to replace the rusted through oil drain pipe as it was leaking quite badly.
cylinder head was cleaned and fitted with new gasket.
Valve clearances re-done set in the middle of the tolerance.
Carbs
Were fully stripped ultrasonically cleaned blasted out with a high pressure airline and rebuilt.
Jets are clean.
New fuel lines fitted
All orings and seals are present and correct in good condition.
The floats are all set at 14.6 and as far as i can tell seal correctly.
(inverted them blew through lines and could not pass air filled with fuel and again could not blow through them)
A/F screws at 2.5 out from completely screwed in .
Slides are moving freely.
Butterfly's all working correctly
Breathers are clear
Synced with vac gauge set all drawing an identical vacuum reading .
Electrics
All wiring has been checked any faults corrected earths were improved and whole loom was re wrapped with self amalgamating tape then loom tape for a hard wearing finish.
Extra info
Bike has coil relay mod & motobatt AGM high capacity battery and makes a healthy 11.9 while cranking.
Fuel tank was fully resealed with a POR-15 kit
After i rebuilt it i synced the carbs at the bikes riding temp , all was great revving fine ect.
Went for a nice 100 mile blast around the UK lake district (beautiful place to ride) and it ran amazing.
Rode home and parked up for the night, next morning i came out and started the bike with 50% choke fine let it tick over a few mins while i put on kit and rode to petrol station as i was down to a little over a third of a tank full.
Refilled tank and rode off, almost immediately the bike started dropping a cylinder at lower RPM and bogging down almost like it was flooding ?
Thinking maybe the weight of fuel in the tank might be causing some issue i drained the tank back to half full ....still bogging at low rpm.
I am completely at my wits end with it.....given that i have spent easily 50 hours over the last month trying to sort this stupid issue out i am seriously running out of patience with the damned machine.
HELP ?
1991 UK spec GSX750F runs but keeps dropping a cylinder at lower rpm (-4500) as the bike had a few faults (idiot lights earth had failed engine had a oil leak and the bike kept running rough) i decided to take it off the road for a short while so i could address the faults properly.
Over the last two weeks its had...
Engine
Cylinder head had to come off to replace the rusted through oil drain pipe as it was leaking quite badly.
cylinder head was cleaned and fitted with new gasket.
Valve clearances re-done set in the middle of the tolerance.
Carbs
Were fully stripped ultrasonically cleaned blasted out with a high pressure airline and rebuilt.
Jets are clean.
New fuel lines fitted
All orings and seals are present and correct in good condition.
The floats are all set at 14.6 and as far as i can tell seal correctly.
(inverted them blew through lines and could not pass air filled with fuel and again could not blow through them)
A/F screws at 2.5 out from completely screwed in .
Slides are moving freely.
Butterfly's all working correctly
Breathers are clear
Synced with vac gauge set all drawing an identical vacuum reading .
Electrics
All wiring has been checked any faults corrected earths were improved and whole loom was re wrapped with self amalgamating tape then loom tape for a hard wearing finish.
Extra info
Bike has coil relay mod & motobatt AGM high capacity battery and makes a healthy 11.9 while cranking.
Fuel tank was fully resealed with a POR-15 kit
After i rebuilt it i synced the carbs at the bikes riding temp , all was great revving fine ect.
Went for a nice 100 mile blast around the UK lake district (beautiful place to ride) and it ran amazing.
Rode home and parked up for the night, next morning i came out and started the bike with 50% choke fine let it tick over a few mins while i put on kit and rode to petrol station as i was down to a little over a third of a tank full.
Refilled tank and rode off, almost immediately the bike started dropping a cylinder at lower RPM and bogging down almost like it was flooding ?
Thinking maybe the weight of fuel in the tank might be causing some issue i drained the tank back to half full ....still bogging at low rpm.
I am completely at my wits end with it.....given that i have spent easily 50 hours over the last month trying to sort this stupid issue out i am seriously running out of patience with the damned machine.
HELP ?
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