Misfire below 7k rpm
Posted: Sat Sep 08, 2018 11:04 am
All,
Having got my sons 1993 GSXR 400 SP running beautifully, I'm now trying to get his 1992 GSXR 400 running beautifully too!
I have:
Pulled carbs
Cleaned thoroughly
Replaced O-rings on mains, air screw, fuel feed (orange tree thingy)
Pulled slides - checked condition
Replaced 117.5mm mains with 100 mains (its an ex-track/race bike)
Checked pilots - 47.5
Reset needle clips to middle position
Went out for a run, after 5 miles, started to misfire between 2k rpm and 7k rpm, then it runs clean right into the red. Absolutely howls as it has a (too loud) race can.
Rode home. Left it 30 minutes. Started it up and went for a potter - ran clean from 2k to red line - no misfire.
Came back, left it an hour, went out for a proper run. Started to misfire between 2k and 7k rpm again.
Came back, pulled plugs. 1 and 4 sooty black, 2 and 3 normal. Suspect Low Tension side of coil failed.
Bought second hand genuine GSXR 400 coil. Fitted.
Started it up this morning - misfired between 2k rpm and 7k rpm from cold.
Any ideas? I do wonder whether there is an issue from air screw to pilot coming onto the main, hence it howls above 7k rpm.
Or maybe plugs are knackered? Going to fit a new set.
Its just such a pain in the backside pulling the carbs again. Wonder whether one pilot is blocked/crap is still circulating (the carbs were foul inside).
I had thought electrical because on cooling down it worked, and then misfired again after 3 miles. But it is mechanical - carbs?
I'm not prepared to pull parts of the 1993 model to test on the 1992. That's running so well I dare not touch it!
Thanks
Having got my sons 1993 GSXR 400 SP running beautifully, I'm now trying to get his 1992 GSXR 400 running beautifully too!
I have:
Pulled carbs
Cleaned thoroughly
Replaced O-rings on mains, air screw, fuel feed (orange tree thingy)
Pulled slides - checked condition
Replaced 117.5mm mains with 100 mains (its an ex-track/race bike)
Checked pilots - 47.5
Reset needle clips to middle position
Went out for a run, after 5 miles, started to misfire between 2k rpm and 7k rpm, then it runs clean right into the red. Absolutely howls as it has a (too loud) race can.
Rode home. Left it 30 minutes. Started it up and went for a potter - ran clean from 2k to red line - no misfire.
Came back, left it an hour, went out for a proper run. Started to misfire between 2k and 7k rpm again.
Came back, pulled plugs. 1 and 4 sooty black, 2 and 3 normal. Suspect Low Tension side of coil failed.
Bought second hand genuine GSXR 400 coil. Fitted.
Started it up this morning - misfired between 2k rpm and 7k rpm from cold.
Any ideas? I do wonder whether there is an issue from air screw to pilot coming onto the main, hence it howls above 7k rpm.
Or maybe plugs are knackered? Going to fit a new set.
Its just such a pain in the backside pulling the carbs again. Wonder whether one pilot is blocked/crap is still circulating (the carbs were foul inside).
I had thought electrical because on cooling down it worked, and then misfired again after 3 miles. But it is mechanical - carbs?
I'm not prepared to pull parts of the 1993 model to test on the 1992. That's running so well I dare not touch it!
Thanks