Thread: Kind Of Missfire...
09-19-2008, 01:15 PM #1
Kind Of Missfire...
Hay guys '02 GP1200r Riva STII with extras
Kinda got a missgfire problem. #1 cyl.spark plug is cooler to the touch that 2 & 3.
Basicall end of WOT run did 180 turn letting off the gas a little and BLLAAAAA down on power. Got back to the ramp and on the trailer and black goo was dripping out of the exhaust - back of ski looked nasty.
Anyway checked compression even stripped # 1 after noticing cyl was cooler, checked carbs and fitted new valves and seats, checked pop-off and leak-down etc, new plugs and NGK racing wires and sparks look ok on all cyls.
So now I'm thinking CDI or flywheel since they the only two two things left that soley can affect #1 . Have also checked and cleaned / sealed all connections around the black box and gauges.
Oh yet this ski has 373 hrs on it !
09-19-2008, 01:26 PM #2
Sorry guys the tying in that message is bad !!
But thats the 4th time Ive typed it - since it kicked me out 3 times
I think its understandable ???
09-19-2008, 01:31 PM #3
09-19-2008, 01:47 PM #4
140 ish accross all 3. took down the cylinder(everything good), inspected reeds etc, new headgasket .
09-19-2008, 01:48 PM #5
PS. ski has 372hrs on it - motor has 6 hrs on it
09-19-2008, 01:52 PM #6
- Join Date
- Aug 2006
Since you said spark looks good, alot of times if you are missfiring a bit, you will feel it, as well as get backfires from the extra unburned fuel loading up in the exhaust. Widen the gap on the test plug that you are looking at when testing the spark to be sure the COIL isn't breaking down on a bigger load.
If not, I would tend to still think fuel, or perhaps the reeds. You said you did a leakdown, you mean an air leak test of the complete engine? Cause a big front seal leak might make it lean enough to not run on that cyl.
09-19-2008, 01:56 PM #7
- Join Date
- Aug 2006
You were replying when I was writing my first comments. Check that COIL, that is what the CDI fires. In the manual it tells you how to check it as well as the stator and CDI without taking engine apart.
09-19-2008, 02:46 PM #8
I went into the electric box and swapped coils (problem stays with #1) . Checked reeds. Changed fuel. Leakdown is also good. Lots of fuel hence the black goo dripping out of the exhaust and plus is wet.
IMHO I dont have much faith in the factory tests with a DMM - its not a real world test, the operating conditions are way different. I.e. load, heat vibration etc You just cannot replicate those. And I have in the past had good tests with a DMM but changed out the component anyway and it fixed the problem.
I dont think its the stator as ther is only one pickup for all 3 cyls and 2 & 3 are strong. Flywheel is a possiblity - 3 magnets ?!?!?
Last edited by BahamasGPR; 09-19-2008 at 02:48 PM. Reason: More info
09-20-2008, 09:06 AM #9
09-20-2008, 09:17 AM #10
Could be crank indexing or other problem, or flywheel not many choices left.
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