I am close to putting a match to the damn thing. As above I have a misfire at any rev's on my CBR Fireblade 900 No1 cylinder. To date I have had the carbs apart checked all the jets, rubber diaphragms, butterfly's and rubber connecting sleeves for faults or air leaks, changed the coils for a spare set I had and fitted new plugs and carried out a compression test. There is nothing stopping it running on all four, fuel/air - compression - spark, but bit won't. Pull the HT leads off of No.2/3/4 and the engine slows pull the HT lead off No.1, no effect at all but there is a very good spark when held against and earth. Can it be another cause, but surely if it was a sensor or similar it would not run at all. Please help if you can, thank you.
Try swapping the plugs 1 and 2 around then pull the ht leads off whilst engine is running to eliminate #1plug ,,,,,,, if you haven't already tried
Tried swapping plugs and leads and pulling the HT leads off when its running, pulling off number one lead has no effect on the engine where as with the others the engine speed suffers, but strangely the header gets hot but I think it maybe heating up from the others. Ive got compression, fuel/air mix and spark, as mentioned I have changed the coils, HT leads, fitted new plugs and rebuilt the carbs. In desperation I think I may take the head off and have a look at the valves and pistons, reset valve clearances and if its still the same I might bin it and get a different engine off Ebay, there cheap enough now. Thanks for your suggestions they are very much appreciated.
At a guess fuel probably not getting to inlet chamber, good luck with it Let us know how you get on with it Barry
Have you tried it on the starter (with the ht leads pulled off all the plugs and the number 1 plug not fitted at all) with a tissue held over the plug opening for number 1? That’ll confirm if the petrols getting through - but be careful the engines cold etc you don’t want it going up in flames
