slice Posted April 24, 2013 Posted April 24, 2013 Ok folks if you will do your best to think what this might be I would be obliged. Took the bike out yesterday ran well and had a lot of fun right up till it started to fart and misfire, checked the plugs (ok) checked fuel lines(ok) was stopped on the side of the road swearing at it and it would not start, then out of nowhere it fired right up but not firing on number 4 cylinder. is it possible for one side of the coil pack to break? Fiddled with the HT cable and found it had a spark but still would not fire so decided to ride it home anyway and sod the damage it might do, half a mile down the road it fired up and went like nothing was wrong, the only other thing I had done was turn the fuel tap to reserve!! Oh and when it first behaved badly I had just passed a little sports car at about 80 so was also wondering if coil pack can break down with heat/stress? Any thoughts on what might be the problem would be appreciated as I am stumped, by the way this is NOT the first time it has done this (misfired) but the first time it has actually ground to a halt, first time was on the M5 at a steady 75 for a couple of hours. Thanks all.
KirriePete Posted April 24, 2013 Posted April 24, 2013 Could just be the plug breaking down under pressure - you could try swapping plugs around to see if the problem moves. Or .... has Groucho been round your way lately?
Noise Posted April 24, 2013 Posted April 24, 2013 How many Carbs have you got on it? im just thinking that MAYBE where you was running low on fuel (not on reserve yet) possible that the carb feeding that cylinder got low and could not supply that pot with fuel...........until you turned the tap to reserve. just strange that you had a spark so the coil must have been working to provide the spark. But my other thought dose turn to Grouch
jimmy Posted April 24, 2013 Posted April 24, 2013 Swap the coils over and try it. I had an xs1100 and it developed a misfire, turns out there was a hairline crack in one of the coils which, when it heated up, expanded enough to cause the miss
slice Posted April 24, 2013 Author Posted April 24, 2013 Thanks lads, It has 4 carbs but just filled it with fuel so not a low fuel problem, new plugs this winter but always a possibility will try swapping them, I was thinking it might be a coil breaking down but it was still firing on the other 3 cylinders and I think it's not possible for only 1 bit of the coil to go bad, not sure about that tho. And NO GROUCH has not been round but maybe I have been cursed with his demon (must stop laughing at his antics), will have another look at it 2moro and see if any of your ideas has an effect. Thanks again.
Moderator Cynic Posted April 24, 2013 Moderator Posted April 24, 2013 Might be a bit of floaty gunk in the carb. Had it happen to me more than once. Everything fine then for whatever reason you give it some beans. The floaty bit moves and covers the jet. Then it either passes through or comes away when you stop and everything rosy again.
Tommy xs Posted April 24, 2013 Posted April 24, 2013 Might be a bit of floaty gunk in the carb. Had it happen to me more than once. Everything fine then for whatever reason you give it some beans. The floaty bit moves and covers the jet. Then it either passes through or comes away when you stop and everything rosy again. thats what i was going to say more or less
jimmy Posted April 24, 2013 Posted April 24, 2013 Slice As I (almost)said above, my misfire was on one cylinder only. In fact I rode from Galway to Greenock on 3 pots and when I got home and checked it out, it was the coil.
slice Posted April 25, 2013 Author Posted April 25, 2013 OK thanks all, will drain the tank and check out "FLOATY GUNK" and try new plugs or swap them around and if all else fails swear at it till it stops doing it , that might fail of course but I will feel SO much better afterwards.
Moderator drewpy Posted April 25, 2013 Moderator Posted April 25, 2013 drain the float bowls too, as floaty gunk gets in there. check the little filter on the float valve. fit an inline filter
slice Posted April 29, 2013 Author Posted April 29, 2013 Just for those that kindly answered my query I have found the fault, took the bike out today and all was fine until I had gone about 2 miles then the dreaded misfire came back, been working on it for days and thought I had it pegged but this time I found that the number 4 pot was cold and fiddled with the HT cable and lo and behold found a break in the cable right up under the tank so could not see it until I had my head right up close and there was a damn great spark onto the head bolt, must have worn through some time in the last 30 odd years, so some superglue and a piece of shrink wrap and good as new.
Moderator Cynic Posted April 29, 2013 Moderator Posted April 29, 2013 Well done those intermitant faults are the worst.
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