View Full Version : front cylinder misfire
Wideboy
12-09-10, 03:34 PM
front cylinder keeps konking out and is getting progressively worse, gets more violent as bike comes up to "normal" temperature but over the last three rides it has got really bad.
checked it all over, got a healthy spark and everything works as its should but when out and about with the bike up to temperature the front cylinder starts cutting out with the loss of the rev tacho (so its and electrical problem? :confused:). starts off as just sounding a little rough and when revs increased it goes, but after a while the cylinder cuts completely and you had to dip the clutch and give it an aggressive fist full to get it to kick back in. Tuesday night i did 35 miles on the motorway with a constant 7k revs for the whole 35 miles (late and road was clear) without fault but as soon as i came down the slip road and rolled off the throttle it started.
i cant see anyhting wrong so im thinking something electrical is brokeded, coil for the front perhaps?? :smt102
p.s. no its not water in the front plug and yes i have changed the plugs :lol:
widepants
12-09-10, 03:56 PM
gav..are u 100 percent sure its the front one,or is that another daft?
Specialone
12-09-10, 04:13 PM
Fuel blockage?
The fact that a fistful stops it suggests fueling to me ???
Wideboy
12-09-10, 04:15 PM
gav..are u 100 percent sure its the front one,or is that another daft?
well i burnt my finger on teh rear downpipe trying to find out so i'd say im 100% lol
Fuel blockage?
The fact that a fistful stops it suggests fueling to me ???
fuel blockage would be constant problem tho not intermittent? also i wouldnt have thought you would loose the rev tacho? :confused: i duno im crap with electrics
Specialone
12-09-10, 04:18 PM
Exactly whats happening with the tacho when you lose the one cylinder ?
Wideboy
12-09-10, 04:19 PM
it goes straight to zero, not a slow gradient as the revs drop, just drops straight away to zero
fizzwheel
12-09-10, 04:26 PM
Tacho IIRC takes its feed from the coil that runs one of the cylinders, I cant remember which one though. Sounds electrical to me, but I'm no expert where this is concerned.
Liz's SV is doing something similar, tried new plugs etc etc. Bought a 2nd hand coil off ebay in the end but never got around to fitting it, but thats where I'd start in your shoes.
Wideboy
12-09-10, 04:27 PM
im pretty sure it runs off the front coil so unless theres a didgy connection id say it was fubard
Specialone
12-09-10, 04:30 PM
It does sound like the coil mate, if the tacho is going to zero, each cyclinder has its own coil doesnt it?
Swap it over with the rear cycliner see if porblem transfers to the that one.
Wideboy
12-09-10, 04:34 PM
aren't front and rears different?
Specialone
12-09-10, 04:37 PM
Fook knows ????
Wideboy
12-09-10, 04:38 PM
meh jsut bought a second hand one off evil bay so see what happens
Tim in Belgium
12-09-10, 05:19 PM
Check the coil connections, I had a loose one on my SV which caused cutting out at certain engine revs that got worse and worse.
Sid Squid
12-09-10, 06:59 PM
Ditto checking connections, but possibly a dud coil - it's common for a coil whose internal insulation is breaking down to work OK when cold but short internally when warmed up.
If possible swap the colis over, (I don't recall if the leads are long enough to do this), if the problem swaps to the back cylinder then it will be diagnosed.
Wideboy
12-09-10, 07:13 PM
(I don't recall if the leads are long enough to do this),
ah so that will probably be why they are listed front and rear? becasue of lead length
Does sound exactly what mine was doing back in March which turned out to be a dodgy front coil and when that was replaced it was a dodgy coil connector too. The garage replaced the coil and I did the connector, cos I'm cool
Wideboy
12-09-10, 07:30 PM
you certainly are *pats on back* :smt045
Sid Squid
12-09-10, 08:10 PM
ah so that will probably be why they are listed front and rear? becasue of lead length
Very possibly, that doesn't mean it couldn't be temporarily fitted for test purposes though, see if it can be bodged in place - will verify the problem.
yorkie_chris
13-09-10, 09:18 PM
If possible swap the colis over, (I don't recall if the leads are long enough to do this), if the problem swaps to the back cylinder then it will be diagnosed.
leads are different length, you can unscrew them out and swap them.
TBH I'd replace HT leads for graphite core ones if I bought another curvy, seen a lot of the original ones with rot inside causing problems. Plus the graphite ones from halfords are orange, which is obviously faster.
Tacho is driven off coil connector from ignitor box, but IIRC it needs the 12v from the engine too, just the earth isn't enough, it needs to see voltage. Either coil or connector could cause issue.
Wideboy
15-09-10, 06:18 PM
all fixed now, was the coil, picked one up off evilbay and put it in lastnight..... hours test ride proves faultless
Specialone
15-09-10, 06:18 PM
all fixed now, was the coil, picked one up off evilbay
Told you ;)
Wideboy
15-09-10, 06:20 PM
i said in the first post so nerr!!!
this thread is going to get locked and its all because of you two
Specialone
15-09-10, 06:27 PM
Bol...........ox
Lock it, i aint bovvered
lukemillar
15-09-10, 11:08 PM
Told you ;)
Erm.....post 3?
http://forums.sv650.org/showpost.php?p=2367959&postcount=3
:wink: :p
Specialone
15-09-10, 11:10 PM
It does sound like the coil mate, if the tacho is going to zero, each cyclinder has its own coil doesnt it?
Swap it over with the rear cylinder see if problem transfers to the that one.
Erm.....post 3?
http://forums.sv650.org/showpost.php?p=2367959&postcount=3
:wink: :p
Erm read all of them :rolleyes:
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