Misfires and the like.

[Ceebl]

Right I recently took the wading outa my exhaust to se what it sounded like and then put it back in because it messed up the firing n made it stall n dirty n stuff!
now its put back together properly it still isnt perfect, i dont know now if its related to the exhaust or not!
occasionally itl go off a cylinder and be really crappy n i hav to rev the balls off it to get the cylinder back on, and when im cruising about at like 3krpm and i twist it hard it shudders n missfires before it picks up, u can see the rev counter goin nuts when this happens and at idle when the cylinder stops firing the counter generally goes to zero!!
im just hoping one of my carbs isnt ballsed up again as the bikes under warranty and all mechanical work has to b done by my dealer (usually free because they sold me a bike that has a few probs it seems)
:@
im considerin runnin it on higher octane petrol for a while to see if that makes a difference!

[jambo]

OK,

Could you please provide as much detail about the bike as possible (Year, modifications etc).

There are several things that could cause these sort of symptoms, but the clearer you are on what's been done to the bike, and how long it's been doing this the easier it is to give you good advice. So to kick off:

What year is the bike?
Has it ever run right?
Did you touch anything at all apart from the end can before it started missing?
Have you ridden in the rain / jet washed it about the time it started behaving badly?

Jambo

[Ceebl]

right
2001 sv 650 s
derestricted and had full engine balanced and plugs changed in last few thousand miles, the problems started when i took the wadding outa the exhaust
got better but not completely fixed when i put it back in
unless i havnt put it in right and its cloggin it up wud b my worry
its a beowulf can, not that that makes any difference
erm its been runnin dodgy for the last sorta 50miles since i did this, im doubtin its a wet or dirt as it seems too related to the exhaust timing! i may take the can apart again and neaten the wadding out or somethin!!!

[yorkie_chris]

Full engine balanced? How much did this rob you?

Have you got an air leak somewhere, it sounds as if it could be running lean.

Ahhh hold up... just read the bit about rev counter doing wierd stuff. You've either got the lead to the front coil loose, or a battery or earth lead loose.

[jambo]

Full engine balanced? How much did this rob you?

I would be guessing he means carb balance..

I would 2nd what YC has said, look for loose battery terminals, loose coil leads and loose main relay contacts.

Jambo

[Sid Squid]

Because of this:

u can see the rev counter goin nuts when this happens and at idle when the cylinder stops firing the counter generally goes to zero.

This is good advice:

look for loose battery terminals, loose coil leads.

Your tacho being wierd strongly suggests an electrical/ignition problem is causing your poor running. If the problem were carburation the tacho wouldn't be affected.

[Cidtheratboy]

Hi ceebl
Rode my bike and its good... very good:D
If you have a dodgy tacho and a cylinder misfire its most likely to be the feed to one of the coils, (as the tacho takes its reading from the sig. gen. Do you know which cylinder isn't firing?

[yorkie_chris]

No it doesn't. The tacho takes it reading from the front cylinder coil.

[maclovin]

had the same prob. it was the wire (yellow and black) from front coil , left hand as your sat on bike if i remember correctly

[Sid Squid]

No it doesn't. The tacho takes it reading from the front cylinder coil.
Correct.

[Ceebl]

Thanks guys i need my bike atm for commuting so im soldiering on, hopefully get a look prob 2moro night!!! il let u know how it goes if i get the time to poke about :)
and yeh yorkie i meant get the carbs balanced not engine... my bad ;-)

[joshmac]

I would definitely think it's an electrical problem. I had very similar symtoms as you describe http://forums.sv650.org/showthread.php?t=118457
Play around with the wires to the coils and check both plugs are sparking against the frame.

[Cidtheratboy]

Strictly speaking the tacho takes its reading from, the feed to the coil from the ignitor which in turn takes a feed from the sig gen.
Ok so i missed and giant chunk of that curcuit, but hey i was really drunk. :D