2000 SV650S misfire.

[Sv650sDan91]

I have recently purchased a SV650s 2000 and there is a distinctive backfiring when she's on idle. I try to increase the rpm to 3000 and the backfiring just get louder and sounds more harsh, this backfiring occurs on pretty much every 4th beat.

I have given her a full service with new oil + filter, air filter, spark plugs, brake fluid & coolant. I took it to my local garage where they said the backfiring was caused by having a 46.6 restrictor fitted (which this is rubbish because it done it before I had it fitted) and so I asked them to set the mixtures + balance the carbs, I picked her up a few days ago and still the problem is there. They tryed then blaming it was the aftermarket exhaust as well but I have my standard exhaust back on again and still no difference so I've swapped it back to the aftermarket viper exhaust.

Could someone pleae give me some help/advise on what this issue could be caused by would be very much appreciated!

Ps. I sacked off the garage I took it too and I believe they have now gone out of business!

Cheers Dan

[yorkie_chris]

Air leak perhaps, could you post a video?

Also where are you located?

[Sv650sDan91]

Couldn't find any air leaks or any problems with back pressure from the exhaust systems, i'll pop a video up and i'm down in the south west in Exeter, Devon

[Sv650sDan91]

Heres a video of what its doing

https://www.facebook.com/photo.php?v=10151850617586014&l=1056989957821826623

You can clearly hear it towards the end of the video

[Bibio]

i'll let YC answer this properly, but to me it sounds like a dodgy coil or a sticky float needle?

[Spikey12]

i get the same problem, i'll be keeping a keen eye on this thread then :P

[yorkie_chris]

I would still say air leak, but obviously you can't be 100% until you start messing about. Try some squirts of carb clean or something around the intake boots etc and see if it changes the idle. Look for cracking, perished vacuum pipes, perished cover on front balancing nipple...