Misfire at full throttle - Pointy.
 

Hi all. Im new to the site but i've had my pointy SV650 K4n for about 3 years now.:)

I have had a problem from the day I first got her running. I got her cheep from a stolen recovered auction in a very sorry state. No seats, bent handlebars, twisted radiator, broken indicators, smashed headlamp, cracked plastics, dentid tank and scared can :smt019 . Beyond this literny of woes the frame and forks were straight and with a jump start the engine ran sweatly and smoothley. After much scrownging and fixing I got her in roadworthey condition.
She rides well and I have enjoyed her every minuite.
Now the annoying bit. The engine is smoth throughout the hole rev range but if you slam te throtle open she mis fires and gets all Kangaroo. If you then back off and feed the power back on slowley jobs a goodun, or almost. For the next few miles she wont idle and at low revs pops bangs and genraly runs like a bag of spanners.
After 4 or 5 miles all seems to be forgiven. Strange when I tell you what I have done.
Changed both coil packs, changed the fule pump + strainer, checked fule presure and delivery, synchronised the throttle valves, checked the breather pipes, changed both plugs, checked for leaks around the air box and throttle bodies. Checked the EMU for fault codes, adjusted throttle cables, run every fuel treetment and injector cleaner I could lay my hands on, changed the fule pump again (just in case) inspeceted the inside of the tank for residue or contaminates (none found) and gone through the test routene with my multi meater for every sensor listed in the haynes manual. :(
I would class myself as very mechanicly compitent altho I cut my teath on carbs points and pushrods, fule injection and EMU's are not a black art to me ( mostley )
NEXT I went to my local Suzuki main agent.( hate admitting defeate ) Three days later they gave me a call and I skipped down there happy as larry.
"Cant find anything wrong with it" says the service manager, bursting my bubble. Did you ride it I say gobsmacked.
Oh yea its sick I grant you but we cant find anything to explain it. Everything we tested checks out. His only redeaming feature was only charging me one hour labor. Gee thanks.
That was eighteen months ago and as long as I feed in the throtle with care I have had a year and a half of plesant rideing. However lat week overtakeing a truck I opend the throtle a bit too quickly and very nearly joined the angles :smt051 curtasey of the bus comming the other way !!

Can any one make any sugestions ( I'm obsesive compolsive so don't suggest a new bike as I intend to cure this problem or go to my grave with it)
I have considered going to another main dealer if you know one who you can recommend.
Cheers all
Tiptop

Re: Missfire at full throtle
 

Sounds a lot like the old Rover problem of sticky valves. My dad had a rover 75 which done exactly that, including 'remembering' when you've been bad to it. I've not heard it mentioned in relation to the SV but who knows what mistreatment yours had in a past life.

Re: Missfire at full throtle
 

Hi Bud
Thanks for the comment.
I have had both heads off (due to broken exhaust studs) checked the shims, springs, valves and guides.
No visible where or probs.
Cheers

Re: Misfire at full throttle - Pointy.
 

Fuel cap breather? Restricted fuel flow so not enough for full throttle riding. Guessing here :-)

Re: Misfire at full throttle - Pointy.
 

my breather melted to the exhaust and meant the bike got starved and cut out after around 30 miles. Now i guess its plausible that if the breather were like 3/4 melted/gunked shut then that could cause your problem but i doubt it if it was anything like when it happened to my bike

Re: Misfire at full throttle - Pointy.
 

I'd guess you've already tried changing the spark plug leads? Just noticed you hadn't mentioned those.

Re: Misfire at full throttle - Pointy.
 

I had this on mine fairly recently. It was the main lead that feeds the power to the HT Leads/Coil packs-the connector wasn't fully clipped in. Have you checked the wiring to make sure that all of the connectors are clean/clipped together 100% and making good contact?