sv650s k6 engine dies at about 5000rpm help!

I have an issue where if my wifes SV650S K6 is rev'd to 5000rpm (or actually just shy at around 4850rpm) the motor cuts completely. It bangs like a shot gun from the exhaust when it dies too.
Up to this rev point it revs ok. Not really crisp but not missing and starts and idles ok. Everything seems fine until 4850 revs then it dies.

This all started after my wife complained the throttle was abrupt when she opened it in a corner. I rode it and didn't think it was too bad for an FI bike but it was there and after a little research it seems the setting of the TPS via the dealer diagnostic mode display could improve this. So I followed the instructions from this site, found the display bar central at tickover but didnt move until 4500rpm. So a few tweaks of the TPS anti clockwise and a couple of idle speed changes and all looked good. Took it for a test ride around my local streets and it didnt really run that smooth and completely stall on me when I tried slightly harder acceleration. Thought i might be pushing home but it fired up and got me there. Since then my home testing has shown the above issue.
It may be throttle position related rather than revs it difficult to say, slowely opening throttle it cuts at 4850rpm. Quick blip from tickover and it cuts out too with loud bangs that scare the hell out of our dog. But the revs go up so quick on the tacho hard to say if its position or going just its going pasts 4850rpm.

I have just noticed if I slowely rev it with the clutch pulled it gets to about 5500 rpm before stalling out with a bang. Also if I move the TPS back to it oringinal position it cuts out at a few hundred rpm higher.

Checked Main TPS and Secondary TPS volts supply and resistances from 0 to 100% and both read close to what my Haynes manual states. No obvious jumps in resistance as they open either.

Any ideas everyone?

Cheers.

Sent from my SM-T285M using Tapatalk

[SV650rules]

Almost sounds like rev limiter cutting in.

[Craig380]

I wonder if there's some dirt or corrosion in the TPS itself. Might be worth removing the TPS sensor from the throttle body and seeing if there's any crap in there, and giving it a spray with some electrical contact cleaner.

Update - thanks for your input. I've been working away but have now checked the TPS closer. Taken it off and checked ohms through rotation. All normal I dont think this is the issue. With the TPS disconnected the bike runs and back fires just the same. With the TPS plugged in but not connected to throttle it runs the same. ritating the TPS with the engine running with steady low rpm seems to lower rpm like its fuelling even richer.

My next checks involved the Diagnostic plug itself. There are 4 wires in there, the red/wht and blk get connected for diagnostics mode - but what are the other 2 wires for?

One had about 7 volts and the other about 12 volts. But what is there function?

Any ideas out there, thanks?

Sent from my SM-T285M using Tapatalk

[R1ffR4ff]

Have you checked the Spark plugs/gaps and the Spark plug caps.If the spark plug caps have a Resistance above 10k ohms there could be a fault causing higher end speed restrictions as could faulty Spark plugs.

HTH

Originally Posted by R1ffR4ff

Have you checked the Spark plugs/gaps and the Spark plug caps.If the spark plug caps have a Resistance above 10k ohms there could be a fault causing higher end speed restrictions as could faulty Spark plugs.

HTH

Thought I'd update on the progress here. I finally had some time to get stuck in testing everything. I made a list of possible causes and used Haynes manual to get the correct specs from. Everything checked out perfectly. But some strange things occured. Using a spare spark plug I got sparks from F & R cylinders. But when testing the installed plugs only the front sparked. Aha i thought, changed the rear plug for new, got sparks ok but problem persisted!
I tested alternator output which was good, but now the motor would rev out with it disconnected, so suspected rectifier unit or alternator. Tested both and they were ok??? I was cleaning all connections as I teasted. Bike was now mostly free reving but woolly sounding so back together for test ride. It ran on one cylinder for 2 streets and then back fired at anything from 2k rpm. Limping home I was contemplating pushing it back to avoid ****ing of neihbors from the noise but the second cylinder suddenly kicked in and it started purring like a kitten. Carried on for 30 min test ride and have now done another longer ride without fault, the engine is smooth running again.
So annoyingly inconclusive out come but she runs well again.

Sent from my SM-T285M using Tapatalk

[R1ffR4ff]

Thanks for posting back.Fingers crossed you have got it beat