Engine missing and losing power.

I'm racing a 2000 SV650 and am having a reacuring problem.

The bike has run great last season, but after running well through practice and racing on day 1 of racing this season, on day 2 the second race it started missing horribly and lost major power.

The shop I brought it to, changed plugs, changed fuel and cleaned the carbs. The bike again ran fine day 1 of the next race weekend, and then on day 2 the same thing happened. I am running fresh pump premium gas in it.

I did bounce the bike off the rev limiter a bit longer than usual going into turn one, and it started running poorly after that. This may have happened on the first weekend too, I don't know.

I have replaced the plugs myself, and drained the tank and see no dirt in the fuel. The bike is still running poorly, and a big race is coming up this weekend. Any help appreciated.

Background. Nothing new has been done to the bike prior to this season and these problems.

The previous owner put an M4 exhaust on the bike. It has a stock airbox. No engine modifications have been made. I don't know if the jetting was changed at some point, but i have not changed it and ran very strong last year with it. And this year when running good, it was as strong as any SV on the track.

Thank you for your thoughts and help!

David

[rictus01]

have you checked the normal loom wear points? could also be a coil on the way out, just off the top of my head.

Get the bodywork off and the tank up, see if you can replicate the problem by wiggling the wiring at various points, may help track it down.

If that doesn't work, look at plug caps, HT leads, coils and coil feed wires.


Cheers Mark.

Thanks for the suggestions Mark. I'll try wiggling the wires now - it's still running like junk even with the new plugs so I'll see if that cleans it up. The plug wires and caps looked good, but don't know about the coil or it's wires - great suggestions, thanks so much for your help!

Will let you know what the result is...

Be well,
Dave

I tried wiggling wires and checking the plug caps, w/no success. The bike has now been at the shop all day and they can't find a solution. They are going to check now to see if it could have a broken valve spring but I doubt this is the issue.

Is there any way to have them test the computer on this? They are saying they would need to install a new one to see if that was it. But I don't want to spend it if that's not the issue.

Also - I don't know what you mean by "loom wear points"?

Any help would be appreciated. I'm getting short on time - I need to leave for the race tomorrow! YIKES!!!

Thanks,
David

[fizzwheel]

Originally Posted by LoudonSVracer

Also - I don't know what you mean by "loom wear points"?

The wiring loom rubs on several places on the bike, then the wire insulation wears through and you get a short, places to check are :

In and around the rear subframe under the plastics
Riders seat bolts.
Round by the headstock.

Originally Posted by rictus01

have you checked the normal loom wear points? could also be a coil on the way out, just off the top of my head.

Get the bodywork off and the tank up, see if you can replicate the problem by wiggling the wiring at various points, may help track it down.

If that doesn't work, look at plug caps, HT leads, coils and coil feed wires.


Cheers Mark.

Mark is it possiabe that the carbs are blocked and gummed up as that what is the suspect fault on my race bike. That is something that is being done and checked, cleaned ect. My bike is the same year as this dude's as well....

Just a thought I could very wrong (after all I know jack) but sounds simlar to my problems at Silverstone what do you and others think, could it be that?

Mate good luck with the bike, hope you get it fixed, Chris