Sooty Plugs, Misfiring Problems?
 

Hi,
Hope someone can offer advice on the following, I have an SV650S 2003 (EFI Model) which has developed a running fault.

The bike starts OK, and seems to tickover (a bit high 2000rpm) but when the throttle is used (pulling away at low revs) the bike splutters and misfires until you get to around 4000rpm. At this point is pulls OK, if a bit 'rough'.

I have changed both plugs, cleaned the air filter, cleaned the fuel filter, checked the gap on the plugs (0.7mm).

When I have checked the plugs they are both very 'sooty' with dry black deposits.

I did initially suspect the HT leads to be the problem, but having searched the forum I am now wondering if the Throttle Position Sensor may be the culprit?

Would be grateful for advice from anyone else who may have had a similar problem and any ideas on fixes for the problem.

Heres hoping.

Re: Sooty Plugs, Misfiring Problems?
 

Sounds like the bike is running rich i.e. there is too much fuel, so it dosnt correctly combust (hence the soot deposits). Are you able to try balancing / synchronising the throttle bodies?

2000 rpm idle is high, unless of course its from a cold start (say first thing in the morning) and its the choke cycle. An SV, once warm, should be idling between 1300 and 1500 rpm ideally.

I'm not certain what to suggest; if it were a curvy (carb'd) bike I'd be pointing at the chokes on the carbs, I'm not sure what the analogous part would be on a pointy

Re: Sooty Plugs, Misfiring Problems?
 

Temp sensor perhaps keeping it on its cold start enrichment setting.
Maybe TPS but probably not unless it's miles out.

Re: Sooty Plugs, Misfiring Problems?
 

+1

Sounds just like my race bike did last week, TPS was out, set it and mint!

Re: Sooty Plugs, Misfiring Problems?
 

http://www.sv650.org/sv_faq.htm#Adjusting the Throttle Position Sensor (TPS) on a 2003 - SV - this one might help re the position sensor if you wanted to read more?

Re: Sooty Plugs, Misfiring Problems?
 

Go with what YC suggested, looking for a temp sensor. It might be all crudded up and could be an easy fix. then if its still not right...check out for the TPS.

Air leaks a possibility anyone?

Re: Sooty Plugs, Misfiring Problems?
 

sounds identical to the running fault i had. turned out to be the throttle position censor. a garage bill later and jobs a goodun. runs better than ever, now getting 190miles out of a tankfull compared to around 145.

Re: Sooty Plugs, Misfiring Problems?
 

Thanks Guys,
Adjusted the TPS, which has certainly helped, still a slight misfire at 3000rpm however, will try and adjust it again to see if it cures the problem.