Join Date: Nov 2008
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Low RPM load issue - lots of detail
Hi Guys. I love my 600RR but it's got an issue and I've searched but not found anything that looks like it's the same problem a mine. Similar, but not quite.
I have a 2003 600RR with 32000kms (about 20k miles) that is entirely stock. I rode the bike before buying it and it was all good, but, the issue is only present when warmed up so either it wasn't there, or I didn't replicate the conditions.
When warmed up the idle is not smooth, it's between 1200-1600. When I put it under load at low throttle and low RPM (less than 4000-5000) it misfires. I put plugs in it and it masked the problem for a day. This misfire feeling is only there at low RPM AND low throttle. Below are some situations:
1) bike is cold, bike idles higher than warm and all is smooth, runs good.
2) bike is warm, 1st gear, 3000rpm, level ground, pulling away from the light I feel misfire
3) bike is warm, 1st gear, 3000rpm, hill start (deeper into the throttle), smooth acceleration
4) bike is warm, 5th gear, 2500rpm (for diagnostic purpose only would I do this) gently on the throttle, just barely, not bogging it, the "misfire" is violent. Crack the throttle briefly just to see, and the misfire goes away with more load.
5) bike is warm, cruising around in any gear really, 4000+, with any amount of throttle, smooth power. So having very little load but having some engine speed helps.
Last night I shot some brake clean as best I could into where the TB's are while it was running to see if there were any air leaks and my idle didn't go to crap so at first glance there aren't any air leaks.
I'm hoping the long post didn't scare anyone away and that you're able to help. Thanks guys. I am reasonably mechanically inclined so I'll try out any suggestions and report back.