I've noticed a significant stumble under heavy throttle, always between 6000 and 7000. It may go higher than that, but I've never gotten past the onset. I re-jetted the bike (40/127.5) thinking it would improve, but no luck. The rest of the system is a V/H pipe with a stock airbox & filter. Any ideas? Is it an ignition advance problem? I haven't looked into that just yet. Something else I'm missing?
Thanks
You may have to up your main jet a bit, check the jetting matrix
As far as I know, That's what the matrix suggested. I double checked a couple of times before I ordered. There was no change with the jet change.
The rejetting matrix (http://www.angelfire.com/mt2/mikesgs500/rejetting/Rejetting_Matrix.html) doesn't look to have a recommendation for a performance exhaust and a stock filter. I don't think I'd recommend running with that setup, I'd match the exhaust with a lunchbox filter.
Even without changing your filter, you're probably still rather lean. I'm thinking you could push as high as 140, but that's just a guess. The first thing to try would be washer under the needle, though, which can easily be done without pulling the carbs. The actual settings you want are a total guess on my part, but I guaranty you're lean. I had the same symptoms, until I moved to much larger main jets.
I agree with aaronstj, see if washer under the needle is enough
Sounds like a plan. Do I just get regular machine washers or do I need to order them like I did the jets?
As far as the exhaust, I'm going to be switching to a SV650 stock can on the V/H's pipe. I didn't set the bike up the way it is now, just inherited it. I was thinking of going with a Uni filter as well. We'll see.
Well, 137.5 got rid of the stumble. I forgot to check the washers, so that's on the to do list.
The bike runs mucho better now. I still need to do an exhaust update and then rejet again.
Awesome. Thought that would do the trick. Glad to hear it's running properly.