Rumbling, stumbling, bumbling..

[CB2RN]

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

[coll0412]

You may have to up your main jet a bit, check the jetting matrix

[CB2RN]

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.

[aaronstj]

The rejetting matrix 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. 

[coll0412]

I agree with aaronstj, see if  washer under the needle is enough

[CB2RN]

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.

[CB2RN]

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.

[aaronstj]

Awesome.  Thought that would do the trick.  Glad to hear it's running properly.