I'm having a similar problem. I've partially cleared it up so it seems to run fine, but when I put it in gear the symptoms return. Pull on the clutch, even in gear, and it throttles just fine. Try to accelerate with anything beyond light throttle and it starts to bog around 4k. Opening the throttle completely just makes it die until it reaches about 1k and it comes back. When this problem started it would bog even in neutral standing still, so at least I've made progress! For me it all started on my 2nd tank of gas after sitting for the winter (during winter I stored it with a full, treated tank and empty carbs. Ran through that tank with no problems).
Here's what I've done so far:
1. Pulled spark plugs, no fouling. New plugs.
2. Drained fuel tank- no rust. Treated fuel (LOTS of seafoam. An older forum I read suggested 6x the mount listed on the bottle) and refilled.
3. Drained carbs, filled with seafoam and let sit for a week (went on vacation). Came back, emptied seafoam and it came out clear.
4. Disassembled petcock- VERY clean and no blockages.
5. Checked fuel lines, all clear.
6. Backblew carbs (can't remove the rubber intake boots though without stripping the screws).
7. Checked for POOGS (a problem I used to have on this bike), everything there looks fine.
8. Made sure carb vent hose to right ear was clear and cut to 45 degrees.
My only real theory so far is bad fuel. But that's got to be some SERIOUSLY bad fuel. That or a blockage in the one of the jets, but I really really don't want to have to pull those things. I'm more mechanically inclined than your average joe but I really have no idea how to go about pulling these carbs.
-edit- Now that it at least limps along, I'm thinking I might drain this fuel out to just the reserve amount and ride to a gas station about a mile away and top it back off. Is there any hope that it really is just a bad tank of gas, given how much I've already treated it?
Last edited by bluguitar89; 04-01-2015 at 09:04 PM.