I guess rough isn't the right word for it. It idles perfect, revs up perfect, if I get on it past about 1/2 throttle it runs perfect and if I'm below 1/8th of the throttle it runs fine. In gear between those two points it constantly surges and then loses power and sputters a little bit. It never gets close to stalling or sputters/surges too violently. I've replaced my plugs/wires/coils/cdi/carbs trying to fix it and nothing did the trick. any other suggestions?

 

Sounds like a textbook slipping clutch to me. Do your RPM's go up and down counteractive to the surges? How much "play" do you have in your clutch lever before you can feel it pulling up the plate (please measure)?

 

Not much left to replace, check the clutch

 

Bad solenoid valve? mine kept coming unplugged from one of the hoses that runs to the center cowl, and it did exactly what you're describing.

 

It's definately not my clutch slipping, I have a lot of clutch to go before I need to replace it. It starts pulling up the plate within 2cm of pull. They don't go counteractive, but rather with the surges/sputters.


Bad solenoid valve, I'm going to have to check into that for sure. I actually think I deleted that when I cut my wiring harness down thinking it wouldn't make a difference. If that's what my issue is, is there any way to bypass the valve? It's a stunt bike, so I'd like to keep it as cheap as possible.

what exactly does the solenoid valve look like? it's not the small black box wired into the wiring harness, is it? i'm guessing not seeing that you said it was attached to the hoses. When your's was coming undone, you could still get it WOT and it wouldn't lack power at all, right? did it act almost like a misfire at times?

 

this is a bump. sorry guy's, just trying to get as many suggestions as possible.

 

Check the fuel pump to make sure it is working properly. This happens a lot. Maybe a dirty fuel filter?

 

Download the shop manual from Stephygee's site. Then look at page 5-5. It has the routing of the hoses and the air vent solinoid.

 

You mentioned carbs but what did you do to them?

You also mentioned the bike not running right between 1/8th throttle and 1/2. What about 3/4 and wide open?

 

I have the manual and have concluded I'm missing this air vent solenoid altogether. I'd guess that this is my issue, only thing is the bike ran perfect for the first 3 or 4 months of owning it. the problem has become consistently worse since then and I wasn't the one to remove this solenoid.

As for the carbs, I replaced them with a warranteed set from ebay that were ultrasonically cleaned and synced to stock settings. When I'm above about 1/2 throttle it runs perfect through all rpms same with below around 1/8th.

I tried bypassing the fuel pump with a full tank of gas and I still had the same issue. I looked at my plugs just to be sure oil wasn't passing through and fouling a plug or something along the lines.

I think I'm convinced the air vent solenoid is my issue.