Hawk 250 decided to retune itself?

[Mudflap]

Any chance the jet needle was installed with the clip above the spring thing that holds it in place rather than below it?

[sevndaythry]

No the needle is installed correctly. I took it down the road today and found that once it gets through the lower rpm's ( whenever it can stumble it's way through them) it seems to run good, albeit lean as all get out. I'm beginning to wonder if this is an ignition related issue. Hnu13 has one that I can borrow a cdi from for testing purposes. While I was tinkering with it I noticed that a part of the wire harness was pinched between the fuel tank and the frame and has rubbed a bare spot in the power wire running from the ignition to the cdi( no break just bare) so I reinsulated the wire hoping that was the problem, it wasn't.

While searching the interwebs for a nugget of information to help me solve this dilemma I ran across a guy with a 2stroke who was having a similar issue. In the comments below his vid he posted what he discovered a bolt had backed out of his stator allowing it to wiggle back and forth throwing his timing off. Has anyone else heard of this happening?

So that's my update. Oh yeah, weldandgrind I did a plug chop at idle and the plug looked fine. Not sooty not lean.

Thanks for your help everyone.

[Weldangrind]

Good job on finding the bare spot. That certainly saved you future trouble.

Have you tried a high-rpm plug chop?

[sevndaythry]

It wasn't quite a plug chop, but when I took it down the road earlier I had to run at high rpm/WOT. When I checked the plug after that it definitely looked to be lean. It's all the middle rpm's that are giving me trouble, near as I can tell throttle position is not having s much effect as rpm range is. Idle is fine and higher rpm's are good too but all those revs in between are not smooth at all. I'll try and get some video this weekend, I recorded my ride earlier but I had it in low light mode so it's kinda useless.

[Weldangrind]

I'd move the clip down one notch, and fatten the slow and main jets.

[sevndaythry]

Gonna try and get some jets tomorrow.

[sevndaythry]

I figured I should update this since I hate when op's never post their solution.

I finally gave up and just took it to a shop. For just over $200 they jetted my mikuni carb. I was also informed that my air filter was soaked with oil and would need to be replaced.

IMO this information about the air filter has been my problem all along. With an air filter that is soaked in oil my engine was being starved for air. Causing the unexpected rich condition. I have since installed a cone air filter. I put a rag in the hole where the intake tubed was attached to the air box. Im not sure what I'm going to about the breather tube. I might just make a new "air box" That functions better as a tool box. and has an integrated crankcase breather/catch can. We will see.

[SlowJunk]

Originally Posted by sevndaythry

IMO this information about the air filter has been my problem all along. With an air filter that is soaked in oil my engine was being starved for air. Causing the unexpected rich condition. I have since installed a cone air filter. I put a rag in the hole where the intake tubed was attached to the air box. Im not sure what I'm going to about the breather tube. I might just make a new "air box" That functions better as a tool box. and has an integrated crankcase breather/catch can. We will see.

I just cut a piece of open cell foam (about 1/2" thick) to fill in the 'trapzoid' shape at the bottom of the air box that the breather tube goes to. The breather tube is still attached. You can find small cone air filters to go on the breather tube/outlet, but I never found one that fit the location without interfering with either stock setup or the cone/foam filter alternates. I also found that my breather tube kept splitting so I replaced it with clear tubing that was thicker and can now see if I am getting significant oil suction from the crankcase.