250-500cc WR 250 - Loss of Power and Lots of Spooge

Yeah, that jetting setting is very nearly what I am running in my bike (or was, I am experimenting with different needles now). JD red in the 2nd clip is my normal summer setup, and then I move it to the 3rd clip (a bit richer) for colder weather. I think I am on a 45 pilot, but 42 and 45 should both work. I would NOT change your jetting to try to "fix" the spooge problem, if you do that you may run a risk of doing damage due to being too lean.

I am doubtful that the top end is toast, but it's possible that it got damaged. I'd do a compression test.

Sounds good, thanks Kyle.

I just put a JD kit in my '08 WR250. The 'Red' needle is Richer vs the 'White' needle being leaner. Sounds like moving the clip up or down one spot is about all you want to do. Like Kyle said above, running it too lean is a huge problem. Some Spooge that runs down the silencer is normal and not all bad. Spooge all over the back of the bike, rotor, sprocket and swing arm would be excessive - IMO.

^^^
What needle are you running on your 2008? I wondered if that kit was meant for the newer TMXX carbs. I tried the white needle and it was crazy lean, I think I put the red in and was still lean. JD gave me another needle to try, but I never put it in. The stocker runs really well in my 2008, 3rd clip.

Just did a compression test with following conditions:

Pipe, silencer and carb (cleaned but not changed) installed.
Engine cold
Wide open throttle per article I read online on compression testing.
Air filter, medium dirty, out of bike.
Power valve side covers removed.

Highest reading i got and it took several tries was 185.

Next, I'm going to put tank on and run bike to see if power valve rotates. Will do another compression test then.

185 psi is good. Your topend is fine.

Spark plug ok?

Won't be able to run it tonight.

Did another compression test with a pretty clean air filter and got the same 185 as before.

How's that number? Article said a 250 2-strike should be between 170 and 240 psi. Couldn't find a number in the service manual.

The stock 250s have more cranking compression than a 300. If you buy the race head for the 300 it will get up there toward 200psi. otherwise 185 is good for a stock 3hunny. My stock 09 WR250 has 205psi and won't run on 93 pump gas without detonation.

I didn't see where anyone asked if you were losing gear oil from the transmission or if the spooge stank like gear oil. It's not a common problem but there is a possibility the trans side crank seal could be letting oil in the cylinder fouling up the combustion process.

Lankydoug - Spooge didn't smell like gear oil. In fact, seems like I rarely go through oil.

Kyle - Plug from morning ride when things went bad is medium gray. New plug is slightly lighter gray. It was only in for about 30 miles. Picture attached is the old plug.

I plan on running it tomorrow with the left side power valve cover off to see if the mechanism rotates with throttle application. I assume doing this in neutral is ok?

I cleaned up the right side mechanism and put that cover back on after doing the compression test.

I guess after running bike tomorrow I'll drain gas from carb and do another compression test. Would putting that right side pv cover on make a difference in reading? Does pressure escape from there? I assume yes since unburned oil ends up getting into that area. Maybe my readings will be even higher.

That plug doesn't really look that bad... Not perfect but definitely not filthy rich. I think you're going to find your problem somewhere besides jetting.

Cool, thanks.

One more thing I noticed tonight. The spark arrestor screen is about half clogged with dried up crap!

Also, the rubber collar was slid down off joint between stinger and silencer. Maybe it wasn't really a large quantity of oil but it just found the path of least resistance? Saturated packing, clogged screen, so went to the open joint and dripped on swing arm?

I bought it like that, also.

After tomorrow maybe I'll know more.

I cleared the clogged pilot jet. Maybe that solves the mid and top end running problem. Maybe it solves all problems. I'm making the pipe work for these tests in it's mangled condition. I just ordered an FMF Q Stealth to replace it.

Next, drop the needle/raise clip to lean it out a bit and reduce spooge volume?

Or, would I just adjust the air screw on the outside of the carb?

I know I'm looking for tons of answers. Maybe this process will help somebody out in the future.

Ordered an fmf q stealth. Arriving tomorrow. Hopefully it helps.

If the spark arrestor is significantly clogged, that could be a big factor here.

Heck yes! a string weed whacker won't even run with a dirty screen.


I avoid screens on all 2 strokes. I bought a Q-Stealth for my wr250 and it is quieter and doesn't use a screen type spark arrestor.

The stock silencer wasn't bad just heavy and many complained that they were hard to repack and the mounts were easily broken. I had no problems with mine and still have it for a back-up spare.

Can I just mention, I had this drama and it was after a wave, yes a wave, I played in the edge of the surf on a beach ride.
Ran like crap, just wouldn't climb into band !

Was a bad connection under tank, drunk fuel, ran like shit, cleaned and lanox'd the connectors, ran like a scalded cat afterwards ! (Was a 2010 tm300 )

PowerKord - I'm running the White 'lean' needle in the stock '08 carb. I forget what clip I'm on (written down at home). I'm running my premix at 40:1 and my air screw is out 1 & 1/8 turn out. It runs great right now at 90 deg and 85% humidity. When the temps cool down, I'll need to back down the air screw to richen it up some. If that air screw goes much less than 1 turn out, I'll probably put the RED needle in it for the Fall and Winter months. - Just FYI