250-500cc WR300 jetting and tuning thread

After my initial ride the other week I noticed that the bike was jetted very rich in the mid/full throttle positions and was spooging like mad out of the silencer. So yesterday I set the float level to 14mm, raised the needle one clip (from #3 to #2) and put in a 450 main (460 was stk).
I went for a ride today and must say it was a huge improvement!

I could tell a difference just warming the motor up from the staging area. It revved crisp and clean without the usual blubbering and smoke screen. Once warm, I took it out and it felt much better than the previous trip. The pilot jet is too lean and I did not have a larger size to test, but once it got onto the needle and main circuits it was hauling! That's one kick ass motor I wish I had a larger pilot with me cause I think it would have helped with the bottom end lack of snap.

Temps were between 40 and 50F, humidity was probably around 80-90% (I guess!?!?) and elevation ranging from 1000 - 2500'. In these conditions, on my bike, I found it needs one size larger pilot, one clip position leaner on the needle and one size smaller on the main. I did a WOT chop and the plug looked great. Nice brownish tan color.

Did I mention that motor rips!?!?

Hey BRandon..what are using for oil...and what ratio ??

Correct.
Thanks for the correction.

Klotz R50 32:1 w/ Chevron 91 pump swill.

Thanks for the tips! I hope to get my WR out for its maiden voyage within the next week or 2.

Yesterday was my WR 300's second voyage. We're at 500-700 feet elevation and it was in the mid 50's. I've still got a mild burble right off closed throttle. I lowered the needle one clip and haven't touched the main. At yesterday's conditions, the 300 ran flawlessly except for the slight burble immediately off idle. I'm may try a smaller pilot when things warm up.

I'm amazed at the huge difference in performance in these Husky 2T's after they're broken in. Both the CR 125 and the WR 300 exhibited major performace differences between new and fully broken in. I could literally feel the changes as I rode both bikes on longer break-in runs.

I hear ya!
Husky must have some pretty tight tolerances cause the motor's need a substantial amount of time before they're running full tilt. The suspension must have NASA-spec tolerances. I'm not sure its ever going to break in!

I could not get rid of a lean pulsation at idle until the air screw was at 1/4 turn out. I was very lean on the pilot in somewhat similar conditions. The biggest change was dropping the needle. I could have left the 460 main in there and been happy.

Ride on

Today I put a 30 pilot in my WR300 and the off-idle burble is gone! So far, I've lowered the needle a clip (raised the clip one notch) and put the 30 pilot in. I may try a leaner main when the temps get above 70. At current conditions (500 ft. and 55-70 degrees F) the WR300 is running like a scalded dog with the 30 pilot and lowered needle. No burble so far at WOT. Stay tuned...

I picked up an '09 WR250 three days ago and the clutch is not fully disengaging in gear so the bike wants to start moving once in gear even with the clutch fully pulled. Does the WR300 have this same issue? The shop I bought it from says this will go away once it has some miles on it. Any comments? Also, my bike doesn't idle. I'm thinking of setting an idle per the instructions on page 92-93 of owner's manual. Does your WR 300 idle?

I do notice more clutch drag on the Husky than other bikes I've ridden, but not to the point where it creeps forward while in gear with the clutch disengaged. It is a pain to start in gear due to the clutch drag, but that's the worst of it.

How much free play do you have at the lever/clamp junction? It should be about 2-3mm.

Mine did not idle when new. I had to crank in the idle screw 3-4 full turns before it would idle.

The 300 doesn't have any drag. My CR 125 has a tad. I suspect it will get better as the clutch wears in a bit.

The idle on both my WR300 and CR125 increased as the bike broke in. I had to adjust both down a bit after an hour or two of break-in.

I did a little testing this weekend. Elevations between 700-2000', temps in the low to mid 60's and low humidity.

30PJ
stock needle #2 clip
460 main
floats set at 14mm

About perfect for me. The larger pilot was a necessity for me as I could not adjust out a 'lean surge' with the stock 27.5pj. With the 30 I have quite a bit of wiggle room to use the air screw for fine tuning. I get a tiny bit of pinging on the needle. I think I need a 1/2 step richer needle in the middle. Anyone familiar with Mikuni needles and can name it?

The motor is also breaking in nicely and making some power. This thing makes stupid power, but the rear time always hooks up. Not sure if the 18" wheel has some bearing on this as I've never had one before or if it's just a characteristic of the motor. Regardless, this this makes traction and lots of it.

I call it my Jekyll and Hyde bike. Under 3/8 throttle it's docile, timid and able to lug up anything without complaint. After 3/8 throttle it gets onto the pipe and starts wicking it up. Fast. It really feels like 2 entirely different motor's.

Yours came with a 27.5 pilot stock? Wierd... mine came with a 35 pilot stock. I'm torn between a 32.5 and 30 after some test riding this past weekend. I think I'll eventually end up with the 30. I've also gone to a 450 main with the clip in the 2nd notch. With the 32.5, I still get the slightest off-idle burble. With the 30 pilot and the 450 on the second notch I get crisp response in every situation. This 300 is an absolutely wicked ride.

Bill had rejetted my WR before I ever picked it up so he could have done the same for PC

Sorry, wrong info. Got my data confused with another machine.
Thank God for notebooks. I'd have blown up 10 motors by now if I only had memory to rely on!

It did come with a 35 stock. I'm running a 37.5 now.
Once the summer heat gets here I'll be putting the 35 back in, but I doubt I'll go any lower.

Has it been real humid out East? Or are you riding at higher elevations?
I'm wondering what the difference is.

OK guys, I've a question about basic, external carb tuning at this point as I'm coming from a 4-stroke FI background. I took my WR300 on its first ride today and my thinking is that the bike is a little starved for air as I was at 7300-8500' of elevation. It won't even idle right now unless I'm keeping the throttle moving. Anyway, I did several heat cycles.

I was reading the manual and it states that the mixture screw from the factory is 2 turns out. I assume this means that with the screw in the pic below, bottomed out, it is backed out two turns. At my elevation, I assume it may need to be out more than two turns. Now, I believe I read somewhere that if it's out more than two turns the jetting should be changed, but that's another topic. I found it was out 1 and 1/4 turns, so I assume this means it's more restrictive than stock as far as airflow. Do I understand that correctly? I guess I can try turning it out to at least two turns and see what's what


Now in this pic, what I'm pointing to w/ the screwdriver is the idle speed adjustment, correct? I think I understand that one a little better than the mixture as I turn it clockwise and the RPM increases.

Pipes

Is there anyone that have tested a 250CR/WR pipe on a 300WR?


Klas

From what I understand, the expansion chamber was changed specifically for the 293cc engine. i haven't read about anyone swapping pipes. sorry

Wyatt Seals has been working with Pro Circuit on a pipe for Glenn Kearney's WR 300 for months now. I'm hoping to see a 300 pipe on the market soon.