2011 ASII 36 Jetting - what were they thinking?

[Neil E.]

The monsoon season is over here. I got out for a first ride with some buddies. The jetting is so rich, it runs like the air filter is totally plugged. They must have intended the jetting to be used at 20*F at sea level.

The stock settings: 6.5 slide, 42pilot, 175main, N1EF, 1T air screw. The bike idles (sort of) and the air screw has little effect. There is no "get up and go". I'm using Ipone Samurai at 50:1 and the riding is mostly singletrack. Elevation 1000 - 1200', temperatures 60-80*F.

The exhaust sound is dull on accel or decel. After about an hour of riding I notice a distinct knock from the engine on decel. Soon I get this knock on every gear change (when I close the throttle to shift). Time to head back to the parking lot. Keeping the throttle steady helps.

Burhan (EC300) tells me that the manual recommends changing the plug after the first hour of operation. I put in a new NGK (the plug in the bike is a Nippon Denso).

Head back out and everything is OK again. The engine runs marginally crisper (still a long way from crisp). After an hour, the knock is back. Soon it's getting dark and time to end the ride.

The next day I pull the NGK (left) to compare it to the Denso (right).



My exhaust tip is messy and the inside is very oily. I'm not worried about spooge, the angled outlet does a great job of keeping the rest of the bike clean.





Having a stock needle that is crazy rich with the clip already in the top groove is nuts. Not even one groove of adjustment is possible. Have any of you 2011 owners found a needle that runs well with the clip in the center groove?

I'd like to know what the cause of the "knock" is. It's just like a single "pre-ignition" detonation. I can only guess that fuel mixture builds up in the pipe and ignites.

[Bailey28]

The knock, or "kack" as I call it is the exhaust loading up with unburnt fuel. It will happen if you don't "clean it out" after warming the bike up after you first start it too. (Get the bike on the pipe for a few gears)

I had to go a little leaner on my jetting on my 300 to get that to stop. I also noticed that if I am in the woods all day, I could use leaner overall jetting vs. riding a motocross track as I also do on my 300.

Unfortunately I cannot suggest jetting changes for your 250 specifically, but I can say that you may want to go leaner.

[mrkartoom]

I agree I'd go down pilot size a step at a time to see if that improves it. 42 seems kinda fat to me, but can't say for sure. GMP has a lot of experience with 250's I think, he may know what that needle and slide will run with in that carb. He may chime in. I've got a good setting for a 250, but different carb and slide so it's no good to you.

What is that snorkel?

[Neil E.]

That is a piece of 316 stainless steel dairy tubing, specifically a 1" x 45* long tangent elbow for TIG welding. I machined up an adapter to fit the muffler end cap and silver soldered the tube in. The adapter has a tapered bore and is a snug fit into the muffler. A bead of medium temperature silicone holds it firmly in place.

On my first parking lot ride, my jacket stunk of 2T oil. The Krizman "bullet" is very near the rear of the muffler and makes the exhaust swirl enough to deposit oil mist on the fender. Some oil mist also gets drawn into the still air pocket behind the rider. An angled tip was an easy way to stop this. A side benefit is the exhaust is directed away from a following rider when on the trail.

I like that the angled outlet creates a "drip point" for spooge; that way it can't run back down the muffler.

[mrkartoom]

Good job. Has that factory look.

[Jakobi]

The sound.. Would describe it as a "GUNG!!" only ever one. As mentioned its the exhaust loading up with unfburnt. Usually a sign of a rich pilot and happens on decel.

Same settings my 2010 300 came with on a 300 with 38 mm pwk asII.. My plug was the same.. Still chasing the answer somewhat..

[biggstr6]

my 2011 EC300 sixdays has the 36mm ASII 6.5 slide and was crazy rich as well.

I got the YZ needle N3eJ , went to a 40 pilot & 180 Main and it made a world of difference . Sea level - 2000 ft ,80 degree temps.

Havent had a chance to check the top end WOT yet ,but 1 & 2 and right off idle are much better.

I copied the settings from Reverup.