11' 250 race-wa. jetting?

[adv rider]

New to forum, picking up an 11' 250 race this week. I am wondering about what jetting people are using here in Washington? I have been on a 4 stroke for last 7 yrs, happy to be back with a 2 stroke. But I am worried about the jetting, as I plan to go to desert 100 with the new bike. I am hoping to get the jetting close and usable- I don't want to foul plugs or burn up the engine. I will probably get to ride once at Walker valley before the Desert 100
I did a search, but did not find what I was hoping to find
Thanks for the info

temps can range from 30-60 degrees, and elev from 300-1800'

 

[Jakobi]

Confirm it has an AS2 carb, check the float heigh as per stick at top of this section. Get a Yamaha needle N3CW, and an N3EW for half clip adjustments. Start with clip in pos 3, 40/42 pilots, 178/180 main, and fine tune from there.

 

[adv rider]

250 race jetting

Thanks for the info, i am going to try and get the jets today. Picking up bike tomorrow-can't wait to try it out!

OH, I almost forgot-wouldn't it definately come with the as2? I don't have the bike in view, but wanting to get the jets today.

 

[Jakobi]

It should, but in previous years and even at least one I know of last year, they have come with some variation due to supply issues. The AS2 has the small flat steel cap, shallow bowl, and on the cap the size will be printed. 36 or 38. The as1 has a screw on round cap and deeper bowl. They all jet differently so it pays to check. Odds are you'll have the 38mm as2 though.

Are you buying new? Theres a few things I'd do before riding the bike (like almost every other brand out)

 

[adv rider]

11' xc250

It is a new bike. I plan to go through everything, grease linkage, clean re-oil air filter, etc. I hope it turns out to be a great bike for me... I was really wanting a KTM. But I've been proven wrong before.
As soon as i pick it up in 12 hrs or so, I will see exactly what carb it has and get the appropriate jets

 

[Jakobi]

Hope you like it. My 2010 is basically a 2011 with the older style headlight and fender. Its been rock solid reliable.

The yamaha part code is 4SR-14916-CW-00 NEEDLE. Some sites/dealers will list this as N3CC, but as long as the part number is correct you'll get the right needle.

 

[desertgasser300]

Hope you like it. My 2010 is basically a 2011 with the older style headlight and fender. Its been rock solid reliable.

The yamaha part code is 4SR-14916-CW-00 NEEDLE. Some sites/dealers will list this as N3CC, but as long as the part number is correct you'll get the right needle.

How does that needle compare to any of the jd needles for the gasser?

 

[Jakobi]

Somewhat similar to the JD Red. Still comparing a 2 taper (N3CW) to a 3 taper (JDs), so will never be an honest comparison.

Bit cleaner right off the bottom. People have reported the first taper as being a bit rich but that suits the engine well as its just rich enough to create good torque without breaking up. Just a matter of finding the right clip pos (which is why i suggested getting the half clip alternative too). Into the second taper it really leans out and continues to do so all the way to WOT. Result is a bottom end that will chugg up anything, a mid range that snaps like a 2T should, and a top end that keeps on pulling. In comparison I found the JD Red to be a bit bland and boring. Its middle taper keeps things richer and dulls out the transition.

JD Red: Lean -> Rich -> Lean
N3xx (yamaha/ktm) Rich -> Lean
NExx (suzi) Lean -> Rich -> Richer

 

[desertgasser300]

Somewhat similar to the JD Red. Still comparing a 2 taper (N3CW) to a 3 taper (JDs), so will never be an honest comparison.

Bit cleaner right off the bottom. People have reported the first taper as being a bit rich but that suits the engine well as its just rich enough to create good torque without breaking up. Just a matter of finding the right clip pos (which is why i suggested getting the half clip alternative too). Into the second taper it really leans out and continues to do so all the way to WOT. Result is a bottom end that will chugg up anything, a mid range that snaps like a 2T should, and a top end that keeps on pulling. In comparison I found the JD Red to be a bit bland and boring. Its middle taper keeps things richer and dulls out the transition.

JD Red: Lean -> Rich -> Lean
N3xx (yamaha/ktm) Rich -> Lean
NExx (suzi) Lean -> Rich -> Richer

Im running the jd red middle clip, with 38 pilot 178 main(just changed the main to this yesterday, was a 175) I can really feel the transition to the main. Slight hesitation, but nothing extreme. Might try a 40 pilot, just nervous it might be a little to lean. My riding has become more agressive over time and with the new 12' has really made me more confident to speed things up a bit.

Ordering the yama needle, RMATV lists it as an N3CW.

 

[Jakobi]

You may find the JD Red works better for you. I didn't spend a lot of time testing the JD Red. I did try 40 clip 3 178 though, and immediately concluded that it wasn't interested in experimenting further with it. It still had the transition into the top end. A 2T always will, but it just felt smoother and richer than I like.

For $10 the Yamaha needle is definitely worth having a play with. You'll see what I mean once you do. Its almost light switch transition, however the nature of the GG with a 2K3 ignition means that you can easily ride around well below the hit using the torque, and when you want to party its instant power on tap.

 

[adv rider]

11 xc250

I ordered the n3cw needle. I plan to try out 40 pilot, 178 main with the stock needle. Hopefully it will work well enough while i get some run time on the engine, hoping to try it out on monday.

I hope it won't be too difficult getting the jetting right, I am not real perceptive of changes/differences unless they are drastic. And i haven't ridden a 2 stroke offroad in 9 yrs- I guess the testing will begin , and i need to make sure i bring spare spark plugs so i am not left stranded.

 

[Jakobi]

With decent jetting you won't foul a plug mate. I carry 2 spares and in 7500kms on my engine I haven't once needed to swap one out.

If you're playing with the stock needle it has a rather rich end (towards WOT) so it'll happily work with a 175 main. Stock needle should be an N1EF. The difference between this and an N3xx is pretty drastic. Definitely noticable, and all for the better.

 

[adv rider]

11' xc250

Well I finally got ride, and the jetting seems about perfect I checked the plug 4x just to be sure it wasn't really lean. The plug was new so it will take some time to color. but it definately wasn't to rich. I rode for 1.2hrs and the electrode still had the new look, but not white or gray at all. some black around edge,but not completely.

This was at 40:1 motul 710, about 38-40 degrees.Not sure of elevation probably around 400-500 ft. very wet out, some snow flurries and fresh snow up top.

Had the needle at #3, 40/178. I had a slight hesitation just off idle. kind of like when you turn off choke to soon. so i think i will try 42 plt. or possibly shim needle a half clip position.
But otherwise it ran really good, i could leave the carb alone and be totally happy.

It's hard to say if main jet is ok, as where i ride i rarely get on the main jet. Initially had fuel leakage from overflow, try tapping carb did not stop, so i just rode it and it stopped shortly after. I figure something from tank possibly got in needle seat

Thank you Jakobi !! It would have taken me a long time to get the jetting right

 

[Jakobi]

No worries. You can either try a half a clip richer needle N3EW#3, shim it up half a clip, or if its just off idle a size up on pilot might cover it. I'd say it will if its cold out. Other option is to step up the diameter one size to an N3CH. Options options.

 

[adv rider]

jetting

Ok, I have been thinking about how my bike ran the other day . I am thinking that going to 42p, and also going to the 180m will be an improvement . Having very little exhaust smoke when running, and being a new engine- wondering if I should have ran a richer mix for the first tank?

Seems like it needs more pilot- it was idling ok , a/s at about 7/8-1 but...that off idle bog. Also since I didn't get much opportunity to open the throttle, and when I did it just didn't impress me much as I was expecting. I figure I can go up to 180 without problem. Also since I will be going to much more wide open event in a few weeks, it will be safer for my engine.

What is a normal amount of exhaust smoke? {motul 710 @ 40:1 } I stopped a few time to look at exhaust-and could not see any noticeable smoke, only smell.
How many miles can I expect out of a tank full , when ridden on the main often? The event I am going to has 30-35 mile laps.
Thanks

 

[Jakobi]

Don't jet for smoke or spooge. They aren't very good indicators and will vary during a ride depending on how you run the engine.

You won't have done any damage running the bike in with leaner jetting. Don't sweat that! If you have a bog off idle address that first. You're in on the air screw now, so thats the sign. Drop a 42 pilot in and try again. You may find yourself up around a 45 if its cold and depending on your conditions, preferences and fuels.

My bike smokes very little, but will heaps when cold, and will also puff a bit when clearing out if I've lugged it around. I only ever get an oily ring around the exhuast tip, but get loads of spooge drip from the header when the o-rings blow, and a steady flow from the PV vent.

 

[adv rider]

jetting

Took my second ride today. Jetting 42p, 180m, N3CW-#3. The temp today was about 30 deg warmer than the 1st time, so it's hard to compare that part.

I noticed first off that it smoked a lot more on warmup, and I needed to clear it out to ride it. But after that initial clean out it didn't need that again. I wasn't able to notice a diff with the airscrew settings, so I just left it at 1.5. I did have to turn out my idle screw to bring the idle down to reasonable, now it will idle about 30 sec the stall. That's about how I like it.

Felt good on the trail, good up top too. It didn't load up at all during the ride.So I think it was good stepping up the jetting. After I was done riding I looked at plug, it still looked pretty clean. I was surpised that 2.5 hrs of riding didn't color it. The threads were black , but the electrode still had a new raw metal look to it, but not like it was lean.

I am just going to leave it as is for the coming 100 mi event, and see how it does.

 

[TeamJames]

Needle Comparison

Can anyone help with PWK needle part #, the genuine Yamaha needle (N3CW) or 4SR-14916-CW-00 here in Oz retails for over $40, we have a Keihin dealer here but he can reference OME part numbers, is a CCK needle the same as a N3CW ?

 

[Jakobi]

James. The N3CW is OEM for Yamaha and KTM. Either dealer will help you out. KTM is cheaper than Yamaha here. Go figure. You can order them in from the states for around $10 + postage. Usually a few days back order. Or around $25 locally through ktm. About 3 weeks back order.

Where are you located?? I might have a spare. I'll sell it to you for $30! Hahaha!

 

[desertgasser300]

Crap, I ordered the wrong needle. I ordered an N3CK.