Read my plug?

[IcutMetl]

The following is what my B8ES looked like after about a tank or two of gas; mixed riding, and a pretty full throttle shutdown. Had the best luck with a 175 main, experimented with a 48 then 50 pilot, and started with DDJ needle on middle clip. Airscrew 1.5-1.75 out. Have been trying to get rid of a low end stumble. It runs good, but needs fine tuning

This is on a worked 38a/s carb, 67.5 mm midrange ported stock cylinder, 195psi+ compression, 50/50 premium & 110, 40:1 Super Techniplate, RAD Valve, open airbox, FMF pipe.

To me, this appears overly rich. Neither the insulator or electrode was oily, but the bottom of the plug was. It didn't foul out, and will idle relatively good.

[IcutMetl]

Still trying to get rid of that slight stumble off the bottom, I tried going from a 50 pilot to a 52. Didn't seem to affect it one way or another. Changed to a new B8ES gapped at .018-.020". I lowered the clip on the DDJ one notch (4th) and took it for a spin- negative effect. Put the clip on 2nd notch, definite improvement; more snap and response all around. Raised clip one more notch to #1, and slightly better yet. Seemed to have improved the pull all over.

Came back today and ran that setup for about 1/3 tank worth at mixed RPM's, but really cranking into it for the last bit, including a full 6th gear pull down the road.

Below is what the plug looked like; this appears to me to be well on the lean side. For craps and grins, I installed a CEG needle on the middle clip and blasted around the yard and down the road then back. Didn't seem to be enough time; didn't appear to change the color much; if anything it was a hair darker...maybe. It also seemed to sign off more in the last 1/4 worth of throttle...like it needed more fuel.

[machwon]

Yes, I agree too rich Icutmetl in the first pic, the second looks alot closer still a tad rich. I usually run a DGH needle on the middle notch and as low as a 42 pilot. The main might go as low as 172 with an ESR pipe, but yours may go lower to like 168. What number is under the throttle slide? Usually the A/S have a 6.

[IcutMetl]

Thanks for your reply. The slide is a #7, but I hear a lot of people are using the #6. Is that helping/hurting me?

The DGH on 3rd clip is where I had the best luck on my 38PJ; sold that carb with the jets in it. I have DGH and CEL needles coming, as well as 42 and 45 pilots- expect them to arrive tomorrow. Will start back with DGH on middle clip and go from there, then play with pilot, then possibly main if needed. Still don't understand why my choke will cause a slight idle increase instead of an instant stall, but whatever.

My dilemma is that this is the only 250R I've ever ridden or have the opportunity to ride and don't have much to compare it to, so I'm just going by sound, feel, and the ol' butt dyno. My riding buddy has a DMC piped stock Banshee, but that's an entirely different animal. I can say that this is the best running 2-stroke I've ever owned, mainly because I understand them a lot better now, and tuning help from you guys.

Machwon; this is the top end you did for me, and it keeps getting better the more I ride and the finer I tune it. It feels like I'm about 80% of the way to a perfect state of tune...very happy so far.

[machwon]

The slide won't change a whole lot, a little better response with a a 7. The 7 would want a smaller pilot jet over a 6 slide with everything else the same. It sounds like the DGH needle will make everything right. Glad to hear its running good. Keep us updated on your progress.

[buford]

try a DEJ in the middle clip position. If you are running your DDJ in the top clip, you need a leaner needle in the midrange and the next leaner is the DEJ. It will either be the 4th or 3rd position on this needle. The CEG will probably be too lean. 52 pilot and 172-175 main should be about right.

[hondamancbr03]

I had the same bottom end stumble on my 350PV running a 38A/S and 215psi.......Race gas only. I started with the DDJ and after studying the needle chart i went to the DEK middle clip and 172 main, 52 pilot and i can't tell you how perfect the bike runs.

You want a needle that works best in the middle position.....