CEJ vs DGH

[IcutMetl]

What is the difference between the two needles and what will it mean to me if both are run on the middle clip? I just had my top end redone and am trying to sharpen the off-idle throttle response and power.

I have about 3/4 tank of gas thru it now, and want to start playing with my jetting now that it's about broken in.

It has a 67.5 Wiseco piston, thin head gasket @ 195+/- psi compression, 50/50 CAM2 110 octane and 92-94 pump, midrange porting, 38mm PJ, Boyesen RAD valve, airbox & UNI- vented lid, 40:1 & Super Techniplate, FMF Fatty.

I started out with a 175 main, 60 pilot, CEJ on middle clip. Starts on 1-3 kicks, sometimes w/o choke, and will idle for 15min plus, also clears out pretty good.

As the motor breaks in more, I'm starting to feel like I'll have to bring the main back one step, and 1 or two steps on the pilot as well. I've heard the DGH needle is a good change; what will that mean for me?

Thanks for the help!

[1promodfan]

I tried the CEJ with my new setup and it made great mid-range response, it just still "sputtered" on the bottom. I now have a DGK needle in mine, and so far I love it.

I've never tried the DGH, but I know a lot of guys do. Thats what ESR recommended for me, but I guess with the atmosphere conditions here, it just wouldn't work.

[C-LEIGH RACING]

Atmosphere, thats what its all about when it comes to jetting a 2 stroke.

I dont have the needle chart, but the DGH is not a fat needle & will provide more fuel from mid to full throttle.

If you have a stumble off idle & you have the carb set so it will idle real well, could be a lean stumble, dead spot when the slide pops open.
If it has a spudder, like when you stab it just before the engine starts to pull, the carb is rich but that dont normaly happen if you have a good idle.

For a 250R engine to have a real good idle, that means the carbs got to be lean enough to support a good idle & in turn will be lean when you stab the throttle.
2 strokes dont like a lean spot when you stab the throttle, what happens to a 2 stroke when you run it to lean, yep you got it, seizure.
2 stroke carbs dont have an acelerator pump like a 4 poke carb, so its got to be rich enough at real low rpms so the engine will have fuel to run on.

This is the very reason my 2 strokes dont idle.
When you chop the throttle on one of them, the engine is off untill you give it some more gas & when it is opened back up, theres a good amount of fuel built up to mix with the incomming air from the slide opening.
Neil

[LONG-ROD]

Neil, I dont get it my r idle's all day. I run a dgh needle 2nd, 175 main and 48 piolt. sea level, no lid and a uni filter. should your slide shut all the way? maybe i have mine idleing on the throttle cable.

[86 Quad R]

what elevation are you at longrod? i'm thinking you pilot is phat and you've got it idle'd up to keep it running.

i like to set the pilot just so that it makes very lil difference when adjusting the screw with the idle set to where it will almost always go dead when the clutch is pull and coasting to a stop.

mind you, it takes a bit of tinkering to get there with it. :cool:

[IcutMetl]

I messed with it a little more today and it was giving me fits. I have had the best luck (not to say that it's 100% right) with a 175 main. Tried a 178 and 172. Have a 60 pilot in there right now; also tried a 58 & 62. Went from a CEJ middle clip to a DGH middle clip. Off idle was ok, but not what I would think it should be- bogs a bit. Mainly mid & mid to top it sputtered & coughed no matter what needle, needle position, or main I tried. Airscrew was 1.5-2 turns out. Tried moving the clip up on both needles to lean it out, but I gave up on it for the evening.

It starts fine, idles fine too. I got frustrated and decided to give it a break for a day or so.

[LONG-ROD]

Is your coil wire clean and is your slide opening all the way at full throttle. if either is not right she will never run smooth from the needle to full throttle. 86 quad R I am at sea level. you think I am fat. she does make some smoke if I putt her around for a while.

[IcutMetl]

Yeah, throttle valve is fine- I haven't touched the coil wire, but it looks to be in the same condition as before I touched the engine.

Before my rebuild, there was an overbore Wiseco piston, no porting, clamp-on K&N, same carb & intake, 160main, 55 pilot, CEJ needle middle notch, airscrew 2 turns out. But it had a hi-rev pipe, so powerband was non-existant anywhere but top end anyways.

When I started breaking it in the other day I started with the same needle & position, airscrew position, but changed pilot to 60, and 175 main. Airbox with holes in lid. Seemed to run fine, but I wasn't laying into it during break-in. Towards the end of the tank, I started to pick up on little sputters here and there, and a slight lack off the bottom- which is what I tried to fix yesterday and ended up worse off than before.

[machwon]

Icutmetl, your pilot is too big for sure and the jetting will likely end up where you started at. I'd drop your pilot to a 52 to start.

[C-LEIGH RACING]

Thats what I was thinking, that 60 pilot is way to big for Ohio areas.
Beleave it or not, when you go that big on a pilot, it will have some effect on the mid throttle responce. If its bogging, it cant help but bog with that much fuel up through the idle curcits.

Any time you turn the brass air screw out more than 3 to 5 turns, more than likely the pilot is to big, that is if your one that wants an idle.
Neil

[IcutMetl]

Awesome; thanks for the help guys...that's kind of what I suspected too. I'm up in Cleveland right now- I'll stop by Carb Parts Warehouse and pick up some smaller pilot jets.

For some odd reason, when I ordered pilots out of rocky mountain, I only bought a 58, 60, and bigger. There was a 55 in it when I first bought the bike; I just thought I'd always have to go bigger.

[C-LEIGH RACING]

Last year at the TT race at Ashtabula, we had a 48 pilot & the air screw out 1 1/2 turns on a 42 mil A/S & 330 jug.
Neil

[IcutMetl]

I just bought a 50 and a 52. I think what I'm going to try next is my original CEJ needle on middle clip (where it started), the 175 main, 2 turns out on mixture screw, and the 50 pilot.

That way, the only part of the equation that's different from the day I was breaking it in is a pilot thats considerably different. I should be able to trim that in.

[fulltiltrider]

cej will be leaner at 1/2 to 3/4 throttle than a dgh, richer at the 1/4 to 1/2 and slightly leaner at 1/8th throttle. Love the cej for its responce in the 1/2 to 3/4 range.

[IcutMetl]

This is the color of my plug with a 175 main, 52 pilot, and CEJ needle on bottom notch- airscrew 1.5-2 turns out.

I switched to the DGH needle; left everything else the same, and ended up a clip up from the middle. It was a crap shoot which way was better. I went up to a 178 main, but then I had to lean the needle way out to get it to come close to pulling right.

It's still lacking in the mid-top.

I will tell you that it has absolutely no bottom end. I don't expect it to or want it to be a tractor, but it takes a lot of clutching to have it come alive. It bogs a lot, and it's transition into 1/4=1/2 throttle range is not a real charm. I figured it would be better with the Fatty pipe.

Could I possibly need to go leaner on the pilot again? It will idle just fine, and hold a nice low idle when you let it sit, but when you stop from riding or giving it gas, it will have a fast idle that will taper off to a nice low idle. If that makes sense.

Thanks for all the help!

[rustyATV]

Looks a bit rich.

Here are a couple of tuning aids:

http://img.photobucket.com/albums/v11/hoppy/calchart.gif

Pilot jet is mainly for idle, but can fine tune the just off-idle mixture as well. For off-idle range throttle response, what you want to focus on is the straight diameter (the last of the three letters). Moving the clip up and down doesn't really affect the off-idle mixture

http://img.photobucket.com/albums/v11/hoppy/pj_34_39_jn.gif

A pilot in the 50's seems excessive to me, I think I'm running a 42. Of course, I also have a woods setup and it tends to run richer in the low range.