Needle Testing

[Wbdisco]

Having read a bluzillion jetting posts I decided to run a test on my bike. Quick and to the point.
2011 ec250
AS2 36mm
6.5 slide
55f
1800? elevation

JD blue #3 38/170 AS 1-1/2
Seemed blubbery down low but torquey definitely rideable, clean throughout WOT. Idle was decent at about 1100rpm

NEDW #3 40/175 AS 1-1/4
Bottom end was rowdy, not overly lean but crisp and definitely not blubbery. Mid to WOT was so rich it seemed to want to drown out the bike. I bumped the pilot up to a 40 since this needle is a few steps leaner than the blue. Saw in some other posts that it might be a good starting point. The 175 might have been overkill but I didn?t have any smaller mains but a 165,168, and 170. They seemed a little lean to begin with.

NEDW #3 40/170 AS 1-1/4
Same bottom, but mid to WOT was still super rich. I was really thinking I would notice some difference but it was minor. So is going to a 168 the next step or moving clip positions? Will moving the clip mess up my awesome bottom end?

Appreciate the help.

[webmaster]

Originally Posted by Wbdisco

Having read a bluzillion jetting posts I decided to run a test on my bike. Quick and to the point.
2011 ec250
AS2 36mm
6.5 slide
55f
1800? elevation

JD blue #3 38/170 AS 1-1/2
Seemed blubbery down low but torquey definitely rideable, clean throughout WOT. Idle was decent at about 1100rpm

NEDW #3 40/175 AS 1-1/4
Bottom end was rowdy, not overly lean but crisp and definitely not blubbery. Mid to WOT was so rich it seemed to want to drown out the bike. I bumped the pilot up to a 40 since this needle is a few steps leaner than the blue. Saw in some other posts that it might be a good starting point. The 175 might have been overkill but I didn?t have any smaller mains but a 165,168, and 170. They seemed a little lean to begin with.

NEDW #3 40/170 AS 1-1/4
Same bottom, but mid to WOT was still super rich. I was really thinking I would notice some difference but it was minor. So is going to a 168 the next step or moving clip positions? Will moving the clip mess up my awesome bottom end?

Appreciate the help.

Where are you located? I believe fuel has a slightly different specific gravity in places like australia, NZ etc.

What mixture ratio? I used 32:1 for longer life and better ring seal.

Also which pipe are you using? (I loved the Doma - but would gear completely differently from using a FMF Gnarly).

You need to get more fuel and air going through the pilot circuit on this carb... With the 38-40 pilot and 1 1/4 air screw setting - you will need more fuel/air at idle - so you end up turning up the idle screw to compensate.

You can tell the carb is in this state (aka "pulling over") by the fact that the air screw seems to have little effect - because too much fuel/air is coming through needle jet/slide (relatively speaking).

For your altitude, I would go with a 42 pilot and air screw setting at 2 1/4 turns out to start Turn out idle screw for initial setting and then reset for good idle with pilot and air screw setting above. It is critical when changing to a "good needle" to back out the idle screw and reset it.. And don't use standard thinking of 1.5 turns out on airscrew - use more on this carb - up to 2.5 turns out.

RB-Designs has a carb mod that fixes the lack of low end sensitivity in this carb. Ron may have retired by now - and, at one time, he didn't want to deal with foreign shipping... So I would e-mail him first to check...

I have seen others use a stic metering block for a "fix" - not sure how it compares to RB-Designs Carb Mods.

Since this carb does have issue with idle/pilot circuit not having enough sensitivity - I would start with needle at one clip up from middle position (leaner from middle position). The 6.5 slide is good and preferable to the 7.

The needle clip setting will have no effect at WOT. You should be "all on the main" at that point.

Make sure your air filter is cleaned and only lightly oiled for all jetting tests.

This is where I would start based on my experience - we rode in tight woods so having clean bottom end with smooth transition from idle to mid was paramount. This gives a less exciting "yank" compared to the dorked stock jetting - but the smooth transition is less fatigue-ing and puts the ground to the power much better.

I don't own a gasgas now - but my bike was used for LT-Racing jetting kit that was sold years ago... It used a ddk needle from sudco (keihin importer in USA).

Note that an older carb body can have a nozzle (fixed needle jet) that is worn into an oval. This will make it very hard to jet. At one point - Ron @ RB-Designs was machining up a new one and inserting it into the carb body... If the nozzle is worn on the carb body - it will typically need to be replaced.

That's all I can think of and probably way too much detail... ;-)

jeff

[Wbdisco]

I?m in southeast Tennessee. Actually my air screw worked fine. I did get lean hanging idle when turned out. I believe I found the right setting for it. I thought I read the 36mm would need to be jetted leaner due to the increased signature. I have a 42p on order to try later, but the 40 seemed good to me. I definitely will try a lower main jet. I don?t feel like the bottom end was suffering from skimpy fuel delivery.

[(F5)]

When you have it right, you twist the rotating tube towards you and it should go "WAA- AAh", and when you close it, it should go 'A-DingNingDing. Followed by of course "WAA- AAh".

Simples.

[Wbdisco]

lol, never heard it explained any better