RB Swab or RB Mod? 2005 to 2011

[AZRickD]

I took the Gasser up to near Flagstaff, near what we call the "Airport Loop" at 7,000 for some trail maintenance and a bit of riding. Not much in the way of elevation changes that far south. Temps at 75F with seasonal monsoon rains dampening the volcanically-inspired soil.

I jetted it down to 168/38.

The map switch was quite noticable, with the Sun mode making it go through the revs in beastly fashion while the Rain mode gave it a feel of something like the pilot jet being a step too rich. Even without the map-switch difference, I think I'd jet it down to a 35. I think I might be able to go down to a 165 on the main but it wouldn't be mandatory.

My old bike was geared down with a 52T rear sprocket. It kind of fits my riding style making the clutch less of an issue. The 13/48 is somewhat tall down in Phoenix... it showed itself much more at 7,000 feet. I have a 12T counter sprocket that I will use (at least at altitude in the summer). Not sure about down south in the winter during our race season.

Like others, my bike has that plastic adapter on the boot. As well, it lacks a reed block spacer. I wonder what I might get if I installed the reed spacer (I already have the LTR PV cover)? Would that make a noticeable change in bottom, and what would the penalty on top be? Could I remove the plastic adapter on the boot or leave it in?

I would rather have more bottom if it didn't cause too much drop in top-end.

 

[Jim Cook]

I took the Gasser up to near Flagstaff, near what we call the "Airport Loop" at 7,000 for some trail maintenance and a bit of riding. Not much in the way of elevation changes that far south. Temps at 75F with seasonal monsoon rains dampening the volcanically-inspired soil.

I jetted it down to 168/38.

The map switch was quite noticable, with the Sun mode making it go through the revs in beastly fashion while the Rain mode gave it a feel of something like the pilot jet being a step too rich. Even without the map-switch difference, I think I'd jet it down to a 35. I think I might be able to go down to a 165 on the main but it wouldn't be mandatory.

My old bike was geared down with a 52T rear sprocket. It kind of fits my riding style making the clutch less of an issue. The 13/48 is somewhat tall down in Phoenix... it showed itself much more at 7,000 feet. I have a 12T counter sprocket that I will use (at least at altitude in the summer). Not sure about down south in the winter during our race season.

Like others, my bike has that plastic adapter on the boot. As well, it lacks a reed block spacer. I wonder what I might get if I installed the reed spacer (I already have the LTR PV cover)? Would that make a noticeable change in bottom, and what would the penalty on top be? Could I remove the plastic adapter on the boot or leave it in?

I would rather have more bottom if it didn't cause too much drop in top-end.

Unlike the oversized powervalve cover, which doesn't affect the power after the powervalve moves, the intake spacer will have an effect throughout the rev range; flattening out the top end power a bit compared to stock.

 

[AZRickD]

I'm a bit of a short-shifter, anyway. When the revs climb, so does my anxiety.

Keep the plastic boot ring or remove it? (I hope it is air tight).

It looks a little bit thicker than the reed block spacer.

 

[Jim Cook]

Just for the record:
I put my top end back together with the RB modded head and installed the CCK needle at 3rd groove. (I had been running my "2006 DE300 summer settings" on the 2011 EC250; with the 42 pilot, 175 main, and the N1EG with the clip in the #2 groove.)
The CCK may be an excellent jet needle for the 300 with the AS1 carb, but I lost the low end snap I had with the N1EG, and it spooged just as bad or worse, using the same 42 pilot and 175 main. (same conditions: 97F, 69% relative humidity, 500' to 3K' elevations)
After getting such a drastic change on the 2006 DE300 with the RB modded head, This wasn't the result I had hoped for with the modded head and new needle on the 2011 EC250.

In the next couple of days, I will first move the clip to the #2 position. If this doesn't give the result I'm looking for, I will probably abandon the Keihin single taper needles for now, and try one of the Yamaha needles that I got from Rocky Mountain ATV. (I got 3 Yamaha needles and one Suzuki needle.) Most likely the N3CW, first.

One thing for sure, like you fellows told me, the AS2 jets leaner than the AS1 carb.

The last time I was in Idaho, riding the 2006 DE300 aat 6K' to 10K', when I moved the needle clip to accommodate the higher elevations, my bike ran hot (lean). I ended up with the clip back in the second groove, the same 42 pilot, and the 172 main. The only time I have ever jetted a Gasser leaner was for a trip to the Jemez Mtns in NM. We were riding from 9500' to 13K'.
That time (summer temps), I ran a 40 pilot and a 170 main in the AS1 carb on a 2004 EC300.

Good Riding and Jetting!
Jim

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