RB Swab or RB Mod? 2005 to 2011

[AZRickD]

A special situation.

Having taken possession of adv_rider's 2011 EC250 Race, I am (this morning), doing a squish measurement and such.

My '05 had both a the squish (about 1.05 mm) and the carb mod (old Air Striker 1) completed with excellent and good results respectively.

I am hoping that my old modded head will give me a good squish on the 2011 and then I can send in the stocker into RB to make me a head that is potent at 10,000 feet if I ever visit Colorado. I told RB that my riding in Arizona is usually no lower than 2,000 feet and often at 3,500 for a few races, and even at 6,000 and 9,000 when heading to Flagstaff in the summer. Temps are around 50F in the winter in Phoenix, 95F in the summer (at sun up) at around 85F in Flagstaff at mid-day. The best pump gas we get in Arizona is 91 octane.

So, the head issue is fairly simple. BTW, my modded '05 with about 60 hours on the top-end compression tested out to be about 25 PSI higher than the stock 2011 with 13 hours. More later.

The carby, on the other hand (SmartCarb and Lectron aside) -- I have been told that the Air Striker 2 is a better carb than the AS1. Fine, as it goes. I am wondering whether I should keep the un-modded AS2, swap my modded AS1, or get the AS2 modded by RB.

Thoughts?

Rick

[AZRickD]

Measured the stock 2011 head -- Avg = 2.12 mm

Next up is the RB-modded 2005 head on the 2011 jug.

---

Interesting...

The modded '05 head when placed on the 2011 jug measures ~1.33 mm

To check, I re-measured the '05 head on the '05 jug --> .92 mm

On my last top-end on the '05 I used a Vertex piston and a single stack for the base gasket (probably .5mm). I can't recall what was on when I did the original squish a few years ago.

[roverhybrids]

I got my AS2 moded And I think I may be unhappy with RB cutting the slide(originally a #7) i bought another stock #7 notched slide and it almost got rid of the 1/8-1/4 throttle lean bog(JD blue needle).
I've tried 3 different needle and before I swapped the slide back to a stock I had a mid throttle bog.
I'm not saying the RB mod can't be made to work, I just haven't figured it out yet

[forgiven]

I believe he cuts them to a 6

[AZRickD]

The question now is, what base gaskets do I have in there?

I checked with a light and magnifying glass and I can't tell for sure. I may have to do a jug-ectomy.

If it is the common combo of .5mm + .3mm then, as GMP advised me, I could take out the .3mm gasket and I would be at a golden 1.03mm of squishie.

I am not the type to go in and yank the jug (normally), but since the bike is already partially dissembled, what the heck? As long as I can avoid messing up the PV system.

[Jakobi]

1.3mm of squish will also run just fine. Port timing will give you a bit more up top, as will the slightly lower compression. Note: on my 250 I'm running a modified head, 0.6mm of base gasket, and 1.35mm squish height. Remember if you take the cylinder off you'll have to replace the base gasket too. And well, torn down that far you might as well re ring it too! hahah..

[AZRickD]

Well, there's no reason not to give it a go, I suppose. The motor ran nicely with the stock head, although it was jetted a bit rich (coming from Seattle).

Jakobi has brought out The Lazy in me.

Is there anything I should snag from the RB-Modded Air Striker-1 carb to put in the Air Striker-2 carb? Slide? Needle jet? Needle?

What's a good starting point for jetting the AS2 at Phoenix's 2,000 feet and 95F sunrise temps? I've yet to look at the 2011's carb yet (frickin' hot in my garage).

[Jakobi]

Check the carb first and have a look whats in there. It might even be close with current head.

[AZRickD]

Yer gonna make me werk for this.

[Jakobi]

*nods*

I can't remember what adv rider ended up with maybe 42/45 N3EW#1/N3CW#2 and I think a 180 main. Very much on par with what a YZ250 would be running too. It shouldn't be far off.