2K2 vs 2K3

[Fred1956]

I have both setups but want to know what to expect. I am running the 2K2 w/7 oz (advertised) weight that came on the bike (2006 EC250) and after getting RB carb and head mod done I'm sorting out jetting and power. I read in a post today that the 2K3 has more inertia than a 2K2 w/12 oz, WOW. I rode for the greatest length of time (about 30 miles) that I've had a chance to yesterday with kids' stuff, work etc and noticed a quick loss of power on long semi steep uphills. I used to pull them in 2nd and struggle a little and now it seems worse. I'm also having issues stalling in corner, had to restart several time which has been not necessary in the past. The plug looks very good, light tannish definitely not to rich or lean but the bike seems to fall off the power very quickly and doesn't respond to clutch slip very well, at one point I let it pull down and then tried to downshift but it actually caused me to have to stop and start over again. I also am trying to learn to run the bike 1 gear higher and be smooth instead of ripping all the time. (Tight single track hurts when you're richocheting off trees). But I've lost a lot of confidence in trying to cross downed logs etc because the front wheel doesn't want to loft easily. Will the 2K3 help or am I missing something else. BTW I come from MX and this is a whole new riding style for me.

 

[dank]

have you considered different gearing? it would let you run a little higher rpm for the same speed, and it would maybe make log hops a little easier as it makes it easier to get the tire off the ground, but requires a little more rpm to keep it up there. like say a 13 tooth front sprocket and a 51 rear? thats what i run. it makes running slow through technical stuff easier and its not like your going to run out of gears, there's 6 of them. and it might be easier than switching your ignition stuff.

 

[bchatt]

The symptoms you describe sound to me like you are running a little lean. I have found "unexpected" stalling and a reluctance to "get on the pipe" or as you describe " not responding to clutch slip" can generally be helped by raising the needle a clip. Worth a try. My bike has the 2k3 and I find it allows great mix of tractability and revvability.

 

[Fred1956]

Thanks for the suggestions:
dank- 13-51 is the gearing I swithced to. I did have a 48 on the back. Yes it's better but...
bchatt- lean? I've been thinking fat but I could try to move needle up...

FWIW jetting is as follows (from memory as I'm at work)
altitude 500-1200 ft
178 main
CEK needle in middle groove
42 pilot (I was going to go back to a 40 like before the mods)
RB airscrew 2.5 turns out.
#7 slide
I was concerned after the airscrew got that far out about it vibrating out. I followed the instructions that came with the carb mod and after much throttle roll on and adjusting both directions this was the best at the low end but....My plane was to drop to a 40 pilot and turn the airscrew back in and start from scratch.
My theory/wondering- The carb mod cleans up & intensifies the air flow at low throttle openings. Could that be causing a rich condition (or lean)?
Again- not fouling plugs nor burning them up. To look at the plug I'd say jetting was dang close, thus my ?? about ignition.

Thanks again

 

[gasser]

Just thinking out loud here is there any possibility that the power valve isn't working properly? It's not uncommon for it to get out of whack if you move the actuation rod very much during engine rebuild (cylinder removal).

 

[Fred1956]

Gasser-I haven't checked that but will when I get back to the bike.

Update- Last nite I got about 30 min. to fool with it, I dropped the clip to the 4th groove and it seemed worse, so I moved it to the 2nd groove and it felt better. Still not 'right' but better.

Got kid events next 3 nights so it'll be a day or two before I can check power valve. I may go ahead and drop bowl and go to 40 pilot since dropping the needle seemed to help.

Still didn't get much opinion on original question, is the 2K3 hotter or just heavier?

 

[stainlesscycle]

Still didn't get much opinion on original question, is the 2K3 hotter or just heavier?

2k3 is heavier.

 

[Skidad]

A 2K2 flywheel is 29oz and a 2K3 flywheel is 30.5oz. So 1.5oz heavier from notes I have collected.

However it's mass is carried further from the crank which has a pronounced effect apparantly.

2K3 has much higher light output also, more than double the 2K2.

 

[GMP]

The symptoms you describe sound to me like you are running a little lean.

I agree with this as well, although I cannot offer any meaninful jetting for the RB modded carb as I do not have one. I do know that on a 250 with a stock carb the CEK can be a bit lean. I tried the C series on my '03 and it was flat on torque as you describe and liked the richer D series and newer LTR needles better. A light tan plug on a GG 2-stroke is too lean, from my experience err on the rich side for best torque and power delivery. What needle works awesome on a stock 250 is a JD Blue needle from the generic PWK38 jetting kit. Its similar to a DDK but with added tapers so it may work for you with the RB carb.

 

[jefgil123]

I find that the RB head mod "seemed" to make the bike more prone to stalling,
just a little (maybe).

I like the richer CCK needle....I tried the CEK and it was too lean. 42 pilot
#7 slide, 180 main

I like the results of taking out the power valve (2) shims behind the
spring I did put a slower turning G2 throttle on it to control it.
Seems to come on the pipe better right off the bottom, for lofting the
front end.

I like the heavier ignition, I have tried three set-ups, 2K2, 2k2 with 10 oz.
(very nice) and 2K3 maybe a bit too heavy....

Jeff XC300 2001