Eric- CR250 cylinder question

[147leeman]

Eric, I have an 01 CR250 where I race outdoor mx. I have the dilemma where I race a few wide open fast tracks and also tight sx style tracks that are stop and go. Here is my question:

I do like my topend 01 cylinder for the fast, momentum filled tracks, but I want a better low end-all around powerband for the sx tracks...

can I buy a 96 CR250 cylinder (which uses a domed piston) and install this with the 01 head, studs, powervalve, and flat top piston from my current set-up or is this more involved than this? I seem to remember something about the center powervalve not being correct? Gearing and other bolt ons aren't helping the change between the fast courses to the sx courses and I'd like 2 different set ups.

Or is there a better solution to this?

Thanks for all your help, your motors have always been an improvement in the direction I've needed.

 

[Buzz Bomb]

Why not have Eric port it for more low end, and keep the top end it has already. I'm sure he could hook you up, and you won't have to go through the trouble of changing cylinders and heads all the time...

 

[nomsquid]

I'll chime in on this, since I just dyno'd my '01 CR250 with its Eric Gorr cylinder. After a bunch of fiddling with jets, the final results came to 45hp & 32 ft-lb. at the rear wheel, peaking at 6500ish RPM. The bike setup is:

Gorr-ported 265 big-bore cylinder
370 main/30 pilot/stock needle (still need to play with needle clip position)
32:1 VP C12 & Maxima Castor 927
Boyesen reed petals in stock cage
Stock pipe w/ FMF TC2 silencer

The bike's a supermotard, and the track I usually race on is very tight (don't get out of 4th on the straight), so the powerband is perfect for my situation.

Rather than playing mix and match with OEM Honda items, get a ported cylinder from Eric. Much easier, probably cheaper, and comes highly recommended :thumb: (and not just by me!)

 

[marcusgunby]

wow 45hp at 6500rpm is alot considering how low its revving.

 

[147leeman]

nomsquid, I was thinking about a big bore kit...could you post the dyno results? and how what was it ported for? those jetting specs will really help when/if I go this way!

 

[nomsquid]

I didn't get a printout unfortunately (printer problems or something)...basically it was a nice smooth curve peaking between 6500 and 7000 RPM, and dropping off after that. So smooth actually, that the dyno operator started checking to make sure the powervalve was working. The porting was for low to midrange power...I don't have the port-time measurements or anything though. That's Eric's domain ;)

Jetting - we basically leaned things out until the plug was a nice tan color. The pilot and needle are still a bit too rich, but we'll be tinkering with those later on. We're at sea-level, and it was about 75 deg/90% humidity when we were testing.

 

[147leeman]

Overall you sound pleased with the results? I may be looking for more top end than your configuration, but the added displacement and port work may be what I need. Thanks

 

[MXTex]

Several bikes ago I had a 94CR250. I decided to have Eric port the cylinder for low to mid power. I got exactly what I asked for but it was not what I needed for MX. After I had that cylinder ported, I bailed off that bike so many times I lost count. The motor was simply too radical off the bottom for me on an MX track. I still send my cylinders to Eric but now I always ask for more better everywhere porting. Just remember, he'll give you what you ask for so make darn sure that's what you need or you may end up in a body cast. :scream:

 

[premeir]

I was actually gonna post about that, I see Eric sell's the ported cylinders outright, I think even refurbished ones. My problem is I'm coming off a long layoff, eight years, and I always rode kx 250's. I just don't have my timing and corner speed back yet, and I'm in it so far up the revs to get it moving that the 01 is more like an exsplosion from corner to corner. Hard and tiring to work with on these tight sandy Florida tracks. I'm more a rider that will square the corners now, and with my advanced age of 31 I'd be happier with something a little broader, less work. I've made up my mind I wasn't going to do too much more as I'm just waiting to decide between an 03 KX, or CR. I've tried everything I didn't get the stock pipe with my bike, and I think the PC pipe compounds my problem. Any advice on this? Which porting, or just buy the entire cylinder? If it's worthwhile I'd like to have Eric help me, and maybe wait till next year for an 03, it's just that I have an opportunity to unload this thing now and get a new one in about a month.

 

[MXTex]

Premier,
My advice would be to call Eric. He can tailor your porting just for you. He'll also change or modify your porting if you don't like. On another cylinder I had ported, I wanted more low end after I got it back from Eric. We talked and I sent it back for some tweeking. He tweeked it and got it just where I wanted it. And in this case, did it free of charge. This cylinder porting is kind of like tennis racquet string tension selection. Everybody has their individual pet peeves. Eric can accomodate. In my opinion, buying another complete cylinder would be neat but extravagant.

Have fun,

Jim

 

[Calvin]

Premier,
Try a stock pipe, the power will be smooth and nice compared to the PC pipe.

 

[mxneagle]

I have an '01 and with some pretty basic work was able to fill in the bottom end nicely without really hurting the top end. 0.008 milled from the head, cometic thin (0.012") base gasket, v-force reed block, 6mm power valve spacer, cut slide 1mm different needle, main & pilot