Ok so I have read about the "gross mismatch" between the cylinder and the cases. So how do I go about stuffing the cases? Or who can do it for me?

I've owned (5) gen 3 cr250's & didn't feel the need to do any mods to the cases.   The case reed motor responds very good to changing the port timing & fixing the excessive squish volume.  I had PC do the cyl. & head on my 03 with very good results.  On 100% race gas with a fresh topend it pulls like a freight train & has a wide useable powerband.    Just my $.02

Ok thanks

I have no interest in owning another gen3 again, the engine does not work for me,  and I've tried to find info on what mods people do to bring the power similar to a 96'ish cr250 and I've not had any luck

MrBlahh, on 25 May 2012 - 11:42 AM, said:

See my "New '07 CR250" thread. For less than $100, I made the engine in my '07 run better than the engine in my '95.

What's wrong with the newer motors?? I don't know what it is, but I've always loooved the 90's 250 motors, especially my 98.
Extremely reliable, but most importantly all of the electronics in the newer bikes, I don't particularly care for. Decreases reliability a bit, just like how most newer cars are more CPU than motor...and my 95 5.7 350 Chevy truck is super easy and pure to work on, and most importantly, diagnose!

I dunno, definitely a bit old school with my mechanical preferences I guess.

Edited by BlackCR25098, 26 May 2012 - 05:49 PM.

Yea points are so reliable...

BlackCR25098, on 26 May 2012 - 05:48 PM, said:

the 90's and the 98 were great motors,  the gen3 2002+ went to a different engine design, some like them some like me dont

CamP, on 25 May 2012 - 12:35 PM, said:

your mods require race gas, not something I will go to with as much riding as we do.   The carb swap is a required mod,  I suppose you could machine the bottom of the cylinder and match the head so you dont have to run race gas.  

someone posted a "what's wrong with this engine" with all the specific port design/specs compared to other bikes on here or atm I forget,  but it's a pretty nasty list of bad design choices.

Everyone I've talked to said case stuffing helped bottom end a ton, with the airstriker bringing the engine close to the one it replaced,  but nobody has done a howto

mismatch at the case/cyl is not hurting anything

305TID, on 24 May 2012 - 05:48 PM, said:

MrBlahh, on 27 May 2012 - 05:17 AM, said:

I run 100LL which is only $4.75/gal around here. I don't run pump gas in any of my 2-strokes. Even the ones that can tolerate it. The reason is all it takes is one batch of fuel from a station that has 87 octane marked as 93 octane and your engine is toast. Been there, done that. Leaded fuel also makes a 2-stroke engine last longer. For a few bucks, you could machine the head for pump gas, if you really wanted to use it.

Honda already reduced the volume of the 05-07 cases, so I don't think additional stuffing is necessary on those models.

Edited by CamP, 27 May 2012 - 07:57 AM.

MrBlahh, on 27 May 2012 - 05:17 AM, said:

There is a great thread somewhere with a pretty good case stuffing how to, i have stuffed the cases on my 2006 CR250, filled the transfer hooks, 2 piece head with corrected squish/shape/volume, 38 PWK, Boyesen reeds in stock cage, modded power valve stopper, DEP exhaust system, now, this engine can be ridden on the throttle from lower rpm's than stock, with a nice smooth pull, no 'big' hit, and into a still screaming top end. I had some head to head runs with a pretty sorted CR265, the owner of that guaranteed me that he would pull on me, he is a better rider than me, carrying better speed through the turns, and i kept on his rear wheel on every occasion on Saturday.......doesnt say a great deal, but he was non too pleased at my home built 250 running with his $2000 265 engine.

CamP, on 27 May 2012 - 07:52 AM, said:

I would have killed to have anyone tell me this or read this in one of the FUEL threads, but where the hell do you get 100LL??? I am running 93 pump gas and want the best of the best, but when I try to ask people tell me the opposite of what you just said.

The funny thing is, I remember when I first bought this 98 5 years ago, I put 87 in it on accident, but it was more than fine apparently.

I am interested in running the better gas, if you'd tell me where I can get it. I also have a ethanol free station down the road from me with 93.

100LL is Aviation Fuel or better known as Avgas
Just put in your Zip code to find the nearest location. The small FBO's (Fixed Base Operations) are the easiest to work with and even better if you know someone that works at one. Camp is fortunate, I just paid $6.85/Gal today
http://www.airnav.com/fuel/local.html

Edited by AXAxiom, 27 May 2012 - 01:27 PM.

all my bikes will run on 87,  not about to do anything that would change that

AXAxiom, on 27 May 2012 - 01:20 PM, said:

Yea they only sell AVgas near me at all the local city and county airports. F that...Much as I ride, that'd be a huuuge bill to add to my already too big riding bill, since our 3 tracks are each an hour away. My bike loves 93 with klotz @ 32:1 just fine, and I also add some Lucas ethanol treatment to the mix for anything that sits in the carb over a couple weeks.

Going to a new one called 886 in MS tmrw, bout 2 hours away. Stoked.

Edited by BlackCR25098, 27 May 2012 - 09:39 PM.

BlackCR25098, on 27 May 2012 - 09:38 PM, said:

I don't know where you live in TN, but you can get 100LL as cheap as $4.32/gal in your state. It may be even cheaper at the 100's of private air strip in your state. http://www.airnav.co...ong?type=1#usTN

Edited by CamP, 27 May 2012 - 09:50 PM.

MrBlahh, on 25 May 2012 - 11:42 AM, said:

The motors in the early to mid 90's CR250's are very good bone stock.  I've owned a 93 & good friend a 96 with the 96 having cyl. mods.  Aso ridden an 05 & 07 set up for enduro & trail type of riding (hairscrambles).   The 05 motor had the PC mods but was running the optional head cut for pump gas.  The 07 had a lower comp. head with an fmf gnarly exhaust.  In comparison they were running very similar to the 90's motors on pump gas with a wide powerband with good torque thru out the r's...

I tried a gnarley, fww, and pwk, we  went back to a 2000 with a 96 cylinder, gnarly, and fww

I'm over the gen3 frame, for the same money now there's a few other choices

If 87 octane will run in your engine with zero pinging, there is NO REASON to run anything else.
Though, increasing the compression will result in more power, and some prefer that gain ... so to each his own.

I have not found the Gen 3 case reed motears to be lacking on any real level.
The character and exhaust note is different, sure, but they are still a 249cc engine, and competitive.
Durn fast enough to pull most people around just fine.

If maximizing torque and minimizing wheel spin is the name of the game, then we should all be riding 4-strokes.
But that isn't going to happen any time soon.


Having said all that, if someone fills the case, then naturally it will improve low end torque, because the air charge will have more velocity.
But is the gain worth the expense? The answer to that is subjective. Everyone has their own finances/pocketbook to work with.
Personally, as I ride for leisure, I don't think the expense is worth the gain.
If someone else wanted to pay for the work for me, then sure, I'll take the gain on your dime!
But please don't overfill my case, because then you will reduce my top end potential doing that.

Edited by 2strokes4me, 28 May 2012 - 03:26 PM.