CR 250 Port Work?

RMRider1
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Edited Date/Time 11/10/2014 8:48pm
Planning to send my '06 CR 250 cylinder and head to Eric Gorr for the port/mill/head work combo. Anyone have any input on this? I think it's called the Mo Better port package. Also not sure if it's worth it to do the pump gas head work or race gas, do I gain that much more power from race gas? My stock setup seems to run fine on 92 non ethanol...Any experience or input appreciated!
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rmartin517
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11/5/2014 5:25pm Edited Date/Time 11/5/2014 5:56pm
May as well go with the race gas mod. Pump gas is getting to the point where race has is needed any way because of detonation. You will gain a much more crisp bike and he can bump the compression up for the race has. Cr 250 needs it as well. If you get your porting and compression correct cr 250 becomes a great bike. To each their own, you will get many diff opinions on this. If you don't mind spending the money on race has you will def benefit from it.
Joko
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Fantasy
11/5/2014 7:18pm
Check out chad watts or PR2 or Varner
- all have lots of experience with that engine
RMRider1
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11/5/2014 7:28pm
rmartin517 wrote:
May as well go with the race gas mod. Pump gas is getting to the point where race has is needed any way because of detonation...
May as well go with the race gas mod. Pump gas is getting to the point where race has is needed any way because of detonation. You will gain a much more crisp bike and he can bump the compression up for the race has. Cr 250 needs it as well. If you get your porting and compression correct cr 250 becomes a great bike. To each their own, you will get many diff opinions on this. If you don't mind spending the money on race has you will def benefit from it.
Thanks, agreed,...
JW381
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11/5/2014 8:27pm
Got my 04 done by him. Was it better? Yes. Was it close to a YZ motor? Not even. Lucky for me, the YZ was way too wild for me, so the more "mellow" CR is a lot more fun. Don't get me wrong, I did notice a solid difference after sending it to Gorr, but it's not magic, so don't expect it. Or, something is wrong with my bike haha.

The Shop

dogger315
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11/6/2014 9:41am
EG did the "mo betta" port and headwork on my CR500. Nice, broad powerband, which is just what I was looking for.
I didn't do the race gas upgrade because I didn't want any more power.

Make sure you realize the mo betta work is not designed for big gains in power, it's more about smoothing out the
power band while adding just a little. If that's what you're looking for, you'll be happy. As for reshaping the head for
race gas, that's a nice mod if you don't mind being tied to the extra cost for fuel. Some states have gas stations that
sell premium ethanol free pump gas and that's what I run in my CR500. Works great and doesn't cost a bunch. My
CR250s have highly modified heads (and port work), done by Tom Morgan, and they get uber expensive VP MRX02.
This gas also works great (unusual smell too), so I work both sides of the race gas debate.

Sounds like with the mild port work you selected, you'd be better off going with ethanol free premium pump gas. If you
want more power, you can always send the head in for reshaping and switch to race gas.

Something to consider.

dogger

RMRider1
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11/6/2014 10:06am
dogger315 wrote:
EG did the "mo betta" port and headwork on my CR500. Nice, broad powerband, which is just what I was looking for. I didn't do the...
EG did the "mo betta" port and headwork on my CR500. Nice, broad powerband, which is just what I was looking for.
I didn't do the race gas upgrade because I didn't want any more power.

Make sure you realize the mo betta work is not designed for big gains in power, it's more about smoothing out the
power band while adding just a little. If that's what you're looking for, you'll be happy. As for reshaping the head for
race gas, that's a nice mod if you don't mind being tied to the extra cost for fuel. Some states have gas stations that
sell premium ethanol free pump gas and that's what I run in my CR500. Works great and doesn't cost a bunch. My
CR250s have highly modified heads (and port work), done by Tom Morgan, and they get uber expensive VP MRX02.
This gas also works great (unusual smell too), so I work both sides of the race gas debate.

Sounds like with the mild port work you selected, you'd be better off going with ethanol free premium pump gas. If you
want more power, you can always send the head in for reshaping and switch to race gas.

Something to consider.

dogger

Very useful info dogger, I do have access to the non ethanol so may go that route. Really just looking to smooth out that abrupt hit in the middle and make it more manageable...thanks!
CamP
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11/6/2014 11:42am Edited Date/Time 11/6/2014 11:49am
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas. If you have access to 100LL avgas, you can save money with it by mixing it 2:1 with a good fuel like C12. The mill job can be performed by any good machinist, including Gorr, for about $50. A rejetted '00-up YZ250 carb is the next best addition.

I have this exact setup on my 07. Matt Bisceglia has done many laps on my bike and he loves how it runs compared to his stock 07 CR250. It has much broader power that fills the vacant low end of the stocker, boosts the mid-range, and no loss of top end over-rev.
RMRider1
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11/6/2014 11:59am
CamP wrote:
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas...
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas. If you have access to 100LL avgas, you can save money with it by mixing it 2:1 with a good fuel like C12. The mill job can be performed by any good machinist, including Gorr, for about $50. A rejetted '00-up YZ250 carb is the next best addition.

I have this exact setup on my 07. Matt Bisceglia has done many laps on my bike and he loves how it runs compared to his stock 07 CR250. It has much broader power that fills the vacant low end of the stocker, boosts the mid-range, and no loss of top end over-rev.
Yeah, I have the PWK off of a 05 RM . CEJ needle, per your recommendation 178 main and 45 slow with TPS plugged in. Just not sure, pump gas non ethanol is so easy to get, I have to travel 30 min for VP, not sure if it is worth it for me.....
RMRider1
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11/6/2014 2:56pm
CamP wrote:
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas...
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas. If you have access to 100LL avgas, you can save money with it by mixing it 2:1 with a good fuel like C12. The mill job can be performed by any good machinist, including Gorr, for about $50. A rejetted '00-up YZ250 carb is the next best addition.

I have this exact setup on my 07. Matt Bisceglia has done many laps on my bike and he loves how it runs compared to his stock 07 CR250. It has much broader power that fills the vacant low end of the stocker, boosts the mid-range, and no loss of top end over-rev.
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient power delivery?...
CamP
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11/6/2014 3:43pm Edited Date/Time 11/6/2014 4:03pm
RMRider1 wrote:
Yeah, I have the PWK off of a 05 RM . CEJ needle, per your recommendation 178 main and 45 slow with TPS plugged in. Just...
Yeah, I have the PWK off of a 05 RM . CEJ needle, per your recommendation 178 main and 45 slow with TPS plugged in. Just not sure, pump gas non ethanol is so easy to get, I have to travel 30 min for VP, not sure if it is worth it for me.....
I also have a 30 minute drive to get Avgas and C12 so I buy 15 gallons of fuel at a time. I burn about 3 gallons a week so that lasts me about 5 weeks of riding.

If you are determined to use pump gas after milling the cylinder base, you can add 2.5cc to the head's dome volume. You won't get as much snap off the bottom, but it will still be a big improvement. Gorr is well versed in the base and head work, and it's $100 to do both. The actual cylinder porting is excellent from the factory and you won't get much gain from additional porting.
CamP
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11/6/2014 3:46pm
RMRider1 wrote:
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient...
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient power delivery?...
I've come to the conclusion that Honda's final port timing spec's were done on the dyno. These bikes are dyno queens, but that doesn't translate on the track. Retarding the port timing does good things on the track.
RMRider1
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11/6/2014 4:16pm
RMRider1 wrote:
Yeah, I have the PWK off of a 05 RM . CEJ needle, per your recommendation 178 main and 45 slow with TPS plugged in. Just...
Yeah, I have the PWK off of a 05 RM . CEJ needle, per your recommendation 178 main and 45 slow with TPS plugged in. Just not sure, pump gas non ethanol is so easy to get, I have to travel 30 min for VP, not sure if it is worth it for me.....
CamP wrote:
I also have a 30 minute drive to get Avgas and C12 so I buy 15 gallons of fuel at a time. I burn about 3...
I also have a 30 minute drive to get Avgas and C12 so I buy 15 gallons of fuel at a time. I burn about 3 gallons a week so that lasts me about 5 weeks of riding.

If you are determined to use pump gas after milling the cylinder base, you can add 2.5cc to the head's dome volume. You won't get as much snap off the bottom, but it will still be a big improvement. Gorr is well versed in the base and head work, and it's $100 to do both. The actual cylinder porting is excellent from the factory and you won't get much gain from additional porting.
CamP, if I will see a noticeable gain from using race gas, you have me sold? I'm all in if it will help this bear off the bottom end. This thing stock is almost like 2000 rom to 7,000 rpm in a millisecond! Such a dog on the track stock in tight corners unless you are clutching the daylights out of it out of a corner!
CamP
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11/6/2014 4:27pm
RMRider1 wrote:
CamP, if I will see a noticeable gain from using race gas, you have me sold? I'm all in if it will help this bear off...
CamP, if I will see a noticeable gain from using race gas, you have me sold? I'm all in if it will help this bear off the bottom end. This thing stock is almost like 2000 rom to 7,000 rpm in a millisecond! Such a dog on the track stock in tight corners unless you are clutching the daylights out of it out of a corner!
You'll love the race gas version then. If you can't get a good deal on VP, then Sunoco Standard and Supreme will also do a good job. It seems like Sunoco is prevalent and pretty cheap on the East coast.
11/6/2014 5:28pm
Had Eric do the mo/betta on my 05 kx, 250 and all i can say is wow. I went all the way amdhad the head cut for race gas amd had finishline racing polish the gears and shifting components in the bottom end..
My bike had more lowend, but it was the midrange and topend that really ripped. Maybe he accidentaly ported for topend, but all i can say is there wasnt a 450 on the track that out accelerated it. It was super quick and very, very potent.
I loved it.. .absolutely loved it.
11/6/2014 8:50pm Edited Date/Time 11/6/2014 9:09pm
I think a really hot setup for your bike would be an Eric Goore mid-top port job, cut for race gas and 2 teeth lower gearing out back..
Your never gona get the lowend power you want out of that engine, but you certainly can make it one of the fastest bikes around with a good mid-top port job. Then the 2 teeth lower gearing will bring all that power down a bit, so you'll loose 5-7 mph on top speed. so what, I don't see anybody racing at 70 mph around the track. .
I say go for the biggest gains you can get, then if it's too gnarly, do like I had to do AMD put an 11oz fww on it..
RMRider1
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11/7/2014 4:37am Edited Date/Time 11/7/2014 4:39am
I think a really hot setup for your bike would be an Eric Goore mid-top port job, cut for race gas and 2 teeth lower gearing...
I think a really hot setup for your bike would be an Eric Goore mid-top port job, cut for race gas and 2 teeth lower gearing out back..
Your never gona get the lowend power you want out of that engine, but you certainly can make it one of the fastest bikes around with a good mid-top port job. Then the 2 teeth lower gearing will bring all that power down a bit, so you'll loose 5-7 mph on top speed. so what, I don't see anybody racing at 70 mph around the track. .
I say go for the biggest gains you can get, then if it's too gnarly, do like I had to do AMD put an 11oz fww on it..
Certainly food for thought...however, I can't break the habit of riding this thing like my RMZ 450! I watch my gopro footage and I'm thinking "Wring that thing out you idiot" it's just how I ride. Not saying I can't change that style to more suit the mid to top end beast these things have the potential to be, we'll see, appreciate all comments though, this all helps!
O___o
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11/7/2014 5:15am
the solution to everything is to mill .030 off the base and put a PWK on it LMFAO


CamP
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11/7/2014 7:50am
O___o wrote:
the solution to everything is to mill .030 off the base and put a PWK on it LMFAO


It is for the 05-07 CR250. If you actually owned one, you might know that.
11/7/2014 4:46pm
I think a really hot setup for your bike would be an Eric Goore mid-top port job, cut for race gas and 2 teeth lower gearing...
I think a really hot setup for your bike would be an Eric Goore mid-top port job, cut for race gas and 2 teeth lower gearing out back..
Your never gona get the lowend power you want out of that engine, but you certainly can make it one of the fastest bikes around with a good mid-top port job. Then the 2 teeth lower gearing will bring all that power down a bit, so you'll loose 5-7 mph on top speed. so what, I don't see anybody racing at 70 mph around the track. .
I say go for the biggest gains you can get, then if it's too gnarly, do like I had to do AMD put an 11oz fww on it..
RMRider1 wrote:
Certainly food for thought...however, I can't break the habit of riding this thing like my RMZ 450! I watch my gopro footage and I'm thinking "Wring...
Certainly food for thought...however, I can't break the habit of riding this thing like my RMZ 450! I watch my gopro footage and I'm thinking "Wring that thing out you idiot" it's just how I ride. Not saying I can't change that style to more suit the mid to top end beast these things have the potential to be, we'll see, appreciate all comments though, this all helps!
They have the potential to be more than just mid, -top end beasts. They have the potential to win races against any bike on the track..
But your rite, its a 2 stroke and it's strength's has to be taken advantage of.
And those advantages are light weight, excellent handling, awsome acceleration, and an aggressive overall nature.
I used to never let off the gas in corners on my kx, I just used the clutch to meter the power out untill Icould let it all the way out without fflipping.
Riding a 2 stroke like a 4 stroke will never work, get comfy riding wide open and using the clutch to meter the power and realize the true potential of that awsome CR 250.
CamP
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11/7/2014 6:08pm Edited Date/Time 11/7/2014 6:18pm
Just shave the base. You will love it. Porting a 05-07 CR250 for mid/top would be a huge mistake for the OP and 99% of the riding public.
RMRider1
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11/8/2014 11:12am
CamP wrote:
Just shave the base. You will love it. Porting a 05-07 CR250 for mid/top would be a huge mistake for the OP and 99% of the...
Just shave the base. You will love it. Porting a 05-07 CR250 for mid/top would be a huge mistake for the OP and 99% of the riding public.
Cutting the base as well as the head work for race gas is your recommendation CamP, correct?
11/8/2014 11:47am
CamP wrote:
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas...
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas. If you have access to 100LL avgas, you can save money with it by mixing it 2:1 with a good fuel like C12. The mill job can be performed by any good machinist, including Gorr, for about $50. A rejetted '00-up YZ250 carb is the next best addition.

I have this exact setup on my 07. Matt Bisceglia has done many laps on my bike and he loves how it runs compared to his stock 07 CR250. It has much broader power that fills the vacant low end of the stocker, boosts the mid-range, and no loss of top end over-rev.
RMRider1 wrote:
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient...
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient power delivery?...
I did the mods Cam P is talking about to my 2006 CR250R and it made a huge difference. The bottom end power increase was the most noticeable for me. Eric Gorr did the cylinder milling (for $75) and I got the YZ carb ( $100 ish) and I run VP 110.

1
RMRider1
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11/8/2014 1:01pm
CamP wrote:
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas...
If you want the best bang for your buck for the 05-07 CR250, simply mill .030" off the base of the cylinder and run race gas. If you have access to 100LL avgas, you can save money with it by mixing it 2:1 with a good fuel like C12. The mill job can be performed by any good machinist, including Gorr, for about $50. A rejetted '00-up YZ250 carb is the next best addition.

I have this exact setup on my 07. Matt Bisceglia has done many laps on my bike and he loves how it runs compared to his stock 07 CR250. It has much broader power that fills the vacant low end of the stocker, boosts the mid-range, and no loss of top end over-rev.
RMRider1 wrote:
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient...
Funny, so simple ...sound too easy and too good to be true...Did Honda just produce these engines (05-07) without any thought about correct squish or efficient power delivery?...
I did the mods Cam P is talking about to my 2006 CR250R and it made a huge difference. The bottom end power increase was the...
I did the mods Cam P is talking about to my 2006 CR250R and it made a huge difference. The bottom end power increase was the most noticeable for me. Eric Gorr did the cylinder milling (for $75) and I got the YZ carb ( $100 ish) and I run VP 110.

Nice looking scooter! Yea, that's what I would run or maybe C12...
CamP
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11/9/2014 3:24pm Edited Date/Time 11/9/2014 3:28pm
RMRider1 wrote:
Cutting the base as well as the head work for race gas is your recommendation CamP, correct?
No, if you run a leaded high octane race gas like VP 110/C12 or Sunoco standard/supreme, you don't need to touch the head.
JW381
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11/10/2014 3:45pm
I need to ride someone else's gen3 CR250 to compare to mine. It's definitely quick and improved after sending it to Gorr, but I always wonder how it compares to others. Hard to know if my bike is working properly without a similar example to compare it to.
11/10/2014 8:48pm Edited Date/Time 11/10/2014 8:49pm
If you got the mid-top port job, cut for race gas, you woudn't be wandering, you'd know..
You wouldn't be saying its quicker and improved, you'd be saying, this is the quickest bike I've ever ridden. Then you wouldn't be looking for other cr 250's to mess with, you'd be looking or 450's to smoke.. Not trying to be a smartass, just saying. I've been down that road, and my kx 250 ate 450's for lunch, as far as outrite acceleration goes..

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