Pro-Circuit Head and Cylinder Modifications Service '07 CR250

[frdbtr]

X3 

 

Wanna do this to my '03.. wonder how the results would differ with the older style case reed engine.. hmm...?

 

Oh, I think you wouldn't see much difference (as far as power everywhere).  I'm sure it would put a big smile on your face.  PC knows what they are doing. 

[MotoGuido]

Oh, I think you wouldn't see much difference (as far as power everywhere). I'm sure it would put a big smile on your face. PC knows what they are doing.

Too late sent it to Tom Morgan Racing. It's stupid fast now.

[frdbtr]

Too late sent it to Tom Morgan Racing. It's stupid fast now.

 

Oh Jeez, I didn't realize that your post was a year old.  I just saw 13th of june ?.  Now I remember talking to you about your bike after you had the work done LOL!  That is what I get for not paying close enough attention to post dates.

[jmc02]

Ohh wow guys I completely forgot about this thread. I'm taking the bike out this weekend a bunch to blow the cobwebs off of it. I crossed over into the dark side and bought a new 450 and have been riding that a bunch. Ill get the 250 out and post a youtube video of my helmet cam riding the 250. Again sorry guys, been really busy with college and work. Haven't had time to ride at all. Last time I rode was last July 2014 haha. Been a while!

What? You had mods done done from PC that most of us would love to have done and then went out and bought a 450f? Just kidding. A ride video would be awesome and thanks for a good write up. I must of missed this thread first time around.

[Speeddemon73]

What? You had mods done done from PC that most of us would love to have done and then went out and bought a 450f? Just kidding. A ride video would be awesome and thanks for a good write up. I must of missed this thread first time around.

aHHH! Stop it with the guilt trip hahaha. I'll have a video up Friday night or Saturday after practice on Friday. 

[New to 4S-Joe]

Chad Watts like the stock Mikuni too! He says the general public is under the misconception that the PWK is better. He says him and RC tested the PWK and his modded Mikuni is better. I'm sure with RC racing against the thumpers his CR 250 had to be a beast to compete. I had him do my carb, but I haven't got to test it I'm waiting on funds to get the whole motor done! I can say this Chads work is second to none that I've experienced.

[H4L]

Chad Watts like the stock Mikuni too! He says the general public is under the misconception that the PWK is better. He says him and RC tested the PWK and his modded Mikuni is better. I'm sure with RC racing against the thumpers his CR 250 had to be a beast to compete. I had him do my carb, but I haven't got to test it I'm waiting on funds to get the whole motor done! I can say this Chads work is second to none that I've experienced.

Joe - Stock vs. stock on the carbs the Keihin is a better option as it will have better off idle roll on power when jetted optimum.   I did my own testing & was never able to get the mikuni to duplicate that & had a slight hesitation off idle that couldn't be corrected with jetting.   That being said I could feel modest gains from mid to top with the mikuni on the 03 with PC motor mods.  

 

I'd be interested in hearing a ride report when your able to post as I'd be willing to send Chad my mikuni to experiment as well.   Are the carb mods geared to improving off idle lowend response ?       

Edited July 2, 2015 by H4L

[MotoGuido]

What? You had mods done done from PC that most of us would love to have done and then went out and bought a 450f? .

Yeah that's whack!!

[Speeddemon73]

Here you go guys. Last practice of the day, super tired, and rough sand track. 

 

https://www.youtube.com/watch?v=bFLWWcKHb_4&feature=youtu.be

[cmjb]

Sounds good. Out of curiosity what gearing are you running?

[wsc96]

Track looks like fun!

[Speeddemon73]

Sounds good. Out of curiosity what gearing are you running?

13-50, has a good pull off the bottom and still has plenty of top end pull to carry gears longer.

[Speeddemon73]

Track looks like fun!

 

It's my favorite track in Michigan by far. The people running the facility are the nicest people you will ever meet and the track is always groomed and prepped on practice days like it was a big race weekend. 

[jmc02]

Looking good, bike sounds good too! Thanks for the video!

[H4L]

Nice...   Thanks for posting the vid.

With the PC mods you can hear the motor has good snap & revs fast into a monstrous topend overev.   Also running a 13/50 gear combo that has no problem pulling up top & have never run out of motor before I go into the next corner.    

[Speeddemon73]

Thanks guys for all the kind words!

[Speeddemon73]

So hey guys, I am thinking of experimenting with my bike a little bit. I never ran the bike with the stock Mikuni TMX after the engine mods. I have been back reading some threads and looks like some users had their squish fixed via RB Mods and after that the stock Mikuni seemed to work great. I think I might give it a test tonight and see how she runs compared to the Keihin PWK that is on it now. The Mikuni probably fits way better. The Keihin is a little difficult to get to fit to be honest. Might have to try and sell mine and opt for the short body PWK. I think the long body might be creating an air leak to be honest. Who knows? I will report back with my findings ?

[MXandSXracer21]

So hey guys, I am thinking of experimenting with my bike a little bit. I never ran the bike with the stock Mikuni TMX after the engine mods. I have been back reading some threads and looks like some users had their squish fixed via RB Mods and after that the stock Mikuni seemed to work great. I think I might give it a test tonight and see how she runs compared to the Keihin PWK that is on it now. The Mikuni probably fits way better. The Keihin is a little difficult to get to fit to be honest. Might have to try and sell mine and opt for the short body PWK. I think the long body might be creating an air leak to be honest. Who knows? I will report back with my findings ?

How'd testing go?

[Speeddemon73]

Well I went to Wednesday night practice with my friends at one of the "local" tracks after work. I say local because its about 45min away. Track was pretty mushy, not muddy, more like race day morning. Deep sand/clay/loam. Fired the bike up with the Mikuni using Pro-Circuit's recommended jetting. Warmed the bike up and went out for a lap before getting flagged back in as the minis were going out. My overall thought was that the bike just didn't seem to have the overall crispness like it did with the Keihin. The Mikuni has a little better pull, but no snap on bottom. The ruts from practice were about footpeg high every corner so bottom to mid pull was of the essence. Put the Keihin back on with the setting that I wanted to try on the track and man does it run amazing now. I mean it ran great before, but woah buddy!. Mid to top you better hold your undies. She likes to eat now, went out for a quick 10min moto and the bike ate about 1/3-1/2 of a tank worth of fuel. Runs like my 125 did in its prime. Took the plug out this evening to see how my jetting was and well, you guys have a look. I think its pretty well spot on. Not too lean, but not to rich either. Nice and cinnamon-chocolate brown. MMMMMMMM! I think I am going to keep the Keihin with it running so good.

 

Edited July 10, 2015 by Speeddemon73

[frdbtr]

Well I went to Wednesday night practice with my friends at one of the "local" tracks after work. I say local because its about 45min away. Track was pretty mushy, not muddy, more like race day morning. Deep sand/clay/loam. Fired the bike up with the Mikuni using Pro-Circuit's recommended jetting. Warmed the bike up and went out for a lap before getting flagged back in as the minis were going out. My overall thought was that the bike just didn't seem to have the overall crispness like it did with the Keihin. The Mikuni has a little better pull, but no snap on bottom. The ruts from practice were about footpeg high every corner so bottom to mid pull was of the essence. Put the Keihin back on with the setting that I wanted to try on the track and man does it run amazing now. I mean it ran great before, but woah buddy!. Mid to top you better hold your undies. She likes to eat now, went out for a quick 10min moto and the bike ate about 1/3-1/2 of a tank worth of fuel. Runs like my 125 did in its prime. Took the plug out this evening to see how my jetting was and well, you guys have a look. I think its pretty well spot on. Not too lean, but not to rich either. Nice and cinnamon-chocolate brown. MMMMMMMM! I think I am going to keep the Keihin with it running so good.

 

 

What settings were you running with the PWK?