Full Tilt CR250 Build - MXA Two Stroke Hall of Fame

Michael Scott 2/27/2016 3:25pm
2/27/2016 3:25pm
Maybe some of you have done this, but I just dropped a torque wing in my 02 and the bottom end came to life. I wasn't sure what to expect but I've been very satisfied.
blackdiamond
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blackdiamond 2/27/2016 6:38pm
2/27/2016 6:38pm
Michael Scott wrote:
Maybe some of you have done this, but I just dropped a torque wing in my 02 and the bottom end came to life. I wasn't...
Maybe some of you have done this, but I just dropped a torque wing in my 02 and the bottom end came to life. I wasn't sure what to expect but I've been very satisfied.
What do you mean by a torque wing?
Michael Scott 2/27/2016 7:53pm
2/27/2016 7:53pm



It's made by Thunder Products, installed on the engine side of the carb. It helps air flow into the reeds
blackdiamond
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blackdiamond 2/27/2016 10:39pm
2/27/2016 10:39pm
Ok, now I know what you mean. I think Dick's Racing offers them as well?

The Shop

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Michael Scott 2/28/2016 7:29am
2/28/2016 7:29am
Yup, pretty much the same thing!
blackdiamond
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blackdiamond 2/28/2016 9:35pm
2/28/2016 9:35pm
RMRider1 wrote:
I cannot speak to how a long body compares but I will tell you my CR sounds like yours on the stand and the response does...
I cannot speak to how a long body compares but I will tell you my CR sounds like yours on the stand and the response does translate directly to the track! Huge difference from the stock Mikuni that comes stock on the late model CR's....I would recommend this carb for sure on your bike. Interested to see input on how the mapping translates to the track as well! BTW.. My jetting ended up being 175 mj, 42 pilot.. As mentioned power jet plugged though and TPS connected...Amsoil Interceptor 32:1... FYI...
I rode the bike for the first time on a short 15 minute shakedown session today. WOW, that carb feels awesome!

With that said, we have so many changes and mods on this engine when you include the transmission changes, carb and ignition. I am not sure if the carb is solely responsible for what I was feeling but the throttle response is unbelievable. I am sure some of this is because of the ignition as well but I can't confirm that without testing back to back.
CLT809
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CLT809 2/29/2016 10:13am
2/29/2016 10:13am
Amazing build, very impressed. I do have a couple of questions regarding the newer generation crf forks.
1) Did you measure the fork length of the original and the crf forks? I seem to remember the older twin chamber forks I had sitting around being a good bit longer than the forks that came on my 2010 450, but I've slept since then.
2) It appears you mounted the 450 triple clamps as well, do those bolt right up, or did you need to swap steering stems?
Thanks for sharing the awesome details involved in the build!
Reefer Sutherland 2/29/2016 10:15am
2/29/2016 10:15am
Dick's got all his stuff from Thunder, installed it, and charged double what Thunder did. I have that torque wing as well.
blackdiamond
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blackdiamond 2/29/2016 12:18pm
2/29/2016 12:18pm
CLT809 wrote:
Amazing build, very impressed. I do have a couple of questions regarding the newer generation crf forks. 1) Did you measure the fork length of the...
Amazing build, very impressed. I do have a couple of questions regarding the newer generation crf forks.
1) Did you measure the fork length of the original and the crf forks? I seem to remember the older twin chamber forks I had sitting around being a good bit longer than the forks that came on my 2010 450, but I've slept since then.
2) It appears you mounted the 450 triple clamps as well, do those bolt right up, or did you need to swap steering stems?
Thanks for sharing the awesome details involved in the build!
If I remember correctly the forks are approximately 1/4" shorter but I can't say for sure. I will say the bike sits completely level with the stock linkage and the forks adjusted as pictured.



blackdiamond
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blackdiamond 2/29/2016 12:53pm
2/29/2016 12:53pm
I decided on a custom lightweight seat foam and gripper cover from Guts Racing. The combo saves approximately 1 pound of weight, most importantly at one of the highest points on the motorcycle. The new no-slip version is designed to increase grip by using channels cut in the foam (also saving weight) instead of using the typical pleats and humps which add weight. The cover fits so well it looks like its already installed in the photo but that's not the case. It's not stapled in the photo.





Tbteam
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Tbteam 2/29/2016 12:59pm
2/29/2016 12:59pm
Sorry if I missed it, but have you posted the post transformation weight of this magnificent bike? Can't wait to find out the weight savings!
blackdiamond
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blackdiamond 2/29/2016 1:08pm
2/29/2016 1:08pm
I haven't weighed it yet.
Underground 2/29/2016 2:00pm
2/29/2016 2:00pm
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right amount so it's not like an enduro bike to rev out. I reckon you may need just a bit with all the mods once you start riding it in Carlsbad summer
blackdiamond
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blackdiamond 3/1/2016 12:31am
3/1/2016 12:31am
Underground wrote:
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right...
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right amount so it's not like an enduro bike to rev out. I reckon you may need just a bit with all the mods once you start riding it in Carlsbad summer
I was definitely considering it, I think there will be an increased need to possibly control wheel-spin considering the rotating weight in the trans has been reduced by over 2 pounds. I have only ridden it up and down the driveway a few times and I can honestly say it feels extremely responsive and lively and that may or may not be a factor? If I was in Vegas I would bet that it would.
Underground 3/1/2016 4:09am
3/1/2016 4:09am
Everyone bets in Vegas
Reefer Sutherland 3/1/2016 4:22am
3/1/2016 4:22am
Underground wrote:
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right...
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right amount so it's not like an enduro bike to rev out. I reckon you may need just a bit with all the mods once you start riding it in Carlsbad summer
blackdiamond wrote:
I was definitely considering it, I think there will be an increased need to possibly control wheel-spin considering the rotating weight in the trans has been...
I was definitely considering it, I think there will be an increased need to possibly control wheel-spin considering the rotating weight in the trans has been reduced by over 2 pounds. I have only ridden it up and down the driveway a few times and I can honestly say it feels extremely responsive and lively and that may or may not be a factor? If I was in Vegas I would bet that it would.
Don't think of the added rotational mass strictly in terms of increased traction. The flywheel weight can and does help carry the power further into the rev range, which, with a 3-speed, you're going to need as many revs as you can get.
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blackdiamond 3/1/2016 9:57am
3/1/2016 9:57am
I am aware of that and I totally agree but I don't think the reduction in transmission weight will have an affect on that?

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Reefer Sutherland 3/1/2016 10:05am
3/1/2016 10:05am
blackdiamond wrote:
I am aware of that and I totally agree but I don't think the reduction in transmission weight will have an affect on that?
Not 100% sure. I would just try it both ways so you have a definitive answer.
Matt Fisher 3/1/2016 10:28am
3/1/2016 10:28am
blackdiamond wrote:
I am aware of that and I totally agree but I don't think the reduction in transmission weight will have an affect on that?
Highly unlikely the rotating mass of a couple of 3" diameter gears will have any kind of significant impact on traction. Your motor mods, suspension and weight reduction will all play much more significant rolls in hooking up.

Likely the removal of the gears will have a bigger impact on how well it shifts, as the output shaft will be able to change it's relative speed easier.

Travis_Hudson 3/1/2016 8:19pm
3/1/2016 8:19pm
Underground wrote:
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right...
Are you going to play with flywheel weights? I've had good experiences with some in terms of improving traction but you need to find the right amount so it's not like an enduro bike to rev out. I reckon you may need just a bit with all the mods once you start riding it in Carlsbad summer
blackdiamond wrote:
I was definitely considering it, I think there will be an increased need to possibly control wheel-spin considering the rotating weight in the trans has been...
I was definitely considering it, I think there will be an increased need to possibly control wheel-spin considering the rotating weight in the trans has been reduced by over 2 pounds. I have only ridden it up and down the driveway a few times and I can honestly say it feels extremely responsive and lively and that may or may not be a factor? If I was in Vegas I would bet that it would.
I put a 8 Oz weight on mine, and it was a huge improvement in getting traction on medium to hard pack track's. I would recommend it. Wink
blackdiamond
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blackdiamond 3/2/2016 1:42am
3/2/2016 1:42am
Travis_Hudson wrote:
I put a 8 Oz weight on mine, and it was a huge improvement in getting traction on medium to hard pack track's. I would recommend...
I put a 8 Oz weight on mine, and it was a huge improvement in getting traction on medium to hard pack track's. I would recommend it. Wink
I haven't used one on the CR in the past but the people I have talked to seem to feel that 8 oz.is the magic number.
1
Underground 3/2/2016 2:26am
3/2/2016 2:26am
This flywheel thing is definitely gaining momentum
RMRider1
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RMRider1 3/2/2016 6:09am
3/2/2016 6:09am
RMRider1 wrote:
I cannot speak to how a long body compares but I will tell you my CR sounds like yours on the stand and the response does...
I cannot speak to how a long body compares but I will tell you my CR sounds like yours on the stand and the response does translate directly to the track! Huge difference from the stock Mikuni that comes stock on the late model CR's....I would recommend this carb for sure on your bike. Interested to see input on how the mapping translates to the track as well! BTW.. My jetting ended up being 175 mj, 42 pilot.. As mentioned power jet plugged though and TPS connected...Amsoil Interceptor 32:1... FYI...
blackdiamond wrote:
I rode the bike for the first time on a short 15 minute shakedown session today. WOW, that carb feels awesome! With that said, we have...
I rode the bike for the first time on a short 15 minute shakedown session today. WOW, that carb feels awesome!

With that said, we have so many changes and mods on this engine when you include the transmission changes, carb and ignition. I am not sure if the carb is solely responsible for what I was feeling but the throttle response is unbelievable. I am sure some of this is because of the ignition as well but I can't confirm that without testing back to back.
Awesome! Glad to hear she rips! Like you said...Probably a little of everything...ie, Varner work, tranny and the carb.. Should be a blast! Please post riding video sometime...
Travis_Hudson 3/3/2016 10:25am
3/3/2016 10:25am
Yeah, a lot of people don't seen to realize the almost all of the factory two stroke from back in the day used some sort of flywheel weight out doors. I was pleasantly surprised when I put mine on.
Mit12
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Mit12 3/3/2016 11:03am
3/3/2016 11:03am
Your bike is a true work of art. You are making a true privateers "works" bike. Great job.
OW38B
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OW38B 3/3/2016 11:13am
3/3/2016 11:13am
Premix4Life wrote:
this thread rules.
I was thinkin' the same thing.

Blackdiamond is doing a fantastic job.........
blackdiamond
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blackdiamond 3/6/2016 5:45pm
3/6/2016 5:45pm
I just need to some track testing and dyno pulls and its ready. And install the graphics of course.



slowgti
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slowgti 3/6/2016 5:47pm
3/6/2016 5:47pm
Yes! More video soon?
blackdiamond
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blackdiamond 3/6/2016 6:01pm
3/6/2016 6:01pm
Shooting for sometime towards the end of the week or next weekend.

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