Full Tilt CR250 Build - MXA Two Stroke Hall of Fame

blackdiamond
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Grapevine, TX, USA
1/12/2016 1:47am
I responded previously, in that message I had indicated that the simple carbon fiber plate that I had sourced for small brackets and the like were easily found on eBay.
blackdiamond
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Grapevine, TX, USA
1/12/2016 10:17am
I am not sure if any of you have tried these SKS low friction wheel bearing seal sets so I wanted to share this.

I typically use all OEM bearings and seals and I have to admit I was skeptical and wasn't convinced they would really do much. I was dead wrong, these seals work killer and just spinning the hub with your hand while mounted on the bike you can feel a huge difference in drag. Free HP Smile

$27 on eBay and that includes the spacers too.








ratonmacias
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1203
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4/1/2008
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Guadalajara, MX
1/12/2016 10:24am Edited Date/Time 1/12/2016 10:25am
those seals and spacers look so trick. hey whenever you have more info on the 2004 cr 250 black box let me know. specially if it fills the dip when the pv opens.
Bultaco
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1745
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1/20/2014
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Planet, VT, USA
1/12/2016 10:28am
Thanks for this thread about a dirt bike. It is a welcome relief to the fight club drama going on elsewhere in the moto world.

Everything on your project looks perfect. Can't wait to hear it run and see it roost.

The Shop

blackdiamond
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Grapevine, TX, USA
1/12/2016 10:42am
those seals and spacers look so trick. hey whenever you have more info on the 2004 cr 250 black box let me know. specially if it...
those seals and spacers look so trick. hey whenever you have more info on the 2004 cr 250 black box let me know. specially if it fills the dip when the pv opens.
I am actually doing some programming tonight on the ignition.
blackdiamond
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Grapevine, TX, USA
1/12/2016 10:56am




blackdiamond
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1363
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Grapevine, TX, USA
1/12/2016 11:04am
I had the outlet tubes and the corners welded on the OEM radiators. I also revised the coolant hose routing to resemble the newer Hondas, RM250 and the YZ250. This eliminates one return hose, a few clamps, a crossover vent tube and a plastic fitting. Less weight and less to go wrong. I will try to get some pics of the top radiator tanks showing the mods soon.



Reefer Sutherland
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Bluefield, VA, USA
1/12/2016 11:08am
Do us a solid, and look at the serial number printed on the SKF bearing. Post it.
blackdiamond
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Grapevine, TX, USA
1/12/2016 11:09am


blackdiamond
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Grapevine, TX, USA
1/12/2016 11:16am
Do us a solid, and look at the serial number printed on the SKF bearing. Post it.
The bearings are OEM, I just used the seals and spacers.
blackdiamond
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Grapevine, TX, USA
1/12/2016 12:16pm
Before and after pics of the ignition cover.

The cover had some oxidation on it that needed to be cleaned up so I sanded it down and also removed the "made in Japan" lettering at the same time. I finished it by bead blasting it and ended up with a cool satin finish. I'm not a big fan of overly polished dirt bikes. I want it to look like a dirt scooter not a Harley at a SEMA show.







Underground
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4205
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Location
AQ
1/12/2016 12:32pm
Do us a solid, and look at the serial number printed on the SKF bearing. Post it.
The bearings are OEM, I just used the seals and spacers.
Out of the packet genuine? $$$ compared to any Jap made bearings from an aftermarket bearing supplier and of the same quality. Did you look into ceramics?
1/12/2016 12:38pm
Is the water pump and primary cover in that photo anodized? Looks awesome
blackdiamond
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Grapevine, TX, USA
1/12/2016 12:44pm
Yes
jeffro503
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St Helens, OR, USA
1/12/2016 12:45pm
BD......did you end up getting a different designed rear sprocket than the one you have in this pic here? I think you discussed possibly doing so earlier in the thread. Seems quite a few guys came to the conclusion that this design is flawed and may cause an issue. The one you have l;ooks to be supported a little more than the other sprockets I saw that failed , but why take a chance?

AHRMA361
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Location
NE, OH, USA
1/12/2016 12:52pm
jeffro503 wrote:
BD......did you end up getting a different designed rear sprocket than the one you have in this pic here? I think you discussed possibly doing so...
BD......did you end up getting a different designed rear sprocket than the one you have in this pic here? I think you discussed possibly doing so earlier in the thread. Seems quite a few guys came to the conclusion that this design is flawed and may cause an issue. The one you have l;ooks to be supported a little more than the other sprockets I saw that failed , but why take a chance?

That's a Talon sprocket. I have used them over the years...450 & 250F's and 250 2T's. Never had an issue.

I suspect failures are more maintenance, bolt loosening issues rather than the design. Just MHO.
philG
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GB
1/12/2016 12:56pm
Ceramic bearings are awesome, we ran some on the SM bike , with low friction seals and coated spacers , and spent a lot of time on sorting out the front brake alignment and pad fitment, along with caliper seals , to the point where it would spin like a bicycle wheel.. like you say , free horsepower.

Cheap alternative is use stock seals and remove the spring,bearings are sealed anyway. Makes a difference.

blackdiamond
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Grapevine, TX, USA
1/12/2016 1:03pm
Out of the packet genuine? $$$ compared to any Jap made bearings from an aftermarket bearing supplier and of the same quality. Did you look into...
Out of the packet genuine? $$$ compared to any Jap made bearings from an aftermarket bearing supplier and of the same quality. Did you look into ceramics?
I did but I didn't think it would be worth the extra cost. The weight savings is minimal but on the flip side of that I hear they reduce drag in a big way. If moto had higher speeds like GP bikes I think it would be a must have. You never know, I might still try it if I could find a quality manufacturer that was reasonably priced.
blackdiamond
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Grapevine, TX, USA
1/12/2016 1:12pm Edited Date/Time 1/12/2016 1:14pm
jeffro503 wrote:
BD......did you end up getting a different designed rear sprocket than the one you have in this pic here? I think you discussed possibly doing so...
BD......did you end up getting a different designed rear sprocket than the one you have in this pic here? I think you discussed possibly doing so earlier in the thread. Seems quite a few guys came to the conclusion that this design is flawed and may cause an issue. The one you have l;ooks to be supported a little more than the other sprockets I saw that failed , but why take a chance?

It works OK for this guy so I thought it was worth the risk Smile

All kidding aside, I have used these sprockets for years and I honestly think they are the best sprocket available. They are must more wear resistant than Renthal sprockets IMO and a bit lighter as well.



blackdiamond
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Grapevine, TX, USA
1/12/2016 2:38pm
philG wrote:
Ceramic bearings are awesome, we ran some on the SM bike , with low friction seals and coated spacers , and spent a lot of time...
Ceramic bearings are awesome, we ran some on the SM bike , with low friction seals and coated spacers , and spent a lot of time on sorting out the front brake alignment and pad fitment, along with caliper seals , to the point where it would spin like a bicycle wheel.. like you say , free horsepower.

Cheap alternative is use stock seals and remove the spring,bearings are sealed anyway. Makes a difference.

I have seen videos of track bikes where they do back to back tests with the front wheel lifted off the ground and the ceramics spin about 5 times longer with the same effort.
blackdiamond
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Grapevine, TX, USA
1/12/2016 10:21pm
I finally finished the footpegs tonight. These are the older version of the Lightspeed titanium Honda pegs with the post mount spring. They do not make them in this version anymore, but after endless searching I finally found a set on eBay for $75. The reason I like to use the old version is you can machine the spring post off the bottom and weld a new one on the top. This effectively lowers the pegs about 7mm and moves them back about 5mm without changing the brackets. That is sort of a big deal when you are 6'2"

After that it takes a bit of minor machine work to insure they clear the heads of the fasteners after being lowered and they are good to go.







philG
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GB
1/13/2016 1:46am
philG wrote:
Ceramic bearings are awesome, we ran some on the SM bike , with low friction seals and coated spacers , and spent a lot of time...
Ceramic bearings are awesome, we ran some on the SM bike , with low friction seals and coated spacers , and spent a lot of time on sorting out the front brake alignment and pad fitment, along with caliper seals , to the point where it would spin like a bicycle wheel.. like you say , free horsepower.

Cheap alternative is use stock seals and remove the spring,bearings are sealed anyway. Makes a difference.

I have seen videos of track bikes where they do back to back tests with the front wheel lifted off the ground and the ceramics spin...
I have seen videos of track bikes where they do back to back tests with the front wheel lifted off the ground and the ceramics spin about 5 times longer with the same effort.
For the WRC cars I worked on Cerrobear was our supplier of choice , they did a lovely wheel bearing that was around 150mm OD/ 135mm ID , and around 12mm deep, we ran 2 per hub with 70mm spacing and never had a failure.


One of the tracks we have had Tech at the bottom of a slope, and our 450 had pretty much as much as you could do done with bearings /brakes etc for rolling resistance, we ran super expensive chains that we got from a Moto2 team that had done 1 race weekend . They were loose as a goose , the thing rolled like you wouldn't believe, where as the next best bike, barely made it down the slope.

We always did a coastdown test at the end of the day with the WRC car to check that nothing was dragging , run the car up to 100kph and then put your foot on the clutch , see how long she rolls for.. new caliper seals once gave us an improvement from 200m to nearly 800m.. little things all add up.


I agree with you for MX though , its difficult to justify the expense when you cant feel the difference, but when you rolled the bike out the back of the van , you could feel it.

bonseff
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Frisco, TX, USA
1/13/2016 7:17am
I recently finished a frame-up rebuild on my 03 and thought I did a decent job.
Then I see this thread and it makes me think not so much!

So much trickness to this build, its awesome.
dl117
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1547
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2/8/2007
Location
Cambridge, MN, USA
1/13/2016 7:56am
ceramic bearings are nice, my kid has them in his BMX bike, in his hubs and bottom bracket.....spin like a dream.

Oh and this build makes the swimsuit area feel a little puffy...lol
Prototype
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1
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1/13/2016
Location
San Jose, CA, USA
1/13/2016 7:12pm
Thank you for taking the time to document and present your build! The attention to detail is second to none! And you've got me drooling because I own a 2002 CR250 and wish I had the resources and knowledge to do a fraction of the things you've put into this build.

I know you provided some detail on the relocation of your ignition box (first page) but while I have a rough idea of where it's new location is on you build, I'm having a hard time envisioning it. May I request some pictures of it's new location as the bike comes together? I'm beginning to document what upgrades I'd like to do on my own, and the HPSD is on the list but didn't like where some have relocated their ignition boxes.

Keep up the amazing work!
blackdiamond
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1363
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Location
Grapevine, TX, USA
1/13/2016 10:08pm
Prototype wrote:
Thank you for taking the time to document and present your build! The attention to detail is second to none! And you've got me drooling because...
Thank you for taking the time to document and present your build! The attention to detail is second to none! And you've got me drooling because I own a 2002 CR250 and wish I had the resources and knowledge to do a fraction of the things you've put into this build.

I know you provided some detail on the relocation of your ignition box (first page) but while I have a rough idea of where it's new location is on you build, I'm having a hard time envisioning it. May I request some pictures of it's new location as the bike comes together? I'm beginning to document what upgrades I'd like to do on my own, and the HPSD is on the list but didn't like where some have relocated their ignition boxes.

Keep up the amazing work!
I am making some changes to the bracket and will post more when I get it finished but this will give you a general idea of what I have in mind.



1/14/2016 12:11pm
I responded previously, in that message I had indicated that the simple carbon fiber plate that I had sourced for small brackets and the like were...
I responded previously, in that message I had indicated that the simple carbon fiber plate that I had sourced for small brackets and the like were easily found on eBay.
Ah thanks. I just realized that my email address linked to my profile is old and no longer valid.

THanks for the headsup on where to find the materials. I appreciate it.

Righteous build you have going on!
colintrax
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4695
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8/25/2015
Location
Taylorsville, GA, USA
1/14/2016 6:20pm
Prototype wrote:
Thank you for taking the time to document and present your build! The attention to detail is second to none! And you've got me drooling because...
Thank you for taking the time to document and present your build! The attention to detail is second to none! And you've got me drooling because I own a 2002 CR250 and wish I had the resources and knowledge to do a fraction of the things you've put into this build.

I know you provided some detail on the relocation of your ignition box (first page) but while I have a rough idea of where it's new location is on you build, I'm having a hard time envisioning it. May I request some pictures of it's new location as the bike comes together? I'm beginning to document what upgrades I'd like to do on my own, and the HPSD is on the list but didn't like where some have relocated their ignition boxes.

Keep up the amazing work!
I am making some changes to the bracket and will post more when I get it finished but this will give you a general idea of...
I am making some changes to the bracket and will post more when I get it finished but this will give you a general idea of what I have in mind.



Are you concerned about the close proximity to the exhaust? 2 stroke pipes don't get as hot as the thumper pipes.... but they certainly get hot enough to melt solder. Maybe some heat tape to protect it?
Zesiger 112
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Galveston, TX, USA
1/14/2016 6:36pm
[img]https://p.vitalmx.com/photos/forums/2016/01/12/119543/s1200_CAM00063.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/01/12/119544/s1200_20151218_221529.jpg[/img]




Where are you getting those drilled bolts from?
1/14/2016 6:36pm
Your build is pretty amazing, which I'm sure you already know by the amount of attention this thread has received.

Thanks for sharing it with us all.

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