Full Tilt CR250 Build - MXA Two Stroke Hall of Fame

H4L
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H4L 5/1/2016 8:30am
5/1/2016 8:30am
I noticed you're running a Boyesen Rad Valve. Have you done any dyno testing & compared it to an OEM or Vforce unit ?
I'm still running a VF2 unit on my 03 CR2 & like the feel it provided across the rpm range. I don't think it actually added any HP, but feel it provided a better snap off the bottom with good torque through the rpm range into an added overrev. I tired a Boyesen & Vforce unit on an 01 CR250r & actually liked the Vforce over the Boyesen.

The Boyesen unit did feel like it provided a "tad" better off idle to lowend torque at the expense of a little off the topend. It felt like a trade off so I went with the Vforce since I ride primarily mx.
blackdiamond
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blackdiamond 5/1/2016 1:04pm
5/1/2016 1:04pm
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match it to the manifold to determine the final result. I will probably get around to doing that in a few weeks because I won't have the bike back from MXA until Thurs.
Underground 5/1/2016 4:12pm
5/1/2016 4:12pm
blackdiamond wrote:
I was surprised but it will actually go 68-70 miles per hour in fourth gear now! I didn't think it would be that fast on top.
Well that's faster than my pucker can tighten on an MX track, so I can't see that being a problem.

The Shop

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ledger
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ledger 5/1/2016 5:21pm
5/1/2016 5:21pm
If you don't mind me asking, who supplied the titanium bolts ? Also,may be a stupid question, but is MXA doing an article on your RC that we can actually get our hands on ? I would like to add that copy to my collection. Thanks.
blackdiamond
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blackdiamond 5/1/2016 5:39pm
5/1/2016 5:39pm
ledger wrote:
If you don't mind me asking, who supplied the titanium bolts ? Also,may be a stupid question, but is MXA doing an article on your RC...
If you don't mind me asking, who supplied the titanium bolts ? Also,may be a stupid question, but is MXA doing an article on your RC that we can actually get our hands on ? I would like to add that copy to my collection. Thanks.
Almost all of the hardware is from Racetech Titanium.

MXA took some pics of it last week and they are testing it at Glen Helen on Thursday for an upcoming feature but I don't know the time frame or which month just yet.
New to -4S-Joe 5/1/2016 11:34pm
5/1/2016 11:34pm
blackdiamond wrote:
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match...
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match it to the manifold to determine the final result. I will probably get around to doing that in a few weeks because I won't have the bike back from MXA until Thurs.
I've heard some guys say the Boyesen's better after being modified from some people, but most shops like V-Force, so I'm very curious to see what you find out in your testing.
Are you going to be testing any other engine parts or ignition settings?
blackdiamond
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blackdiamond 5/2/2016 12:34am
5/2/2016 12:34am
blackdiamond wrote:
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match...
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match it to the manifold to determine the final result. I will probably get around to doing that in a few weeks because I won't have the bike back from MXA until Thurs.
New to -4S-Joe wrote:
I've heard some guys say the Boyesen's better after being modified from some people, but most shops like V-Force, so I'm very curious to see what...
I've heard some guys say the Boyesen's better after being modified from some people, but most shops like V-Force, so I'm very curious to see what you find out in your testing.
Are you going to be testing any other engine parts or ignition settings?
They are all better when they're modified and perfectly matched to the intake manifold. Sometimes radiusing certain elements of the reed cage also yields a benefit, however I have not tested them back to back as of yet. For example, if you compare the 2003 to the 2004 OEM intake manifold, it is a massive improvement to use the 2004. It offers a much lower and straighter path into the crankcase. The same goes for the air box boot, the 2004-2007 has more volume and is an upgrade for any of those previous models. Really simple, inexpensive changes you can make by juggling the OEM parts from year to year will sometimes yield far more benefits than any fancy, bling-bling aftermarket bolt on parts could ever dream of.

We are definitely going to be testing more ignition settings and tinkering with a few other things, but I feel we are really close to a near perfect setting and at some point we might end up with too much of a good thing if we are not careful.
New to -4S-Joe 5/2/2016 2:26am
5/2/2016 2:26am
blackdiamond wrote:
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match...
I have tried both the Boyesen and a modified Vforce 3 but we need to do another dyno session after we mod the boyesen and match it to the manifold to determine the final result. I will probably get around to doing that in a few weeks because I won't have the bike back from MXA until Thurs.
New to -4S-Joe wrote:
I've heard some guys say the Boyesen's better after being modified from some people, but most shops like V-Force, so I'm very curious to see what...
I've heard some guys say the Boyesen's better after being modified from some people, but most shops like V-Force, so I'm very curious to see what you find out in your testing.
Are you going to be testing any other engine parts or ignition settings?
blackdiamond wrote:
They are all better when they're modified and perfectly matched to the intake manifold. Sometimes radiusing certain elements of the reed cage also yields a benefit...
They are all better when they're modified and perfectly matched to the intake manifold. Sometimes radiusing certain elements of the reed cage also yields a benefit, however I have not tested them back to back as of yet. For example, if you compare the 2003 to the 2004 OEM intake manifold, it is a massive improvement to use the 2004. It offers a much lower and straighter path into the crankcase. The same goes for the air box boot, the 2004-2007 has more volume and is an upgrade for any of those previous models. Really simple, inexpensive changes you can make by juggling the OEM parts from year to year will sometimes yield far more benefits than any fancy, bling-bling aftermarket bolt on parts could ever dream of.

We are definitely going to be testing more ignition settings and tinkering with a few other things, but I feel we are really close to a near perfect setting and at some point we might end up with too much of a good thing if we are not careful.
BD- I'm watching your build and learning. I plan to do my 2002 Honda CR 250. Problem for me is there is some pretty big changes from 02 to even 03 with the intakes. I also don't think I'm going to spend the money on a power jet carberutor. I'll use a standard PWK or a modified Mikuni. I don't think I can make the 04's Reed boot work with those carberutor's . I bought a 03 air boot which is supposed to have more volume than the 02's. Really curious as to what you find in testing the Reed blocks. I'm leaning towards the V-Force!
Emil_Andersson 5/3/2016 10:19am
5/3/2016 10:19am
blackdiamond wrote:
[img]https://p.vitalmx.com/photos/forums/2016/05/03/133809/s1200_DSC7776_Kyoshi_Honda_2_Stroke_Shoot_04282016.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/05/03/133810/s1200_DSC7960_Kyoshi_Honda_2_Stroke_Shoot_04282016.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/05/03/133811/s1200_DSC8099_Kyoshi_Honda_2_Stroke_Shoot_04282016.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/05/03/133812/s1200_MIN_1014_2.jpg[/img]








Sweet built BD, really amazing!
blackdiamond
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blackdiamond 5/3/2016 11:23am
5/3/2016 11:23am
rostocker wrote:
Dont you need this?? :woohoo: [img]https://www.motocrossshop.nl/media/catalog/product/cache/12/image/800x800/91fd56c95fdea5615f1a053520ebf6fa/2/5/25187.jpg[/img] https://www.motocrossshop.nl/tuning-parts/carbon-parts/twin-air/carbon-airbox-subframe/honda/twin-air-carbon-fiber-airbox-subfr-cr250f-06-07.html
Dont you need this?? Woohoo

https://www.motocrossshop.nl/tuning-parts/carbon-parts/twin-air/carbon-…
They only made those for the CRF250
rostocker
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rostocker 5/3/2016 11:27am
5/3/2016 11:27am Edited Date/Time 5/3/2016 11:21pm
Who puts the "F" after 250!? Blink
mtok77
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mtok77 5/3/2016 11:34am
5/3/2016 11:34am
rostocker wrote:
Dont you need this?? :woohoo: [img]https://www.motocrossshop.nl/media/catalog/product/cache/12/image/800x800/91fd56c95fdea5615f1a053520ebf6fa/2/5/25187.jpg[/img] https://www.motocrossshop.nl/tuning-parts/carbon-parts/twin-air/carbon-airbox-subframe/honda/twin-air-carbon-fiber-airbox-subfr-cr250f-06-07.html
Dont you need this?? Woohoo

https://www.motocrossshop.nl/tuning-parts/carbon-parts/twin-air/carbon-…
blackdiamond wrote:
They only made those for the CRF250
Cmt Compositi has a carbon airbox for the CR 250.
blackdiamond
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blackdiamond 5/3/2016 3:35pm
5/3/2016 3:35pm
mtok77 wrote:
Cmt Compositi has a carbon airbox for the CR 250.
I have been importing the CMT carbon parts for about a year and a half but no one has been crazy enough to order a sub-frame as of yet. They have actually done carbon rear fenders and side panels too.







2
FlaNard
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FlaNard 5/3/2016 4:26pm
5/3/2016 4:26pm
blackdiamond wrote:
[img]https://p.vitalmx.com/photos/forums/2016/05/03/133809/s1200_DSC7776_Kyoshi_Honda_2_Stroke_Shoot_04282016.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/05/03/133810/s1200_DSC7960_Kyoshi_Honda_2_Stroke_Shoot_04282016.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/05/03/133811/s1200_DSC8099_Kyoshi_Honda_2_Stroke_Shoot_04282016.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/05/03/133812/s1200_MIN_1014_2.jpg[/img]








RMRider1
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RMRider1 5/3/2016 7:48pm
5/3/2016 7:48pm
Straight up porn right there from MXA! Filthy!

Pit Row

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RMRider1
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RMRider1 5/3/2016 7:51pm
5/3/2016 7:51pm


blackdiamond
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blackdiamond 5/4/2016 11:50pm
5/4/2016 11:50pm
Here's another one...



ledger
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ledger 5/5/2016 12:33am
5/5/2016 12:33am
blackdiamond wrote:
Here's another one... [img]https://p.vitalmx.com/photos/forums/2016/05/04/134033/s1200_MIN_1151.jpg[/img]
Here's another one...



They better be good to her !! Cool pic bd.
Underground 5/5/2016 12:52am
5/5/2016 12:52am
Were they happy with the gearing and fork spring rate?
blackdiamond
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blackdiamond 5/5/2016 1:01am
5/5/2016 1:01am
So far so good, but we are going to Glen Helen next Thursday and that will be the true test.
barkhard696
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barkhard696 5/5/2016 9:52pm
5/5/2016 9:52pm
BD, a buddy of mine has asked about getting the C/F tank for his 05 CR. Kindly would you reach out so that might connect you two? My PM is unreliable at best. Thanks james.strawn@sbcglobal.net, 281-750-1705
Underground 5/5/2016 10:19pm
5/5/2016 10:19pm Edited Date/Time 5/5/2016 10:20pm
blackdiamond wrote:
So far so good, but we are going to Glen Helen next Thursday and that will be the true test.
Sure will but I was just giving those dudes shit & if any track needs firm fork springs, that is it. Remote lockout even!Laughing In hindsight for a lot of years they were right as the japs seemed to love a softer fork spring r.e.matching to rear.
Kudos to the photog also. Epic pics and jazzing.
I think this bike and thread also needs a place in the HOF bike builds folder Gibby
blackdiamond
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blackdiamond 5/5/2016 10:28pm
5/5/2016 10:28pm
barkhard696 wrote:
BD, a buddy of mine has asked about getting the C/F tank for his 05 CR. Kindly would you reach out so that might connect you...
BD, a buddy of mine has asked about getting the C/F tank for his 05 CR. Kindly would you reach out so that might connect you two? My PM is unreliable at best. Thanks james.strawn@sbcglobal.net, 281-750-1705
I just sent you a text, hit me up tomorrow and we will get it handled.
barkhard696
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barkhard696 5/6/2016 5:56am
5/6/2016 5:56am Edited Date/Time 5/6/2016 6:04am
Thanks BD. Super cool chatting with you!

>I think this bike and thread also needs a place in the HOF bike builds folder Gibby

If this isn't a HoF thred Al Gore REALLY DID invent the internet and I'm Jeremy McGrath.

BD, this project is so next level -- not only in terms of attention to detail and execution, coupled with elegance of engineering and machining solutions-- I find inspiration and information I shall be able to use for every build I'll ever do from this point on. High- or low- end budget, all can mine great stuff here.

GuyB, this is what a true HoF thred is made of, and by a very cool dude to boot.

slipdog
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slipdog 5/6/2016 6:08am
5/6/2016 6:08am
Slipdog likey!
rostocker
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rostocker 5/11/2016 10:38pm
5/11/2016 10:38pm
Hey Blackdimond,
Yesterday I mounted my triple clamp that I’ve been using for my 09-12 Crf 450 and last on a CRF250-14
It looks like the stem is 2mm short. Have you experienced the same thing or how did you do to fit your Neken?
blackdiamond
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blackdiamond 5/11/2016 11:54pm
5/11/2016 11:54pm
rostocker wrote:
Hey Blackdimond, Yesterday I mounted my triple clamp that I’ve been using for my 09-12 Crf 450 and last on a CRF250-14 It looks like the...
Hey Blackdimond,
Yesterday I mounted my triple clamp that I’ve been using for my 09-12 Crf 450 and last on a CRF250-14
It looks like the stem is 2mm short. Have you experienced the same thing or how did you do to fit your Neken?
You know, I honestly can't remember? The easiest fix would be to swap the steerer tube and use the one from the CR250. It's been awhile since I did that and I can't seem to find any notes on it.

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