Gen 3 250 Build

maddog1927 · Post by **maddog1927** » April 22nd, 2015, 6:53 am

My 125 build turned out nice, but too twitchy for the dunes.

125 Build Here:
http://www.bannedcr500riders.com/board/ ... highlight=

I did an "algava" on a '03 250 frame, and traded it for a 250 that had been started but not finished.

Algava Build Here:
http://www.bannedcr500riders.com/board/ ... highlight=

I am now doing a 250 build with a http://www.conversionparts500.com/ billet wye and Paul's cradles.

maddog1927 · Post by **maddog1927** » April 22nd, 2015, 7:34 am

Replacement of the cradle is not necessary, using the OEM cradle would have been more straight forward, and even the lower motor mounts are a perfect fit on the 250, but previous owner had already cut cradle beyond limits to use the CP wye.

Dug out the cradle sockets, 4.5" grinder wafer blade, hammer, chisel, air grinder with a near worn out blade (small to get in tight).

Trimmed the replacement cradles to fit, band saw, 4.5" grinder wafer blade. Cut too big then sneak up on it 1/16"- 1/8" at a time.

Cleaned up weld areas with bead blaster, I will put the engine in to make sure everything is good, then take to welder:

Notes: The jig that I made with the headstay tab has been very helpfull. The 250 frame uses 125 swingarm spacers for 500 engine fitment.

Anybody got some NOS David Bailey graphics?

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » April 22nd, 2015, 10:53 am

Very nice.
I have one similar I should fix that way.

maddog1927 · Post by **maddog1927** » April 24th, 2015, 7:22 pm

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Welder said he liked the way I preped / Cleaned it. I like the way he welded it.

maddog1927 · Post by **maddog1927** » April 25th, 2015, 7:18 am

I'm going to try for a "spar tank" reserve fuel system.

Drill top tank bolt socket into frame pocket, this will be the vent.

Make a "banjo" bolt for top tank bolt / Vent.

Install weld on barb fittings on lower/inner face of spar. I won't be able to use existing holes because they interfere with pipe / carb.

Create passageway from down tube to spar via hoop that connects down tube to spar. I will need to drill 2 holes to create this passage, then weld the surface hole.

Weld oem air passage holes.

PSI/Soap for air leaks. I will find some more on the oem welds.

I had my kindergardener draw a schematic:

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5/16" Weld on barb (ebay)

5/16" petcock (ebay)[/img]

5/16" Barb Tee (ebay):

Cant find a 5/16" 90 degree filter. Here is a 1/4":

[/img]

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » April 26th, 2015, 6:51 am

I can't remember if it was my gen3 or gen1&2 bikes, but don't the tubes also vent into the steering stem cavity?
Good idea tho, I also looked at doing it before but lost ambition. Making a fuel tanker swingarm for a guy soon too by the sounds of it. Pulse pump to lift it back to the tank.

maddog1927 · Post by **maddog1927** » April 26th, 2015, 5:15 pm

Roostius_Maximus wrote:I can't remember if it was my gen3 or gen1&2 bikes, but don't the tubes also vent into the steering stem cavity?
Good idea tho, I also looked at doing it before but lost ambition. Making a fuel tanker swingarm for a guy soon too by the sounds of it. Pulse pump to lift it back to the tank.

My previous '01 250 and my '02 125 are open spar to steering stem. My '02 250 is not. On the 125 I built a sleeve with o rings to isolate. Was not worth the effort.

Sandblaster · Post by **Sandblaster** » April 27th, 2015, 7:09 am

Beautiful welds... I think MPS is looking for lessons

Just curious, are you gonna heat treat your frame?

maddog1927 · Post by **maddog1927** » April 27th, 2015, 8:19 am

Sandblaster wrote:Beautiful welds... I think MPS is looking for lessons
Just curious, are you gonna heat treat your frame?

Thx on the welds.

No on the heat treat.

Kuma · Post by **Kuma** » April 27th, 2015, 12:29 pm

maddog1927 wrote:
Roostius_Maximus wrote:I can't remember if it was my gen3 or gen1&2 bikes, but don't the tubes also vent into the steering stem cavity?
Good idea tho, I also looked at doing it before but lost ambition. Making a fuel tanker swingarm for a guy soon too by the sounds of it. Pulse pump to lift it back to the tank.
My previous '01 250 and my '02 125 are open spar to steering stem. My '02 250 is not. On the 125 I built a sleeve with o rings to isolate. Was not worth the effort.

I usually just go a little more getto and carry one or two gatoraid bottles with gas in my backpack

, you sould be looking at using those spars at nitros tanks

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » April 27th, 2015, 12:57 pm

thinking that they might not hold 900psi

Jercs · Post by **Jercs** » May 2nd, 2015, 10:50 pm

Maddog1927,

Looks like you're building a great bike! It's awesome to see the different builds.

Thanks for sharing!

CP500
ConversionParts500

BannedCR500Riders.com

Gen 3 250 Build

Gen 3 250 Build