Uncle Crackers Gen 3 A/F Conversion

Building Tips, Suspension Set Ups, Conversion Parts .... Build to your Heart's Content!
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pstoffers
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Post by pstoffers »

mocr13 wrote:I am working on a 2003 cr250 to 500 conversion and found this about jacking the frame,my question is I have done some searching and I saw one person jack from where the swingarm bolts in, to the down tubes and spread that way(horizontal),but in this post it sounds like people are jacking from the top down to the lower tubes and spreading that way(vertical), (but I could be wrong as no pics and my simple mind has trouble comprehending without pics) so which is the best way? which gives the best clearence? any help would be greatly appreciated as I am interested in this metheod,compared to cutting the cradle! Thanks mocr13

Do it like this
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Roostius_Maximus
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Post by Roostius_Maximus »

nice pic find, i have almost every pic i've seen on the net on a hard drive, just not here today.
I did the same thing, had my frame sooty with a tiger torch, but Pauls MR Heater sound alot nicer to work with!
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AlisoBob
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Post by AlisoBob »

I like the angle piece thats 45'ed on the box tubing. I didnt think Paukie was that white.
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pstoffers
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Post by pstoffers »

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dubious01
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Post by dubious01 »

thanks for sharing this invaluable info. The 450 fucked frame is going to be used as salvage / garbage. I bought a 250 frame.

What are you guys doing with the airbox on the 02-07 Cr250r conversions?
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pstoffers
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Post by pstoffers »

dubious01 wrote:thanks for sharing this invaluable info. The 450 fucked frame is going to be used as salvage / garbage. I bought a 250 frame.

What are you guys doing with the airbox on the 02-07 Cr250r conversions?
You don't have to do anything.....
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Roostius_Maximus
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Post by Roostius_Maximus »

clean it :lol:
dubious01
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Post by dubious01 »

awesome!
I can't see whay anyone would bother with any conversion but a cr250r chasis then. It has the best rads to modify, with the clearances on the tanks already, and only the waterpump inlet spiggot needs changed.
No Y movement, no tubes replaced, 2 motor mounts that fit stock, makes it so much easier to have consistent motor placement, etc etc ....simple!


I cut off the front motor mounts, extended the cut up into the Y, to make it easier to jack, jacked the frame in like 2 hrs last night, and am doing the Y mod like Pstoffers.
I never used any heat.
I got most of the Y gouged out, and a 4" pipe 1" long that needs to be cut and bent to fit. then ready to weld.
This a is a true conversion that would take about 3 hrs to convert the second time around.

I am considering selling the CRF250 chasis, this is too easy!
dubious01
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Post by dubious01 »

so what pieces to not interchange from the 02 450 chasis, and the 02-07 CR250 chasis?

I'm hoping all the linkage and swingarm are the same?
rear shock?
fuel tank ?
seat?

Obviously I will need a subframe, and airbox for sure.
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Roostius_Maximus
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Post by Roostius_Maximus »

450 tank is wider and taller, shrouds swap, rads can work, seat i believe is different
shock, pivot bolt and swingarm should go no prob
dubious01
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Post by dubious01 »

hmm, I'll go check it all out. I hope the linkage is right.
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Roostius_Maximus
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Post by Roostius_Maximus »

i've bought 450 swingarms to run extentions on, the plastic clip for the brake line is different pretty sure the rest is the same
dubious01
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Post by dubious01 »

Roostius_Maximus wrote:i've bought 450 swingarms to run extentions on, the plastic clip for the brake line is different pretty sure the rest is the same

Thanks! Im pretty stoked !
kibler
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motor mounts

Post by kibler »

Where did those upper motor mounts come from? I could use a couple of them.
Kibler.
mxcrazy
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Post by mxcrazy »

Contact pstoffers dude, he posted a couple of replys up. He has a 'sticky' post too with all the bits he does listed.
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Roostius_Maximus
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Post by Roostius_Maximus »

UPDATE:

I bought this bike last year with the intent of catching hoonfest, didnt make it there.
Al Gava packed it up and shipped it to ND for me!
I got it together friday night, started at 9pm and was done by midnight with a little front fender and APT smartcarb upgrade acomplished also.

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It rained sunday but we had decided to ride. Got 1/2"while we were out, it was good.

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Saturday in 79f 65% humidity I lit the beast!
The bike doesn't like choke at these conditions.
It fired up good, set the idle, then proceed to break in this new Wiseco equipped top end with some tire annihilating wfo runs down the road, hahaha.

This bike just got home from California Thursday evening, I put it together with it ready to go by midnight Friday.
It's in a gen3 250 frame, the big billet carb cleared the chassis everywhere, cable worked once I clipped 1/4" off the housing like summitboy had run into last week with his unit also.
The clamping flange is not like a cast carb but has a machined ring lower than the other portion to let it grip, could be better.
From where it was set I richened it a click of the metering rod, it's feeling good, excellent in fact. I would like a pinch more fuel up top which requires a different rod, I expect to be certain of this in the cool September riding.
I put just over an hour of actual riding on the bike once I was done fiddling with fresh assembly things like lever positions, etc.

Carb pulls smooth and clean in low gear, doesn't load or get fumbly when geared too tall like trying to get moving in 3rd from barely a rolling start.
Deceleration is better than the pwks from my experiences. They require more fuel metered to keep them in the safe spot on decel than what they actually need for acceleration. Keep in mind that I was riding it to over exemplify the requirement most guys have. I pulled the gears long as possible and decelerated for the same with picking up throttle to see if it would catch up smoothly and it did. Obviously I can't speak for it running hot or cold, i didn't spew any water and I rang the snot out if it in decently tight bush with an 8mph breeze.
The bike has stock porting, stock reed and boot, stock ignition, close 1990 style trans, 14/49 gearing, a 110 tire and a fatty pipe. I chose the fatty from my wall of pipes after seeing the immaculate condition of the stock pipe the bike came with. The stock one is now in the archives.
There's a big storm building in the west, we'll see what tomorrow brings but I'd like to get a few more hours on it, not that I need to tune it at all but I just want to ride the dang thing!!!

I need to change the bars to something lie a CR bend for the ATV style ones on it, swap a set of my wheels onto it with an M5B, and mix some more fuel!

I'm running 91 pump premium with ethanol.

On a scale of 1-10 with the stock PJ being a 1, the PWK at 4, the 38mm smart carb comes in at a 6 with the pulse injected pwk at an 8.

Setup, after purchase parts required (possibly 1 metering rod at 15$), and ease of tuning is going to put these carbs on top of everything else out there.

I will be pulse injecting this one yet.

I leaned it a click when it was raining on our ride sunday, low end it was snappy but smokey. Don't get me wrong tho, it runs good.
I've always looked at the carbs as rich if they don't need choke to start, and I didnt, or should I say couldnt start it with choke.

Since the body of the carb is taller and the slide holds the cable lower you need to remove the cable from your throttle housing and cut 1/4" from the housing. I did and had a tap handy so I deepened the threads also, not sure that needed to be done. From here I have perfect adjustment.

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