Justin's Gen 3 A/F conversion

[Nomadic Cycle Racks]

Yesterday I started out the day by tearing down the '97 CR500 and parting it all out. This took me oh, about 1.5 hrs. Later in the afternoon I started wrenching on the 250 and by the evening I had the front engine mounts whacked and the 500 sitting in the cradle. This is where I stopped at 10pm about 6hrs. solid wrenching time...

Before I started the metamorphosis of the cr250 I am thinking to myself, "How can I just tear apart a perfectly good 250?" Then miraculously, a hilarious thought, maybe on the brink of a hoon motto, would lighten my soul and take away all doubt.

"A 250 is just 250 too small"

Here are some pics of the project thus far. Pardon the blurry ones. My camera freaks out with low lighting.


The steed before the speed...




Oh whats that, a 5 hundy in there?!


The motor looks like it hangs to more of the left side.


CR125 spacers...


More prep work to do. Shan, I need the headstay and front mounts post haste!

[britincali]

[dannygraves]

VERY

[ShanMan]

shipped today my brutha! Keep the momentum Justin...you will be roostin' in record time.

[AlisoBob]

shipped today my brutha! Keep the momentum Justin...you will be roostin' in record time.

X2!!

Good progress in 6 hours... Keep it going!

[Nomadic Cycle Racks]

The engine mounts and head stay came in today so it was back to work. What a bunch of filing, cutting, marking, bending and guessing today. I worked my ass off for another 6 hours today and feel like I'm spinning my wheels going nowhere, but it's progressing...

I had to make one of those handy dandy engine jigs I've seen before. So simple yet so helpful when it came to bending the cradle. As you can see from the first pics, my frame needed to be bent forward about 3/8" to accept the engine mounts.

Not pictured were other modifications I had to do as well:

1. Grind the frame near the right peg
2. Pound clearance for the water pump

Currently the water pump rests against the cradle. I think its okay.

All in all, most of the mounts lined up. What a trip this is...With the frame bent forward and engine in, (swingarm bolt and bottom engine bot in), the front engine mounts will not quite fit between the engine and inside of the cradle like they are supposed to. So I used a stock Honda Civic scissor jack to try and open it up a bit. The jack feels its about to give though and it's not opening up more then 1/8" like I need.

Does anyone have any suggestions? The cradle only needs to be opened up 1/8".



















Has anyone mounted their coil like this? It seems is would work if I drilled another hole in the bottom mount.

[AlisoBob]

Too narrow.... thats a new one. You could always spot face the engine mounting lugs a little bit..

As far as the frame? GO SLOW! Let it sit for a day, add a little heat.... the key is to coax it, not force it.

Your getting there..... GOOD JOB!



The Gen 3 I did had about twice as much to move. This looks about like Crackers frame did. Give it time...

[pstoffers]

This is how I did mine.

[Uncle Cracker]

This the same as my Gen3. I used a jack just like you are doing. I walked the jack up and down from the "Y" down the water pump area. I spent about a half an hour working up and down this area. Once you figure out the spring back of the frame, you will get a feel for the amount of force you need to use. Your in a better situation than I was due to the jig you are using, I had to stretch and then put my motor back in to check for clearance.

[Nomadic Cycle Racks]

After 10hrs. of beating, grinding and hooning on the frame, I finally have it all welded up. The engine jig was very handy in this process.

The tolerances between the frame and water pump and exhaust flange were the most tedious to perfect. Tedious to say the least!

To make ample room for the pipe flange, I grinded, sanded, and beated on the underside of the Y, eventually cracking the weld seam. It seemed to be a good thing though. This enabled me to continue clearancing for the pipe flange. The two halves happily curled over eachother, helping the process a lot.

How did I get the radius on the inside of the cradle you ask? - Freehand hole sawing is the trick. A dremel tool cleans up the inside edges well to accept the fillet-O-tubing

Also, notice the tubing on the inside of the Y. This is 1 1/4" 1/8" wall T6. Notice how the pieces run perpendicular to the cylinder head, not the frame...

If you can't tell, I copied Zerofear's interpretation of a good conversion...looks somewhat factory.

This seemed like the best route to go about on the conversion...

Modify the Y, but leave it in its place.

[Nomadic Cycle Racks]

If you're wondering why I kicked the gussets forward a bit, it was to make room for the rads.

[Nomadic Cycle Racks]

Only one coil mount was welded on. The top mount was an existing tab used by the servo mechanism for the CR250's powervalve.

Not pictured, I painstakingly extended all the CDI wires. Each wire lengthened 8" to mount the CDI behind the numberplate in its stock position.

Every solder joint was individually shrink tubed, then collectively shrunk together. Very clean.







Green sticker baby!!

[AlisoBob]

Good job coaxing the cradle.

[lewisclan]

looks nice man

[HrcRacing]

Lookin' good!

[ShanMan]

really nice Justin! Obviously, you are a weldin' fool, because those "rows of dimes" look sweeeeet man!

[Nomadic Cycle Racks]

Here is a good shot of the rad mod.

I didn't like how it came out the first time. Originally I salvaged the stock 90 degree downspout on the rad thinking it would be nice to save the outlet with the lip on it. But the 3/4" outlet and 7/8" water pump inlet didn't match, nor could I find a piece of rad hose to reduce from 7/8" to 3/4" in the length I needed.

So I opted to go with 1" 16ga. T6. Granted this is larger than the water pump O.D., but this would ensure proper coolant flowage. This also enabled me to use the stock rad hose .

Notice the pie cut, (per Bob's recommendation) on the smaller outlet. This is much needed for jug clearance.

[Nomadic Cycle Racks]

The only thing half-ass about any Gen 3 conversion is the exhaust, (unless you wanna pop for the SH setup). I tapped a hole in the sub-frame and used the factory 250 rear pipe mount for my rear-most silencer mount. The front silencer mount is a direct bolt-on.

Yes, there is no rear pipe mount. But its pretty damn stout. I don't think it's going anywhere.

Note the shrinktubing on the kicker. The kicker would slightly touch the frame and eventually wear it down so I decided to take care of it.

[Nomadic Cycle Racks]

Everything went together pretty well during the build. No major hiccups or re-gringing on the welds. Tolerance is very close in some parts but thats how these things go!

Here she is...the lady in red.

Project Started 1/21/07

Finished today, 2/1/07.

...Not bad for working out of a short bus garage.

All in all I estimate the project stole 35 hours of labor from me. Well worth the outcome. And the price is right too! After selling everything from both bikes, and keeping copious records of all expenses, I have an investment of $2525 into the entire project...not too shabby!

[eyesky2002]

Looks great!!!

[AlisoBob]

Note the shrinktubing on the kicker. The kicker would slightly touch the frame and eventually wear it down so I decided to take care of it.

Looks great!

[sabreguy]

Bitchen!!!

Looks real good and for $2500 it's even better!!!!!

[iggys-amsoil]

Note the shrinktubing on the kicker. The kicker would slightly touch the frame and eventually wear it down so I decided to take care of it.

You can take the kicker gear out and offset the gear and splined shaft. Mine bearly clears the pipe now but deff doesn't rub or touch it.

Its a choor but worth it.

Nice job

[Nomadic Cycle Racks]

I tried moving the kicker toward the pipe more. This won't work in my situation. The kicker will contact the pipe because the spline, not the kicker mechanism, has a little play in it. This configuration works better for me.

What I meant to say is the kicker MIGHT wear the frame. When the kicker clicks into position, it just barely makes contact with the frame and is totally rattle free at this point with the shrink tube.

[/quote]

[Nomadic Cycle Racks]

Oh nevermind, I get it. Ya sounds like a chore for such a little improvement. Maybe I'll do that when I need a clutch.