BannedCR500Riders.com

Hello and congrats for this forum.

Looking around the forum i saw many different (and amazing) ways of making the conversion and especially the Y section and the mounting holes.

As i am about to start cutting my CRF 450 05 to receive a 500 96 i would like to ask...

Did anyone had significant problems (warping, bending or splitting) with his construction?

Could some of the modifications have been overengineered?

thank you.

I built a whole different cradle and Y section and made the mount plates longer than what most others do.

Warping? No. I had empty cases bolted in for most of the final welding. I heated the frame in an oven for less distortion. The last time I had the engine in/out, everything lined up perfectly.

Splitting? It's not running yet but I don't forsee any probs.

Overengineered? Yes.

there have been a small handfull of cases where frames fail, its almost always at the Y, and sometimes results in a cracked or broken frame sparr at the bottom of the seat. on my gen-3 I kept the factory weld angle instead to cutting it strait and doing a strait weld. also you want to keep as little tension on the frame as possible to reduce stress fractures and exsessive vibes.

i see... but i would love to see some pictures of these.


i have one more question...

since round tubes can withstand more force (and from different angles) than square tubes, wouldn't it be nice to change the entire underside (until the Y section) with round tubes

This has been talked about before. Even though round tubing is/could be structurally strong enough, most people frown on the fact that it doesn't look factory (doesn't match the rest of the frame).
I looked at many different builds before I chopped into mine. I've seen where solid square stock was used, one builder did use round bar (it looked cheezy), square tubing is the norm.
Welding hollow tubing to hollow tubing requires less effort. Welding solid stock to hollow tubing takes more finess. It all depends on what materials you have available and what you can work with the best.....If you do it yourself and there aren't any strength issues, then most of us here will give you a big .

Some frames require minimal modding while 125s require a new cradle.

It really depends on what you want your bike to look like as well as how much effort you want to put in on the conversion.

CR500R7 wrote:It really depends on what you want your bike to look like as well as how much effort you want to put in on the conversion.

To me the gen 4 250F frame is the easiest to to convert, and still look OEM ( aka ..the best )

Gen 3 SH CR500AF (AKA.....Aj special)




Where the spars cracked

My gen 3






I have done a few of them with no failures yet

aj special ? did that cost extra

is that a sh cr500af with crackt frame spares also is it a crf 450 or a cr 250 gen 3 for a shonda the welds do not loke that great i think why spend all that money why not make one i have 0 pounds in my build saying that i have 600 pound wat i payed for my cr 500 the crf 450 i uesd hows me nothink has i boght it with a bad main end bearing for 350 pounds and hi habe made over 450 pounds seling the engine in parts so in the end wwill not stand me more than 1500 pound

AlisoBob wrote:
To me the gen 4 250F frame is the easiest to to convert, and still look OEM ( aka ..the best )

That looks really nice man.

Bob if that is your bike, it looks great.
A bad conversion is a bad conversion regardless of which gen frame is used, it all depends on who did the conversion.
I am sure someone can make a shitty GEN 4 non factory conversion.

I personally thing the cast Y is the only good part about a gen-4 conversion. otherwise, I think the fact that gen-1 to gen-3 cr250 frames are cleaner because the lower mounts don't need to be touched.

I agree.
The less you F@#K with something the better it always turns out with less effort and time.
The only way to go.

Wheelie-Gene wrote:

AlisoBob wrote:
To me the gen 4 250F frame is the easiest to to convert, and still look OEM ( aka ..the best )

That looks really nice man.

Thanks Gene.....

CR500R7 wrote:Bob if that is your bike, it looks great.

To be quite honest that looks like Honda made it, but only a lot better looking WELDS.
That looks really neat, great workmanship.

HEY, WAIT A MINUTE! where is the BANNED off the ignition cover, are you hanging out with the opposition now.

pstoffers wrote:Gen 3 SH CR500AF (AKA.....Aj special)
Where the spars cracked

and you kept (and repaired) that frame after that!!

By the way does any one know how to weld Aluminium with tig?

I am an hobby welder myself and now that i am trying to calibrate my tig weld (current, nozzle size, frequency etc) i have a heck of a problem making a good weld (i can make quite good steel TIG welds but never tried alu)

i am using some AluMg rods on an old YZ swing arm but the weld does not spread around.... it popes up like a mushroom and it makes very weak welds (obviously)

since the frame is the 6061 (ALMgSi) could that (alone) be my problem?

thank you again.

p.s. my machine has the potential to weld aluminium (AC pulse 200A) but it is not a top self machine.

I can't for the life of me, work out why the frame spars would crack on top of the spars.
You would think landing off of a jump it would bend in the middle towards the ground splitting from the bottom upwards.
Just like the bike that broke in half , somewhere on this site is pictures showing what I mean.
Unless these are just vibration cracks.
Anyone with the knowledge to be able to explain this, please do.

I would assume that the Y and cradle were "made to fit" and may have stressed the frame in that direction. you add vibration and and some crazy hill climbing action and you have some hardcore stress fractures.

sonic22 wrote:By the way does any one know how to weld Aluminium with tig?

I am an hobby welder myself and now that i am trying to calibrate my tig weld (current, nozzle size, frequency etc) i have a heck of a problem making a good weld (i can make quite good steel TIG welds but never tried alu)

i am using some AluMg rods on an old YZ swing arm but the weld does not spread around.... it popes up like a mushroom and it makes very weak welds (obviously)

since the frame is the 6061 (ALMgSi) could that (alone) be my problem?

thank you again.

p.s. my machine has the potential to weld aluminium (AC pulse 200A) but it is not a top self machine.

what gas are you using? what rod, exactly? there are many grades of al/mag alloy. On my mig, I believe I used 4340 with an H25/argon mix.

sonic22 wrote:

pstoffers wrote:Gen 3 SH CR500AF (AKA.....Aj special)
Where the spars cracked

and you kept (and repaired) that frame after that!!

I sure did........