HELP! frame questions for smart guys

[jgracing]

im looking to convert my 250r into a crf450 yz426...

but i dont really feel like going and buying a frame to make it work. everyone says they wont fit,, hmm well i bet the good oll boys wouldnt let that stand.. anyone know any tricks or secrets to use that would make one of these engines work for a stock frame? pm me please




2 curtis sparks race engines for sale 250r,265r

[bone705]

im pretty sure you have raise your top frame rails. i think you also might have to run a no link set up.

[nwi45]

I was wondering the same thing, because I plan on stuffin a thumper in mine next season. I just know I won't have enough money for a frame and a new DB engine. Are there any engines that aren't as tall to where you won't have to raise the frame rails? Thanks

[jgracing]

thanks man.. im handy with the welder lol... anyone else know much about doin this sort of stuff.... or does anyone know what engine would be taller?

[8dave3]

Local guy took a yz400f or whatever the 400 4 stroke is and put it in a 400 EX frame.He used one of my old LSR 250R swingers with no probs.

[zedicus00]

if yur stock frame is in good condition then sell it. take the money from it an whatever u was going to put into it an buy a frame to fit. that way u dont destroy another stock frame that sumone could put to good use.

[tholt]

Yeah you would more then likely have to go to a no-link and change the rails that run underneath the gas tank. I am fixing to build another frame to fit my drz400 motor that i put in my 250R frame but this is a pic of what i had to do. That first pic is in the middle of making it. the second pic is when i was finished. Just had to put on chain and oil lines and ride it.

http://www.jmrpowersports.com/pics/quad5.jpg

http://www.jmrpowersports.com/pics/Quad1.jpg


I have a couple more pics if u would liek to see. just e-mail me at Tholt@jmrpowersports.com



Tim

[Knips178]

so was fitting everything back together? did you have problems with the gas tank and the plastics mounting back up?

A "how to" on what you did would be great!!!

[tholt]

well i had to make all new brackets for the back of the gas tank so it would fit right and line up. I also had to make new seat tabs where the front of the seat hooks into. B/c i had to take the subframe off and reweld it back it on and had to change where the mounts went. and also as you can see i went to a no-link setup. I just got the measurements off a no link frame and changes my top shock mount so the carb and intake boot would fit past the shock mount.


Tim

[Knips178]

how high did you have to move the upper frame rails? I take it you made your own swinger right?

How long have you had it this way and has it held up ok?

[tholt]

I didn't really have to raise the frame rails. Reason why i changed them where the rails come up from the swingarm bolt, for the 250R motor they slant forward. If you were to look at a lonestasr frame for a crf motor, they are more vertical before they make there bend to go under the gas tank. I just got all of it finished about a week or so ago.

Yeahi made the swingarm as well. All i used right now was mild steel tubing and i have only gotten to ride it hard once. I jumped some pretty good sized jumps and came up short on a 60 footer a couple of times and no cracks yet.
i already have another frame here i am fixing to start working on so that i have a back up and i am probably going to make another swingarm out of chromoly so that it will be tougher. This was just kind of a test swingarm but i'm gonna run it as long as i can and see how it holds up. If it holds up good with the mild steel i used, i know with something like chromoly it would more then likely be unbreakable.


Tim.

[Knips178]

do you know what sort of hp numbers your getting out of that drz motor?

I wonder how close the drz400 motor is to a yz426f motor, height wise i mean

so you could have just cut the swingarm bolt mounts out and moved them back with out changing the upper frame rails right? But it was easier to just reshape the whole thing? I've often wondered how hard it would be to duplicate the stock frame with round chromoly tubing and build it for a crf or yz motor. Seems like if you just took your time and made jigs for everything it wouldn't be that difficult.

But what do I know

[tholt]

Yeah you could of just changed the swingarm bolt, but if you do that, you gotta remember to move your shock mounts and your linkage mounts to go with it. If you don't it will through your rear suspension all out of whack.
That drz motor is about the same height as a yz426 motor. I'm not sure what kind of hp numbers it has right now. I planning on running it on the dyno when i get back from the glen helen national. Its pretty strong but i only have hotcams in it, high compressin piston and a fcr carb off a yz426 on it. My motor is still stock bore.


Tim.

[Knips178]

Alot of great info Tim, Thanks alot.

I just wonder if I could modify my 89 stock swinger to work in that setup?? hmmm??

While I feel pretty confident with changing the frame and mounts, the swingarm fabrication is a little advanced.

good luck at the glen helen nationals. what class are you running?

[tholt]

aww no problem on the info. Just remember that more then likely you will have to go to a no-link setup or a cr500 setup. b/c when you put the motor in the frame the stock shock mount is right in line with the carb if you use the original swingarm bolt location. and like i said, just don't forget that with the linkage, if u move the swingarm you have to move the shock mount and lower llinkage mount for it all still to function correctly.

I tried to qualify at Loretto lynns last year in 265 B but i blew my motor up there when i had an R motor. head gasket blew and over heated it. I'm not running the glen helen national even though i would love to. I'm mechanicing for keith little this year so i gotta go t okeep his bikes together.


Tim

[Knips178]

sweet! So you work for LSR? or keith little personally?

give em hell

[tholt]

i think its really more keith personally. wish i had some more insight with lsr but its mainly keith.