ATC 500R Swingarm Bolt & Other???

[sand slinger]

I am currently in the process of putting an 88 cr 500 engine into an 85 250R frame. I have been looking at this sight for a while but I finnaly joined today. The conversions on here are amazing and they all keep me motivated. I have looked at all of the pictures of the 500s and I am wondering if you guys put the swingarm bolt through the engine where it goes on the dirtbike or used some other method? I have already cut the bottem of the 250R frame out and i was going to use the cradle of the 500 frame but It isn't seeming to work out. If I try and put the swingarm bolt through the engine the engine hits the bottom cross bar of the frame. I think I am going to end up making new frame rails like pro hemi did. I also was wondering if you guys cheated the engine to one side for sprocket allignment? It looks like the engine needs to go to the left a little to get perfect allignment. Thanks for any help and I am willing to listen to anything anybody has to say about the conversion and or look at pictures.

[Billy Golightly]

On my 500 I totally cut out the bottom frame rails and heavily modified that bottom cross rail that the shock linkage mount is attached to. I did run the standard 250R swingarm bolt through the back of the CR500 motor, and thats the only way to do it and have it be right with the sprocket and swingarm pivot alignment.

As far as the front and rear sprocket alignment, slide the CR500 all the way over to the far left with all the dust caps and seals in place, thats pretty much exactly where it has to sit. You can make a spacer to shim the space left on the right hand side, I made one out of aluminum for mine.

[sand slinger]

Did you cut the front part of the tube off and leave the back part with the linkage mounts? I was thinking of cutting the tube down the middle and then turning the piece around and welding it back in for reinforcement. What did you fab your new craddle out of? Also did you use the same mounts on the frame for the engine brace that goes to the head?

[Billy Golightly]

Checkout the little link right under the picture in my signature, its got everything covered in detail for my build.

I more or less cut about half of that tube out, and put in a piece of angle iron so the bottom corners of the case could fit down in there. I originally just flattened the tube but it wasn't enough, its got to be significantly notched in such a way as the case can fit in the centerline of that tube, or its got to be removed completely. if I was to do it again I would probably cut that entire porition of the frame out and remake it in a bend but have the shock linkage mounts positioned in such a way that they were in the exact same placement so as to not change the linkage ratios any.

The new cradle was bent out of 1 1/8in 4130 Chromoly, .065 wall. I'd recommend something a little bit thicker as I have had some issues with my bottom mounting tabs cracking out around through the tube itself. Something like .083 would probably be good.

I made a new head stay bracket setup. I used the original mount on the CR500 head, but made new plates to bolt it to the existing head stay mounts on the 250R frame.

[sand slinger]

Wow Billy I just read through your whole build and it took me like an hour and a half. I cant believe how much work was actually involved, great job. I need to press on but know I am starting to second guess my purchase and chopping up of a perfectly clean 88 500. And also chopping my babies bottem end out!! All the sudden the spyhnx cylinder might not have been such a bad idea. ha ha Well I am past the point of no return now. If anybody else has any pictures of how they modified the bottem of thier frame I would love any ideas. At least I have the 500 frame and I might try to put some of its remaining pieces to use.

[KASEY]

i never cut the cradle in my frame at all,,, its still all original.. it took me longer to get it in ,, but its been in for 6 years without a single problem,,

[jeffatc250r]

I welded a strap across the bottom shock link mount to keep its location, then cut the cross rail that its attached to out, trimmed the ear of the mount back like an inch or so, then welded in a whole new tube. Piece of cake!http://i462.photobucket.com/albums/qq350/jeffsatc250r/DSC01759.jpg

[jeffatc250r]

http://i462.photobucket.com/albums/qq350/jeffsatc250r/DSC01760.jpg

[jeffatc250r]

http://i462.photobucket.com/albums/qq350/jeffsatc250r/DSC01758.jpg

[jeffatc250r]

I didnt bother trying to graft the 500 cradle in, this came out much better and i am very happy with the results. I remember the 2 frame rails gave me a hard time to make with the bender i used. Dont be discouraged, it will all be worth it in the end! I think you can get away with flattening out the stock bottom cross rail to get the bottom of the motor to clear, but i didnt like the way it looked, so i went with a whole new piece.

[KASEY]

did you sleeve the joints or just butt them and weld?

[jeffatc250r]

I put a solid piece of round stock about two inches long in every joint, leaving a half inch exposed in the middle of the two joining rails and welded off of that, just have to wrestle with the last two ends a little bit by stretching the frame enough to slip the ends into the frame tubes. I would be kinda leery about just butt-welding them, could become a weak link. The cross rail was just butt welded, then welded to the welded on 3/16 thick skid plate, nothing will ever break.

[sand slinger]

Thanks for all the pictures jeff. I like the looks of how you removed that linkage mount bar and just replaced it. I was wondering how kasey fit the motor in with no modification. Do you have any pictures?

[KASEY]

well ,, i have taken so much crap about the way i put mine in i don't even waste time posting pictures anymore,,,,, mine has been ridden pretty hard for 6 years and have had not a single crack in the frame,,,, next week ,, some of the OTC guys will be at glamis and i am going to ride with them for 3 days,,,, that will give them a chance to look it over,, i can say it took along time to get it placed where the exhaust cleared,,, the bottom cleared ,,,and you can still get the plug out and the topend off without pulling the motor out,,,, i have ran a 6+ swingarn from the begining,with a 350/400lb progressive spring , so there is a hell of a lot more leverage on the frame too without a failure,,,it get ridden!!

http://i44.tinypic.com/2ihnx2r.jpg
http://i39.tinypic.com/2lukxu.jpg
http://i40.tinypic.com/sd1cag.jpg
http://i40.tinypic.com/2heis7c.jpg

OF COARSE THE SUSPENSION DOESN'T GET MUCH USE WHEN THE WHEELS ARE ALWAYS OFF THE GROUND!!!
http://i40.tinypic.com/dzz0q0.jpg

[NOS_350X]

Sand slinger Come on out to Rasor Rd, for the SW Trike Rally, its the 16-19 of jan little late notice.

http://www.3wheeler.org/vb/showthread.php?t=33221

http://www.3wheeler.org/vb/showthread.php?t=35469

[sand slinger]

Would love to come but i am on call that week and cant be that far from work. Do you live in Fresno, and do you go to Sand Mountain?