ed500
New Member
Posts: 12
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Post by ed500 on Mar 4, 2006 11:00:11 GMT -5
I bought a ratty 81 SR that I was going to restore but I got sidetracked. It turned into a street version (sort of) of the Aberg MX bike. It's got a YZ aluminum tank, a YZ seat and the swingarm is from a 78 RM125 MX bike. Everything is pretty solid. I cut off every piece of unnecesary metal to lighten it up. The exhaust is hand made by me. The motor is completely stock. Pic are here: www.angelfire.com/planet/edgo897/thumperEd |
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Post by hopwheels on Jun 24, 2006 11:58:22 GMT -5
That's sweet Ed. I'm trying to fit up a '79 RM250 swingarm to an XT frame. What mods did you have to do to fit that swingarm? Thanks for the pics. Looks like a fun ride.
Gary
Hopwheels
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Post by G Man on Jun 24, 2006 16:08:22 GMT -5
Geez, I like that too! Nice job.  G Man |
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RD
Full Member
Posts: 176
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Post by RD on Jun 25, 2006 4:34:23 GMT -5
Hi Ed
Thats cool, I like that you haven't gone cafe like most of us.
Cheers
Rich
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ed500
New Member
Posts: 12
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Post by ed500 on Jul 8, 2006 9:39:01 GMT -5
To get the swingarm to fit I got rid of the needle bearings and replaced them with polyurethane bushings. I just bought some universal bushings and filed them down to fit. Since it has only a couple of inches of travel in the rear they should last a long time. Everything is good and tight on the bike. The '78 RM125 arm has almost exactly the same dimensions as the SR arm. The bottom shock mounts are a hair narrower but it doesn't affect how it functions. I had to file out the swingarm axle slot less than 1mm and then play with spacers to get the rear wheel situated. I used the stock SR chain adjusters and brake arm. It turned out a lot better than I ever thought it would. People are always asking me if I want to sell it.
Gary, I'm currently restoring a 79 RM250. I raced one of them back in the day. I think you could weld over the swingarm pivot hole in the XT frame then drill it out to the RM pivot bolt size. That would be the easy way to get the RM arm on. What is the diameter of the XT pivot bolt? The 79/80 RM's had pretty swingarms, it will look good back there.
Ed
Ed
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Post by frankyb on Jul 9, 2006 7:03:07 GMT -5
try replacing stock sr triple clamps with 79/80 alloy clamps. these are wider between the legs but have a lot less offset between legs and stem. benefit is slightly lessened rake and trail. lace 18 inch rim to aircooled rd disc hub (PCRA legal) to give better tyre choices. this should help a lot with the front end push,and get you heading towards your ideal set up. an xt or tt 500 rear wheel of the same era is a no mods fit, but only has a drum brake. this setup is lighter and has dirt bike style rimlocks, which will help at wakefield where we always seemed to get wheelspin on the off cambers. oh by the way the t clamps at the top are xt/tt 500. we always had a better result with narrower tyre setions, from memory 110 rear and 90 or 100 front, the whole thing just seemed to tip in easier. the konis at the back sound good to me, but they were all you could get once so im probably biased. all the mods we arrived at all seemed to be low dollar, so that kept the fun factor alive. just rember when youre driving home from a race meet and you cant wipe the grin off your face, that irrespective of where you finished, youve won. cheers franky b
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Post by kentrex on Aug 21, 2006 4:47:40 GMT -5
Hey Ed....Nice bike....do you wanna sell it?? ;D
Ken
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Post by StewRoss on Aug 22, 2006 3:31:05 GMT -5
Hi Ed, What capacity is the yellow YZ? I used to race MX on YZ's...a few years ago now...one I had was a YZ465G...these were the best open class bike of the time...with plenty of power. Our bikes were red and white...on these you either learnt throttle control or crashed  In '81 I went back again to a 250...YZ250J...I gave up in '83 after 7 years of racing MX...excellent fun! I keep looking at the 450's now, but I probably couldn't stand the pain anymore...still like to ride one though....just to see..... SR |
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ed500
New Member
Posts: 12
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Post by ed500 on Aug 22, 2006 11:07:37 GMT -5
My YZ is a 1978 400cc. I got it last year and at that time it still had the original tires and chain and sprockets. It's still on the first piston too. It should be in a museum. I had the rear shock rebuilt by Sage Suspension in Denver CO, and I put 1980 YZ465 forks on it. I ride it every Sunday morning for about 45 minutes at a local track and then I'm done. It does scare me at times. Yamaha pretty much always had the best open class motocrosser back then didn't they? Back then I raced a '76 YZ125, a '78 RM125 and a '79 RM250 too.
Ed
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