79 XR500 VINTAGE MOTOCROSSER BUILD

I am building a 79 XR500 mx'er and was wondering if anybody has any tips tricks or ideas that they have used on the suspension or asny custom work they have done on the XR500's. Alot of my friends are getting into vintage racing and so i want to be different from the rest and not ride a 2-stroke like everyone else does. Anybody made a custom swingarm?moved the rear shock mounts on a stock swingarm?  Any and all help, knowledge, or information would be greatly appreciated. Here is a pick of the project bike and i will update pics along the way as the build progresses. 

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Works Performance shocks, CR or Simmons forks, and a serious diet is what it takes to be competitive.

I can't wait to see the finished product! You have a beast right there.

CR forks/21" front wheel so you have a selection of modern tires, Works Performance (or Ohlins if ya want to spend $$$) rear shocks to put the ass end up a bit higher and a major diet like ickfinger said... 

 

i did the above on a '79 or '80... did MX and desert on the bike and had a blast with a stock motor.  can't say i was super competitive, but i'd blame that more on the rider than the bike :D

I have already purchased a 81 cr450r which is the donor for my front end and a plastic tank and seat. It already has mullholland rear shocks but i think the front end is going to be soaring over the rear. My issue is the shocks are already 17 1/4 inches long and i havent been able to find a longer shock to get the rear up higher.

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Airtime , you might have to source another swingarm with different shock mounts , this way you could use a shorter shock mounted closer to the swingarm pivot point , greg

 

 

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Airtime , you might have to source another swingarm with different shock mounts , this way you could use a shorter shock mounted closer to the swingarm pivot point , greg

A reliable Maico

I was thinking about  a different model I was hoping somebody had mated a different swingarm on one so i had a good starting point. I have contemplated moving the mounts on the stock arm and welding a gusset to make it stronger cause i worry about it folding if not. So far i noticed the kaw klx 250 from the early 80's run a dual shock set up with a aluminum arm. It looks like a very promising possibility but you never know till its in your hands and next to the bike. I have a feeling it will be alot of trial and error. I guess that is alot of the fun though. 

Its not about suspension height, its about balance and setup

It is about height when the forks have double the travel of the stockers so it sits like a chopper right now. I need to level the bike out some. It will never turn like this.

I have a KDX 400 swing arm I might part with. Kinda like the KLX.

How much did you want for the kdx arm?

A reliable Maico

Beautiful build but the "Maico Breako" was mostly bs. The two I had and my Buls were 100% reliable and I flogged them in HS and Enduro for many years. Proper setup was the key.

Airtime,hi as i recall the 79 XR has loose balls in the steering head, ive been told you can knock out those and  use the stock cup n cone,but i speak under correction they are 27/54mm and believe the easiest front end to fit would be from a older cr as youve selected. I have had success fitting a 2ooo' RM front to a XR 500RB using the RM yolks and a kit from AllBalls cup and cone conversion...nice forks 49mm and great action.

A nother project,I kitted a XR500 RE(84) with USD kayabas,donour forks from a Yamaha YZ ,and I used the RM rear wheel and disk brake also ,converting from the 17' wheel to a 19" with disk..very simple job,only requiring a mod to the rear brake lever to opperate the master cylinder.The yolk bearings came cheaply from China.

Admittedly this doesnt help you much,as all these were monoshockers,and there were no issues of chopper style front ends.

As was stated your rake is excessive and  bike wont perform being more excessive once waited and race sag set.

I have seen DR 500 swing arms used for the twinshocker, and best try find out more about mugen frames and accessories.

I  believe it would be pretty much work getting weight shed from those old twin wall tube frames and damn hard to get the suspension working effectively withthose MX forks...maybe use bar raisers and push the fork tube as far as you can up in the yolks,till they touch the bars

Tell me while were talking CR 450..Im currently building an  IT 200,KDX 175 and CR250 both 81' models....what you do with the CR450 motor.....if its dead I am looking for a kikker shaft and lever..its same as my 250s....so please consider me if its going a begging.

I also have a 79 XR that i will refurb soon also another which strangely has a square tube swingarm...any way I have oodles of stock spares for XR so if anyone needs help,email me at motomikelevy@gmail.com or cindy@iway .na..Im in Namibia......Africa

Im gunna try upload pics of the front end conversions,but if theres no success ,yous can mail me for more info.

Nope not working..go look at our facebook page and its there with the other restos  'https://www.facebook.com/joesbikeclinic

Beautiful build but the "Maico Breako" was mostly bs. The two I had and my Buls were 100% reliable and I flogged them in HS and Enduro for many years. Proper setup was the key.

Yeah , i raced a AW250 in the 70's , ( it was just 1 race actually ) the bike was owned by a friend of mine . The " Maico Breako " was a popular saying back then .

I never owned one myself , but I will say .. The handling of the Maico I raced was exceptional .

Hey Airtime 391,

I as well race a local vintage circuit and wanted to ride something different.

I bought a ugly xr250, slapped on 77cr125 front forks and 21" wheel, mounted a xr200 tank and built a basic pipe. Had a 500 motor with bent valves and worn timing chain given to me. New rings, 2 valves and timing chain later, I now have a bike I will race Sunday for under $300!

photos progress before and after.

This winter I plan on going with the klx swing arm and maybe a yz front end. Along with an extended seat and refine everything and polishing a few things.

I also installed spacers in the forks about an inch long. It actually handles surprisingly well.

I'm curious if anyone has had experience with installing an xr250 flywheel (lighter)?

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Brother i love the bike. I am turning my flywheel down on a lathe to lighten it. I think i may have come across a profab aluminum swingarm so im keeping my fingers crossed there. I have alot of my parts ready to go i might do a mock up of things this weekend if so i will post pics. I am diligently seeking out what i need and trying to get everything together before i do the tear down because i am riding it stock at the moment with some of my other vintage buddies. They wont know what hit them once i roll it back out after the conversion.

Thank you, I've literally thrown it together in 3 weeks. A profab swing arm would be a fantastic find! What class rules are you having to follow?

We have an open 1975-1985 no disc class and next year a 4stroke with 9" of suspension class.

Obviously a C&J frame would be the class act, but I'm doing my best to keep it fun, cheap and hopefully competitive.

I've read about people removing the counter balancer to reduce weight but I think reliability would suffer.

Here are a few inspirational pictures I like.

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Dual shocks with the res's on the side look sick. I want an even older bike so I can do that. Haha. :)

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