1983 500CR Race Bike Project

I had the four hardened washers welded to the frame. This coming week, I should be able to start working with the details of the motor and prep the frame for its final color.

Enjoying your progress. Some pics would be awesome!

Okay, I'll start taking some tomorrow.

Here's some pics of the top end work. Cleaned the head with the compression release and the cylinder. There are two pics of the washers welded to the frame. I went with regular US sized thick hardened steel washers as the metric washers had too much play in them. I have to clean up the welds and finish the primer coat on the frame yet. I tried a lighter silver colored paint for the frame and it was just to bright. Going with a medium silver paint for the frame.

Lookin' good. What is the need for/idea behind the frame washers?

My experience with the 500 motor was that it had so much power it put added stress at the frame holes where the swingarm bolt went through in a jerking motion and oblonged the regular round holes on both sides. The frame section at that location is a single width piece of steel and needed to be beefed up. It's welded with hardened steel washers on both sides to provide support so in theory the swingarm remains in line and the rear wheel tracks straight. The 500 has enough power that it oblongs the hole in the frame that even if you beef it up so you keep an eye on it. Welding washers at this location was common practice/fix in those days. My 83 Maico has the same treatment at this location. Regular maintenance on the swingarm bearing assembly is key. The factory went with a larger size swingarm bolt in later years and I think that helped to resolve the problem.



The 83 and 84 use the two bolts on the right, newer models use the wider one on the left. I also have one of the original bolts somewhere in my garage that shows where it was worn down (narrowed, allows for more movement causing more wear and tear) at the frame junction.

I'm trying the compression release as this size motor can be a bear to start when your in the middle or end of a two hour hare scramble, fifteen miles from the start, and your a tired older rider. The compression release works well for the 490 Maico so it should work on this Husqvarna. Should be easier to start at the beginning of the race as we (Florida Trail Riders - Hare Scramble Series) use a Lemans type start where you run to your bike, start it up and take off. Not everyone's bike starts right away and this cuts down on the number of bikes at that first turn or when you have a line of bikes and only a single track trail 40" wide into the tight woods sections with no alternate lines available.

Very nice explanation and pic of the bolts. This is definitely a place we want correct and solid, and the frames are pretty thin there. It also seems to help minimize vibration to have everything snug here. I've learned to set them up so the engine is a little snug in between the frame rails before the bolt is tight, and you can really feel the difference when you torque the nut... it spins down solidly and just STOPS! I shimmed my 430 recently to get it just right and I swear the whole bike feels more solid.

Sorry, had'nt been on the site for a while. Good looking machine. Overall condition and price?
Steve

It does not just happen on the 500. I have a 1978 WR frame, 1982 250WR frame, and a 1983 250CR frame that all have the same elongation. It happens when the swingarm needle bearings seize(rust) to the sleeve the bearings run on and the sleeves then seize on the pivot bolt. The worst elongation is on the drive side but the 1978 WR frame has about equal elongation on both sides. The 1978 OR frame I have seemed to have had the pivot holes in the frame opened up. This scenario seems to occur over years of neglect or lack of pivot maintenance. Also to support this I got a 1983 500CR frame a couple years ago off eBay from Nevada. I got it cheap because of a break in the subframe. The swingarm pivots were not elongated whatsoever and the subframe break was an easy repair with my mig welder

Well, what ever it is, the trick is to be aware of the problem and keep up with the maintenance program.

Keep it coming Tommy, for those following the thread and enjoy working on these old bikes like myself, the swing arm pivot shaft becoming joined to the pivot bearings and the needle bearings is all too common. Cant hardly beat the shaft free after penetrating oil and the use of a sledge hammer. Like Jim mentioned, the wear and elongated holes is a result of motion forced upon the joint from motor pull, vibration, as well as the pivot bearings. Motion from the pivot bearing is increased when your swingarm bearings go south or freeze up from poor maintenance or no maintenance. When these forces continue to cause motion, wear occurs, and with the presence of dirt and continued operation the wear washer becomes toast. With wear and now worn faces, you also lose the clamping bolt torque. A loose joint further accelerates the wear. So like you said Tommy, some form of maintenance is key.

On another note: welding on frames can be detrimental if not performed by a professional welder. I'm not sure but I would suspect the frames are chrome-moly steel, possibly chrome-nickel-moly. Anytime welding is performed I would recommend preheating the immediate area to around 300-500 degrees F prior to welding. Proceed with your welding and when finished immediately heat the welded area again (post-heating) to around 700-800 degrees F. The welding industry sells temp markers/crayons to wipe the area to give you a temperature indication. Any effort towards these temperatures is much better than no effort. If the frames are not alloy, these pre-heat and post-heat temperatures would have no negative impact, so nothing lost other than effort.

Generally these frames are incredibly strong and flexible and last forever. On 500s and the 4Ts the right (sprocket side) flange is a weak point as it takes tremendous strain and vibration transfer, and i have broken them there landing WOT after big jumps (cracked from swing-arm bolt hole right down to hole for brake and then across to edge of flange) which makes the bike handle erratically like the back wheel is flat, and went down badly as a result.
Washers are ok, but generally i have a CrMo plate profile cut from 2,5mm sheeting and welded in professionally. Havent broken one of those yet.
Left side is a bitch with weld-ins as your kickstarter knuckle graunches on the swingarm nut (I run custom made 14mm swingarm bolts and nuts on the 500 2Ts). I prefer to leave the left side original if possible and have had no failures there as yet.

The frames are CrMo and i have welded them successfully with a normal DC arc-welder and special rods.

The cut-outs below the washer weld job pictured above is a stress concentrator and it will break there with severe use. Just considering your riding safety.

Thanks for the info on the swingarm. I'm satisfied with the work done by a local professional on the frame work. The motor is back and I gave the lower end it a coat of semi gloss black paint and will put it into the frame this weekend. I will start reassembling the motor with the new parts and decent used parts on hand and see how far I can go. I'll take some pics of the progress.

Just a few progress shots.

I have two sets of wheels. Will keep one stock and will polish up the second set. I set the decompression lever in and find that it's probably going to be to short with not enough of the knob to grab. Will fabricate a spacer to resolve that issue. I am sending my rear shocks out this week for a rebuild. Painting the shocks silver with black springs. Getting away from the standard colors and making this one a little different looking. Don't get me wrong, I like the stock colors but wanted something different.

you know you dont need to pull the decomp back out aye ? it pops out as soon as the engine fires . eg the engine firing blows the valve shut .
push in , kick , ride , stop . repeat

anybody tried the auto decomp system used on the r&d heads for the wr360 here in oz, there is a briggs and stratton easy start valve wound into the threaded decomp port in the head witha a vacuum tube running to the inlet manifold, vacuum from the manifold closes the valve when firing.

http://www.cafehusky.com/threads/auto-decompression-conversion-for-2-stroke-husky-easy.15000/