The BMW should satisfy my desire to have a bike in need of some maintenance on a level I can perform by myself, however a 21-year-old BMW requires surprisingly little maintenance. So, this spring I started to look for a suitable project bike. I was interested in in a bike not in need of a full restoration – am too impatient for that. Something that is drivable but requires a gentle hand to be kept going and that is easy to maintain would be a suitable object.
Then this 40-year-old appeared. A little too much for my budget, but SR 500s that have not been converted into café racers or bratbikes are not easy to find, so I decided to go for it. On Monday May 25th, I invited my son Espen to join me on a trip to Halden to pick up the SR. We rode inland roads and had an incredibly nice ride. It was an exceptionally nice day – one of the warm days we had in May. Great conditions for picking up an unknown 40-year-old motorcycle.
The first impression was very good, much better than expected. No rust on the frame and no corrosion on the aluminium. A small dent in the tank and some small scratches on the tank and on rear and side covers. After a while we got it started. It’s been a long time since I have ridden a motorcycle with a kick-starter. I have not ridden one with a kick-starter only since I was 19 and rode a Suzuki GT 380. It all seemed a little scary. The GT 380 with a three-cylinder two-stroke engine was super easy to start. The SR 500 is not. And I was excited about how this would be. We stopped for petrol in Rakkestad, and guess what – the SR started on the first attempt!
Espen rode the Yamaha to Rakkestad and was impressed by how easy it was to ride and how well it handled. He was impressed by the power and response at lower speeds. He daily ride is a Kawasaki GPZ 500 which need much more rpm to perform. I ride the SR 500 from Rakkestad, and I am surprised by how easy it handles. It lacks the stability of the BMW R 100 RS, and that steering head bearings rattles and need some adjustment. The brakes are not up to modern standards, but I think this can get better by a proper brake overhaul. The sound from the short exhaust pot is too loud, and I will fit the long replacement exhaust muffler that came with bike.
The seating position is very comfortably, especially at highway speeds, I really feel at home. On the highway I am in the wind, at it feels good. I should be able to do some miles of highway at decent speeds. As we are almost home, there is an annoying squeaking sound I am not able to locate. I had noticed that the chain was very tight before we started from Halden, but I reckoned we would make it home without problems. In a way, it we didn’t. When we got home the chain was tight like a piano string, it helped to spin the rear wheel – so it seems like the chain is unevenly worn. The squeaking sound was not from the chain. A couple of days later I managed to locate the sound to the speedometer. Clearly there were some gears that were not engaged and explained why the speedometer needle had started to dance over the scale.
I had planned to use the bike during the summer. This summer became quite different from what the most of us had planned, and there were not many opportunities to take motorcycle rides for me. And the project stayed in the garage and it turned out that I stayed busy with the SR 500. Here are some of the things I have had the pleasure to attend to:
- Adjusted the chain and found that it had an uneven length
- Fastened the front sprocket
- Adjusted steering bearings
- Lubricated cables and replaced clutch cable
- Adjusted the rear brake
- Overhauled the master brake cylinder
- Overhauled the front brake calliper
- Installed new brake lines
- Overhauled the original carburettor
- Fixed the front fender
- Fixed the chain guard
- Adjusted the cam chain tension
- Adjusted the valves
- Opened the alternator, found a loose screw inside the rotor
- Replace screw on ignition pickup
- Lubricate all lubrication points
- Checked all screws and nuts and changed to the correct dimension and type where necessary
- Changed oil and oil filter and fitted new gaskets and replaced missing O-ring.
- Installed the large exhaust muffler
I have no intentions of making this a restoration, but there were some things I just had to do. The first purchase was easy; right on eBay and get a new speedometer. I was not happy with the carburettor and the air filter solution, although it worked it was not as it should be. The original carburettor came with the bike, so I bought a carburettor rebuild set and overhauled it. I also bought a used air filter box and after a wash it looked like new and the installation was simple. With two new throttle cables the original carburettor was in place.
Parts that were broken were on my list of components I wanted to fix. The front and rear fenders were ripe for replacement. On the front fender, the chrome was worn away by the clutch cable. The rear fender had functioned as a luggage rack and was dented and lacked chrome coating as well. I changed the clutch cable and routed it, so it isn’t in contact with the fender. The chain guard was twisted and had lots of dents. New front and rear fender and chain guard were ordered and installed. The paint on the tank and the side covers have some wear but this is a 40 years old bike, so I think the will stay as they are. The cover at the rear of the seat was broken and frayed at the edges. I replaced it with e new one and painted it in original colour and with KEDO seat fairing decal.
While the rear tire is relatively new, the front tire was well worn and 12 years old. New front tire that matches the rear tire was ordered and fitted together with a new tube. The rear brake was adjusted and works excellently. The front brake, on the other hand, was not as impressive and I ordered a set of brake lines from Springer brake and a rebuild set for both brake master pump and the calliper and overhauled both, including painting. Everything was reassembled with new brake lines and brake pads. I also disassembled the handlebar stem and painted the fork clamps. At the same time, I checked the steering bearings which were already upgraded with tapered bearings and with a little new lubrication and a basic adjustment were like new again.
The short exhaust muffler that was on the bike when we picked up the bike was stained and very ugly. I seem like both the chain guard and the muffler had had a spray of brake acid. As a small project after doing everything else on my list, I decided to try and get the muffler back to near original condition. I started with a 1500 wet sanding paper and managed to sand away all the stains and polish the pot back to the original gloss. Then I fixed the fasteners and the short muffler is ready for service if I should decide to have some more sound.
The last big thing of the project was to get the engine running. As I took of the generator flywheel and the timing plate, I hadn’t made any marks on the position of the timing plate. On reassembly I was not quite sure of the position and decided to use the factory marks. I wasn’t convinced that this was correct, and I wanted to check the timing. Then I discovered that det Haynes manual referred to a different set of timing marks than those on my flywheel generator. So here I have something to sort out.
Now it is parked along the R 1100 RS in the innermost part of the garage and will remain there until the spring. I will always find some minor things to attend to and make an excuse to take it out of hibernation. So far it has given me much joy – now I am looking forward to riding it as well?
May 2021
Spring came and the SR stood there in all its glory and ready for adventure. Now I used the original carburettor. The engine started easily and ran flawlessly. Strong at the bottom of the rev range and with proper stamina in the upper part of the rev range. I had some very nice trips, before things got really messy. I was going to Sarpsborg to pick up a part for the tank bag of the RS and thought it would be a nice trip for the SR. It all started fine, but at Raade the engine started to run a little rough, and suddenly it was completely without ignition, but as I entered the road shoulder it decided to work again, but very reluctantly. It continued like this, the engine would prefer not to go too low on the speed register, then it got worse. I managed to keep it going until I turned off the E6 at Årum, then it stopped.
It was trailered home, and when I picked down the top and cylinder I found a damaged piston, and the cylinder also had marks and aluminum residues from the piston. A new piston was ordered and I got the cylinder fixed, then everything was put together again and I put on the original carburettor. It had a small leak which I was able to locate to the gasket/diaphragm on the acceleration pump. I blocked the acceleration pump and everything was back in place. So a little test start, perfect. Everything worked as it should.
The season was over and the SR stood next to the RS again, waiting for the new spring.
May 2022
Then came spring. Nothing major has happened in the garage during the winter, but there have been some minor issues to fix. Now the SR is ready for a test ride. It runs great. I’m thinking a bit about why the engine was damaged. I think it might be because it had a hig compression piston. So is the new piston. To prevent the engine from running too hot I have adjusted the carburators nozzle needle up a couple of notches and fitted a slightly larger main nozzle. It works great, the engine starts easily and runs better than before. But I’m still a little skeptical. On a trip west on Ring 3, there is a sudden stop in a tunnel. Not ideal at all. It was a lot of sweat before I got out of that situation.
No ignition was the immediate diagnosis. I was going to visit my grandchildren, so I parked the SR and continued my travel by bus. On my way back I stopped at the SR again, thought I’d have to give it a try before renting a trailer to pick it up. The SR started on the first kick and I rode home without a single mistake from the 42-year-old. I experienced something similar once before, that time ignition coil was the problem. I parked the SR, I had enough other things to tend to right now.
So – after I had sold the RS I thought I tried to find what was wrong with the SR. I was going on a small errand and chose the SR for the trip. Had only gone three kilometers before the engine suddenly stopped. I parked the bike and took the tram home where I picked up the 750X and did the errands. On my way back I stopped at the SR, still zero ignition. I removed the seat and checked all contacts. Nothing wrong to see. But now it started on the first try. Back home, I managed to locate the problem to the 6-pin connector leading to the ignition box. I got all the contacts fixed and it turned out that three of them were so loose that they had no contact. I tightened the connectors, put everything back together and started the engine. Now I could pull the connectors without the engine misfiring or stopping. The problem is solved.
There are still some small things I can fix, but now the SR is in good condition. I will post it for sale on Finn.no. A few days later it was sold. I have enjoyed the SR and had some fantastic driving experiences. Now I hope someone else will enjoy it both on the road and in the garage.
Yamaha SR 500 1980: Bought May 2021, sold October 2022.
A couple of useful links for SR 500 owners:
YAMAHA SR 500 1980
SPECIFICATIONS
Engine: 1-cylinder four-stroke. Air cooled. 1 carburettor.
Compression: 9,0:1.
Starter: Kickstarter.
Bore x stroke: 87 x 84 mm.
Cylinder volume: 499 ccm.
Power: 27 hk at 6500 o/min.
Torque: 36,3 Nm at 5500 o/min.
Transmission: 5-speed. Chain.
Fuel capacity: 12 litres.
Frame: Steel.
Dyres: 3.50-19 front, 4.00-18 rear.
Brakes: One disc and callipper wit 1 piston front. Drum brake rear.
Weight (wet): 175 kg.
Top speed: ca. 160 km/t.