I needed an engine and wheels to use in my frame build project for school. I lives next door to XS650 specialist Jerry van der Heiden of Heiden tuning so I gave him a visit. He had an imported XS for sale without Dutch licence plates.
I did nothing to the yamaha xs650 engine or other parts, just fitted them in the new frame for display. After finishing the project it disappeared some were in the back of a barn and was forgotten. I found it again and dicide to finish it.
The engine was taken appart check and turned out only the gears were ok… New rods were fitted and the crankshaft was balanced and welded so it would stay this way. 710cc pistons are fitted in combination with a offroad sidecar camshaft and racing springs. For more oil circulation a large oilpump is fitted. Further some Heiden tuning special goodies like an external cartgidge oil filter and cooler.
The carburettors were replaced with Mikuni 34VM’s with K&N filters and the inlet rubbers are extended with aluminium manifolds for better low performance. On the outlet side two peashooters were mounted. (very nice sound!) A Boyer-Brandsen ignition set makes it a perfect starter. Heiden tuning had a nice deal on brake disks so two disks were bought in.
A mate had a very large Honda CR750 racing-like polyester tank he didn’t used anymore. It fitted the XS650 perfect.
I bought a polyester caferacer seat witch I modified a bit and let it upholster. Like all british caferacers have a red seam on the seat I chose a gray one, matching the color of the tank.
To hide the battery I made a polyester oil tank (based on a Honda CR750). This also hide the new R/R. A rearset was made from scratch using passenger foot steps of a modern supersport. The gearshifter was shortened and simply turned backwards. The rearbrake was also made from scratch using a brake rod from an old BMW. The drum lever was turned upwards. The rearset and all modified parts were rechromed.
Little meters replaced the large speedo and rev counter. To honor the US origin of the XS I placed a MPH speedo (iso KMH) Got used to it very quick. The bike did ride ok. Absolute no comfort and the roadsigns blurred above 60 but fun when not on the highway.
After a few years of caferacing the problems with the polyester fueltank appeared. I tried a aluminum tank but I had enough of the stretched riding. I went surfing on the net and ended up on the site of Mule motorcycles. I liked the simpliness of these bikes and also liked the up right riding position but still in a sporty way. I did had some offroad experiance but was fed up with being chased by law enforcement for riding motocross bikes on public roads and forrest. (In Holland all forrest is national park…) This seems a nice kind of bike to ride on public forrest (sand/gravel) roads without the risk of becomming a ‘dangerous criminal’.
One thing was a must, the Yamaha YZ400 gas tank. I found one on Ebay US for a bargan. The shipment was double the purchase price. Two petcocks replaced the single outlet so both carburettors have their own fuel supply.
The engine was still perfect. Only replaced the piston rings because they were out for check anyway. I did replace the inlet manifolds for one piece angled flattrack manifolds. Due to these manifolds the carburettors moved outwards to place a bigger (original) battery. (the caferacer was kickstart only and had a very small battery) Now I could mount the starter motor again.
The rear frame was changed to fit the flat track seat and rearlight. (It’s the same as on the caferacer but up side down 😉 Like the Mule bikes I mounted a HD Sportster headlight cover. The rev counter was removed and caped off. The speedo was replaced by a cheap bicycle computer. The display fitted perfect into the headlight cover for a clean look.
A flattrack handlebar is fitted and a Yamaha R1 light switch housing. In this part has a kill switch, horn (used for starter motor now) and light on- off- and high beam. I discarded the turnsignals to keep the left side of the handle bar clean.
Longer and softer rear suspention and modified front springs and bushings makes is a smooth ride on and offroad.
The exhaust is replaced by the performance 2 in 1 system from Heide tuning. A Supertrapp ‘silencing’. The paint is done with spray cans. Also the clearcoat. (thanks to the availability of 2K clearcoat in spraycans) Some stickers makes it a bit modern looking.
This all is 160kg (360lbs). Very light knowing a large battery and starter motor is included! The bike is very much fun to ride. On short and twisty roads this 35 years old bit will keep up with the supersports. Sliding into a corner is no problem and thanks to ‘missing’ 100HP to the fast bikes I don’t have to be afraid of powerwheelies or losing grip by twisting the throttle to eager.
The highway is a no-go. But with plenty of twisty roads (tarmac and sand/gravel) around I don’t see this as a disadvantage. Got a Africa twin for offroading further from home.
Think I will keep it in the shead for a while.
Michel van Rossen
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