Enduro conversions Yamaha TT-R 600

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Enduro conversions Yamaha TT-R 600
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Enduro conversions Yamaha TT-R 600

Enduro conversions Yamaha TT-R 600

Enduro conversions Yamaha TT-R 600

Enduro conversions Yamaha TT-R 600

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Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Pure enduro culture: builder Johann Forg with Yamaha TT-R / XS (left) and her sister TT-R / GR (right).

Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Yamaha TT-R / XS
Technical specifications
Air-cooled two-cylinder four-stroke in-line engine, 653 cm³, 51 HP at 6940 / min, 54 Nm at 6000 / min, bore / stroke 75/74 mm, compression 8.4: 1, two 38 mm constant pressure carburetors, an overhead, chain-driven camshaft, two valves per cylinder, no balance shaft, five-speed gearbox. Single-loop frame made of tubular steel, 46 mm telescopic fork, aluminum swing arm, central spring strut, spring travel f / h 280/280 mm, tires f / h 90/90 R 21/130/80 R 18, disc brakes f / h 267/220 mm, steering head angle 63 Degree, caster 114 mm, weight full-
fueled 158 kg, tank capacity 8.8 l, seat height 940 mm.

Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Johann has taken the XT 500 concept a step further: simply constructed two-cylinder, light chassis with a lot of suspension travel, decent brakes and 12-volt electrical system, the center of which is now in the old TT oil tank (below). In addition, details such as lamp holders made from bicycle seat posts. Carburetor close to the frame, screws in rubber damping.

Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Yamaha TT-R / GR
Technical specifications
Air-cooled two-cylinder four-stroke in-line engine, 647 cm³, 50 HP at 7200 / min, 51 Nm at 6000 / min, bore / stroke 77/70 mm, compression 8.7: 1, two 36 mm constant pressure carburettors, two chain-driven camshafts at the top , Bucket tappets, two valves / cyl., Two-mass flywheel, 180 degree crank pin offset, electric starter, five-speed gearbox. Double loop frame made of tubular steel, 46 mm telescopic fork, aluminum swing arm, central spring strut, suspension travel f / h 280/280 mm, tires f / h 90/90 R 21/130/80 R 18, geometry like TT-R, weight with a full tank 158 kg, Tankinh. 9 l, seat 940 mm. Construction time six months.

Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Enduro conversions Yamaha TT-R 600
Markus Biebricher

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Not a gram of fat: robust Yamaha TT-R with Suzuki GR 650 engine. The division of the frame loops is color-coded, the tubes are inserted into each other and are reinforced by the engine guard. The fuel tap is magnetically fixed, the Li-Ion battery compensates for the weight of the exhaust. The engine sits tightly in the frame.

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Enduro conversions Yamaha TT-R 600

Enduro conversions Yamaha TT-R 600
Remove single cylinder, install in-line twin

The dream of every off-road fan: a light, slim enduro. Such devices are usually fired by jarring single cylinders. MOTORRAD reader Johann Forg wanted full torque, smoothness and sound instead. He swapped the single in the Yamaha TT-R 600 for a 650 in-line twin. And that twice.

Markus Biebricher, Johann Forg

03/30/2017

“Off-road driving has always been my great passion”, says Johann Forg with flashing eyes. The owner of an industrial maintenance company in Augsburg has been a MOTORRAD subscriber for over 40 years and has been riding Enduro since 1975. At the age of 60 he has become calmer when it comes to driving and has even ordered brochures for e-bikes. With a Yamaha drive, of course, because Johann’s heart has belonged to this brand from the start. His path starts on the two-stroke enduro DT 250. This is followed by the four-stroke steam hammers XT 500, XT 550 and later the Belgarda-TT up to the TT-R. Trial machines and EML motocross combinations with an XS 650 engine complete Johann’s motorcycle career.

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Remove single cylinder, install in-line twin

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Now if this two-cylinder would fit into the TT-R?

Leisure time means driving and screwing for the likeable Augsburger. There is always something to improve on both motorcycles and riding skills. And so they grow together, Johann and his machines. At some point the garage will burst at the seams. But how on earth can you sell your treasures after you’ve seen so much with them? One evening in autumn 2015, Johann is once again standing in front of his off-road vehicle fleet. He pensively looks at the beautifully restored EML team with the wonderful XS 650 twin, which has been drilled to 1000 cubic meters. Next to it is his son’s TT-R. Suddenly Johann got the idea: what if this two-cylinder with strong character would fit into the TT-R? The trained industrial mechanic feverishly misses the twin. It will fit, Johann is sure of that.

Shortly afterwards, he finds an original XS drive online, which he restores. Then he builds a motor stand that can be adjusted in height and incline. He dismantles the TT-R and rebuilds it around the engine. The frame has to be reinforced at the front, which cannot be done without welding. To Johann’s delight, his son carries out the necessary welding work professionally and professionally.

What a sound!

The chain alignment is balanced with an 8 mm offset sprocket, and even the 280 mm rear travel can be maintained with a little effort. The transition from the two carburettors to the original air filter is also complicated, because the TT-R frame is cut extremely tight.

Because the original tank and the original seat no longer fit after the modifications, Johann decides to adapt the look of his dream enduro to that of the legendary XT 500. So an original XT tank is needed, a seat is made just as meticulously as all the necessary brackets. Johann goes to great lengths to ensure that all parts are easy to dismantle for maintenance purposes.

The friendly employees from the XS shop help with the electrics, pull in a new wiring harness and convert the ignition to contactless. Then the motorcycle is dismantled again, all parts powder-coated, painted or foiled. After assembly, Johann is moved in front of the enduro of his dreams.

Then the big moment: after three or four kicks on the kickstarter, the twin starts running. What a sound! Johann drives his secret routes and is thrilled. The twin pushes out powerfully from below, which is also due to the shorter translation. The 158 kilo motorcycle can be controlled playfully, and the rides are pure enjoyment. Again and again.

Zweizalinder of the GR 650 in the XT 550

At some point the season is over. Johann reads in old MOTORRAD magazines and stumbles over the test of the Suzuki GR 650 from 1983. At that time Johann drove an XT 550 and was annoyed about the rapid death of the single in the field. The two-cylinder Suzuki GR has a variable flywheel. At the time, Johann had the idea of ​​installing this technology in the single cylinder of the XT 550 in order to make it easier to drive in the lower rev range. An idea that he didn’t realize.

But now: Because his son has a second TT-R standing around, he decides to transfer the GR-Twin to the Yamaha frame and build a second dream enduro. While the legendary XS 650 engine as a classic parallel twin delivers a lot of torque from below, but also rustic vibrations, Suzuki made its GR two-cylinder with 180-degree crank pin offset to counter-run in order to reduce the inertia forces. But since there was less steam in the lower speed range, the Suzuki engineers reached into their bag of tricks: a split flywheel attached to the left crankshaft stub. Both indexing disks are active below 2500 rpm. The additional flywheel ensures great running smoothness and plenty of bangs from the cellar. Above this speed, a centrifugal clutch automatically disengages the additional pulley, and only the main pulley remains. Now the GR can spin up freely. 

Climb down trial-like on the torque wave, above it fast revving. Fantastic characteristics for an enduro, right? So Johann bought a used GR and started heart surgery number two. The Suzuki engine requires more interventions in the frame construction of the TT-R than was the case with the XS transplant. Johann is now building up the frame with two loops at the front and making the lower part of the frame removable. In this way, the precisely fitted heart can be expanded quickly. 

The tinkerer will also find clever detailed solutions for this conversion: lithium-ion battery under the rear frame, fuel tap fixed by magnet, electrics in the old TT-R oil tank (on both bikes) and much more. The look of the dream enduro number two becomes independent, leaves more design freedom. A DT 400 aluminum tank gives the machine that special touch. It starts soon. Johann burns the brochures for e-bikes in the workshop oven.

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