Scorpion, 1969, Mark 3 with a Hirth 634cc. The SR number of the chassis is 478494. This J-400 frame and 634cc Hirth was produced only in 1969. It has be stored inside and is quite original. The cylinders still have compression over 95 PSI. The carburetor is clean and functional. The driving clutch works very well and the driven needs a little lube. The low voltage wiring is brittle, broken, and needs to be replaced along with the key switch. The 18" track is original. The hood has a special air scoop for the cooling and needs attention. The red vinyl seat is in very good to excellent condition. The body has some fine rust. The boogies and springs are functional. There is the original Owners Manual for the sled and the engine, complete with the "Factory Technical Bulletin" for the points and timing. Photos are available upon request. The phone contact is 715-676-2446 - evenings. 715-387-9578 work and leave a message
Thanks for your input. Attached is the photo of the hood design with that special 'scoop' which I have not seen another one of. It does have an 18"track. Any other identification would be appreciated. Thanks...
ddub: See the attached additional photos. I did verify the registration reads 1969. I checked the hood out ....there never was a opening for a grille for air intake like most models. Usually the grille was on the front lower, just above the bumper line, and there was no fill in. Any other input is appreciated. There was only 8" of snow in Northcental Wisc. today, but the machines were out.
Attached are a couple more photos....details of the hood. This one never had a hinge system. Held in place with the bottom edge of the hood sitting in a kerf and the six bumper bolts holding it in place. The photo of the exterior of the hood looks terrible, but it is in fair to good condition....no holes as it may look like. All three of you guy's are very observant....Sting 3: you are correct! The stripe near the taillight is the original. As you all noted, the hood stripe does not match. I 'now' recall that in the early 70's, I touched up the black paint and put on the stripe that was available at that time. Back to the hood scoop. We acquired the machine in 69 as it is. ddub: It does a great job of keeping the engine cool. It is very functional. The track has always been stored 'off the ground'. It's in good enough shape to make a few laps @ homecoming event or two. Since 69 I have put 95% of the miles on it, with leisure (25 mile) round trips to the local lake with a few friends. Really enjoyed it in the 70's. Admin: Question...The Scorpion Specification sheets say that 69 and 70 were the only years that the 634 was installed in this sled. (This same engine was used in small airplanes). What is the major difference between a Mark 2 and 3? Receiving 5" of snow this evening!
Admin: Question...The Scorpion Specification sheets say that 69 and 70 were the only years that the 634 was installed in this sled. (This same engine was used in small airplanes). What is the major difference between a Mark 2 and 3? Receiving 5" of snow this evening!
Off the top of my head, I think the major difference is the Mark III has the 18" wide track and of course the tunnel is wider because of it. Also, I think the Mark III has the storage compartment under the seat whereas the Mark II is a 15" track with no storage compartment.
One other note, the 69 Mark III I have has the seat hinge on the side of the seat whereas the 70' Mark III has the Seat hinge on the front of the seat!
The 69' models have the ignition key mounted in the hole on the right side of the hood whereas the 70' has the key mounted in a metal plate that is welded to the handlebar support. This difference is probably because the 70' has the hinged hood, so they did not have to make the ignition switch wires longer to accommodate a moving hood because they mounted the ignition switch on the handlebar support that does not move with the hood.
Feel free to correct me if I am wrong on this Team!
Thanks for posting the extra photos. I would think getting extra cool air to pass over that AIR COOLED engine would be a good idea!
That is a Free-Air cooled engine, right? Or is it fan cooled as well?
Admin: Everything you stated .....18" track, side hinged seat, key on the right side of the hood, and yes...its air cooled. You have ID'ed it as a 69. Thank you for the clarifications. You have a great site here!
I was just sent the site for our '2011 Big St. Germain Run' at
Krainz, Thank you for taking the time to take the pics and post them.
Interesting scoop. I would guess that cooling would be much better with the holes. I do find it hard to believe that a 634 (even the 440) could stay cool without some sort of fresh air that a bubble hood did not provide.
Really that bubble was probably best suited for the Sachs singles which were most of the production until 70. Then in 70 they at least had the hinge/grill to let in some air and the twin grills in the Stinger models.
Admin: Fantastic photo's of the 570m Hirth, the Drone, double Trouble, and the 700 Mark 2. Very impressed with what was done to create horsepower and speed. All we need is someone like ddub to add a 634 twin to the list. (Need to put a smiley face on that one.) I double checked and the 634 is just air cooled...no fan. To a great group of enthusiasts....