1973 SR 643B Eagle River Build


No new pictures but we have decided to go with a 78mm bore on this project. That will put the displacement of the sled at 669cc. We will also hopefully be running some 46mm taper bored round slide carbs. The heads and crank are being reworked and the pipes will remain as they were. Nothing can be said about power at this point but the sled will hopefully be in the 125-130 HP range on modern day dynos. When I recieve new pictures, I will keep you updated.
 
Glad to see Ed's sled with be back out racing.... although it will have to turn left now! The WC is a whole different breed of racing. Let me know if I can be of any help

Monty
 
The chassis was taken out and cleaned top to bottom before some welding and reinforcing takes place. Here are some pictures of the chassis all cleaned...probably took a pound of dirt off the thing today. The entire chassis shown in the pictures weighs in at a whopping 51 pounds and the serial of the 292 chassis is number 192. Once the chassis is welded up, it will be polished up and progress will continue. The steering mechanism will be shifted over to the right side of the chassis about 3 inches to provide extra steering leverage. This will also allow for us to make a new motor plate so the engine can be dropped ~2 inches to lower the C of G significantly.







 
looks like you have alot of work ahead of you, but you still have lots of time! enjoy the build. looking forward to seeing how it comes out.
 
Here is a short update of what is going on with this build. The cylinders and pistons are back and the engine will be a 78mm bore putting the displacement at 669cc. The crankshaft still needs to be reworked. Here is the plan for the drive system of the sled. We will be making this custom belt drive system which lowers the jackshaft (aka secondary) ~5" lower. The entire system not including the jackshaft and driveaxle (both made from aluminum dropping substantial weight) weighs in just under 10 pounds. That is bolts, bearings, screws everything. This will drop ~10 pounds off the stock chain drive system and as I mentioned the jackshaft will be lowered which brings the ~13# secondary 5" lower. The drive axle will be moved back ~5.5" from the original location so a tunnel extension will be required. The engine plate will also be lowered ~1.5-2" to bring the heavy power block that much lower. This should eliminate much of the ski lift that might be a problem when going through the turns. We will be custom making some skis running our carbide. Here are some pictures of what the drive system will look like when it is completed.





 
Here is a slight update of the build. So far we are still waiting on a crank part as well as the gears and shafts for the belt drive. Outside of these missing elements, the sled is ready to be built. Below are pictures of the frame with some stiffeners welded into place, the rotor that will be mounted on the driveaxle (very light), and the lowered engine mount plate that is extremely strong to prevent possible breaking (dropping the engine 1.5 inches). More pictures will be included the further we get but the belt drive parts are all completed outside of the gears and shafts.

-Matt

http://imageshack.us/photo/my-images/20/rotorw.jpg/






 
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were are you planing on mounting the gas tank? There is so much room under the tunnel in the front of the SR'S i would put the gas tank there so the center of gravity is lower. that my two cents. i would be intrested in the stock sr643 skis if you want to sell them?

Thanks Joey
 
Here is another SR 643 we just picked up. We intend on restoring this one to stock condition and cleaning it up significantly. Our eagle river racer has been slightly put on hold with a couple of exceptions. We are relocating the steering and having the final parts of the motor completed.







 
Well guys, here are some updates on this build finally. We are finally figuring out all of the big changes to the sled and it is coming along very slowly but very nicely. We finally got all of the engine parts back so the engine is now assembled and ready for install. The final design for our northstar skis has also been solved in order to have a functional CAM system with a fox float shock. The seat material is still on the way but the ply wood on the chassis is the base of it. So much weight has been taken out of this sled and lowered. We are truly anxious to see how light we can get it. The steering system was also re-designed as you can see due to the dropping of the engine plate. The lube tank was then mounted under the tunnel as shown in the picture. I am sure there are a lot of things I am forgetting so if you see something funny on the sled, just ask. Here are some update pictures as we are still waiting to get the gears and driveaxles back.









 
Nice idea with the lube tank. I have not seen that done before. Im trying to talk your dad into racing with us in rock rapids iowa on 12/17 - 19. First land track of the season. 1/3 mile high banking......

Monty
 
Sweet SR....I had the opportunity to see a few at the A1 Swap and Show near Flint, MI over the weekend....pretty cool!
 

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