76 250 merc mph

[E-charger]

My old Tech school instructor Marlin Peterman form Evansville MN held a record Meany years ago with I believe back then it was an ISR event, could have been an NSSR event, the event was held on the lake in front of the Radisson Arrowood in Alexandria MN. He ran with a Yamaha 250 Enticer, in the stock class he ran 70 mph in 1000 feet on an ice track, the sled was completely stock with no engine mods and all stock clutches retuned for top speed and geared for the 1000 foot run and jetted for jet of the day. Some of Marlins tricks were playing with belt side pressure and clutch alignment then light weight riders and free rolling chassis. I would think that twister has more to go with the right kind of tinkering. The clutch tuning tricks that Marlin did came mostly right from Olav Aaen’s clutch tuning book. He set up what he called the (rocking chair) what he meant was he would set the suspension up to rock back and hold the skis just off the ice. One other trick is to run just as close to the radar gun when you go by as possible, another trick is to run a zigzag path down the chute, this allows for a longer run, when you do this make sure you end up as close to the radar gun as possible when you go by.


Maybe this is common knowledge but some other tricks are scrubbing the sides of the belt with acetone and a (clean) rag then using a propane torch to burn the frizzes from the sides of the belt, then use 180 grit sand paper to dress the sheave faces of both the drive and driven clutches then when you prep the belt also clean the sheave faces with acetone so that the clutches and belt are clean at each run. Another thing to do is to mark the clutches with a crayon by drawing a line at the top of the drive and at the bottom of the secondary clutch by doing this you can get a feel for what type of ending ratio you are running at the end of the run this will help you set up your gearing. Gear to run the clutches at a one to one ratio the one to one ratio will be the most efficient ratio you can run when your belt side pressure is set to the lightest setting it can be with out slipping, the low side pressure gives the least amount of friction when pulling the belt out of the sheave faces as the clutches turn. Like propping a boat a good accurate tachometer is essential pay attention to the RPM all through the run and hold the engine on the power, in clutching for a radar run don’t worry about back shifting instead watch to see that the RPMs don’t sag back on the run.

[Vintagesleds.com]

[BWCAT]

There are many tricks that have been used over the years. My father took my little Cat Z and put in all double sealed bearing and injected them with Teflon. We gained 3 mph the next weekend. Depends on how much time you want to spend.

[skeg777]

My old Tech school instructor Marlin Peterman form Evansville MN held a record Meany years ago with I believe back then it was an ISR event, could have been an NSSR event, the event was held on the lake in front of the Radisson Arrowood in Alexandria MN. He ran with a Yamaha 250 Enticer, in the stock class he ran 70 mph in 1000 feet on an ice track, the sled was completely stock with no engine mods and all stock clutches retuned for top speed and geared for the 1000 foot run and jetted for jet of the day. Some of Marlins tricks were playing with belt side pressure and clutch alignment then light weight riders and free rolling chassis. I would think that twister has more to go with the right kind of tinkering. The clutch tuning tricks that Marlin did came mostly right from Olav Aaen’s clutch tuning book. He set up what he called the (rocking chair) what he meant was he would set the suspension up to rock back and hold the skis just off the ice. One other trick is to run just as close to the radar gun when you go by as possible, another trick is to run a zigzag path down the chute, this allows for a longer run, when you do this make sure you end up as close to the radar gun as possible when you go by.


Maybe this is common knowledge but some other tricks are scrubbing the sides of the belt with acetone and a (clean) rag then using a propane torch to burn the frizzes from the sides of the belt, then use 180 grit sand paper to dress the sheave faces of both the drive and driven clutches then when you prep the belt also clean the sheave faces with acetone so that the clutches and belt are clean at each run. Another thing to do is to mark the clutches with a crayon by drawing a line at the top of the drive and at the bottom of the secondary clutch by doing this you can get a feel for what type of ending ratio you are running at the end of the run this will help you set up your gearing. Gear to run the clutches at a one to one ratio the one to one ratio will be the most efficient ratio you can run when your belt side pressure is set to the lightest setting it can be with out slipping, the low side pressure gives the least amount of friction when pulling the belt out of the sheave faces as the clutches turn. Like propping a boat a good accurate tachometer is essential pay attention to the RPM all through the run and hold the engine on the power, in clutching for a radar run don’t worry about back shifting instead watch to see that the RPMs don’t sag back on the run.

nice to here marlins name  we lived neighbors to them, he lives by lake jenny yet.  he always had fast stuff including his dads 57 chev  fastest stock car ive seen   283

[back in the day racing]

Didn't do so good in Forest Lake. Could only get 66mph. Track was soft and 45 degrees out.But went up to Crane Lake yesterday and ran 68.52 at 40 degrees . The nos cat spring helped  instead of the LLP green. When I took it out it was about 1/2 shorter then when I put it in. Don't think I am getting 1to1 on the clutches with running a 1 1/2 belt detection. Any thing less and can get it to not creap and idol. But I still want to put bigger drivers on.But some one on here said Swiss cheese. I was thinking about 6.5 drivers with .700 studs and putting 1inch tunnel protectors on. Any opinions on this? Also going to a 16tooth top sprocket and a comet primary with the cat reverse secondary.

[back in the day racing]

My little twister

[back in the day racing]

Check out the autograph

[E-charger]

Nice little Merc, hummmmmm 66-68, show me a winner and I will show you a cheater, time to roll up the sleeves and wake that thing up……. Maybe clip some off the intake skirts of the pistons maybe widdle a little on the piston crown chamfer as per Gordon Jennings (Two stroke tuners hand book), maybe some adjustments to the compression, thinner head gasket, thicker cylinder base gaskets, maybe cut a little off the pipe flanges could do blatant port changes and pipe changes kind of a hard time finding replacement parts, piston changes make it easier to go back to stock and can go pretty far. Get that chassis rolling freely, slide lube to the rails, idler wheels where there is heavy ware to the hyfax, work with track tension get her to roll get a 95 LBS driver….. I would think that thing should run out somewhere around the 75+ MPH mark on good ice in a thousand foot run.

[Br9es]

I would leave it stock , that is one sweet machine

[back in the day racing]

All I plan on changing is the drive sprockets to aluminum and adding one tooth to them.Putting on the cat reverse secondary. And maybe a comet primary. But I am going to save all parts that I change so it can be put back on. Thanks for the compliment of my sled.

[ski-man]

Adding a tooth to the drivers will make the stud clearance very close even with .700 long studs, the last thing you want to do is shred your tunnel  due to not enough clearance. I would gear it up in the chaincase and not the drive sprockets, the extra tooth on the drive axle wont make it turn that much more efficiently.

[back in the day racing]

I am running a 15-34 now. And I am going to a 16-34. Don't know if it can pull much more then that.

[Just Wondering]

Changing top gear from 15 to 16 is a 6.7% change.
If you changed the bottom gear to a smaller number of teeth a 6.7% change would have it at just over 2 teeth smaller.
But a one tooth change to a 33 tooth would be a 3% change. Not as drastic as a top tooth change.
I realize these numbers don't always seem to be what they suggest when applied dynamically to the running sled.
I don't know if this is even feasible.  Are  there other bottom gears even available?
Would other gears from other brands fit?

Keep us posted if you can.  I'm finding this very interesting to watch and learn.  I'm sure others are too.

[Just Wondering]

On another note,,,,,,that 250 is a beauty.
I too would keep it stock and it would be my show sled.
But that's just me.

Perhaps find another sled and build it up with all the low resistance features and mods you could ever want to think about.

My '72 Lynx, 250 and 300 Enticers are vintage le mans racers and the TXL Indy is a vintage snowcrosser.  All are mechanically tough but far from pretty or correct and I flog em like a rented mule.  My others are my show sleds.

Either way you've got a beauty of a Twister there.     

[OU81DOO]

All I plan on changing is the drive sprockets to aluminum and adding one tooth to them.Putting on the cat reverse secondary. And maybe a comet primary. But I am going to save all parts that I change so it can be put back on. Thanks for the compliment of my sled.

Don't waste your money on aluminum drive sprockets.  Take the front drive out and have the drivers trued up.  That will help and no where near the cost of aluminum drivers.

[back in the day racing]

I believe that there are two smaller bottom sprockets available. I talk to Lee Erickson the other day and he said to leave the drives the size they are and run the 16tooth top and maybe try a 17. But would also need a chain. Going to go to his place next week. My Merc was a show sled when I bought it. I  have always wanted one since my dad took me to the races at MN. State fair grounds back when the l/c came out. I bought it run vintage radar runs. Along with my srx.I just thought it would be faster. I do get along of complements at the races.And some even know who Doug Hayes is. It was signed by him at a show.And today I found out that Nssr is letting me have the # 5 for my sled. And I want to thank everyone that has replied to my post.My plan for the off season is to take it all apart and check everything over and reassemble and true everything up. We used to call it blue printing. A trick I learned from a article in snow week from Tim Bender. Right now I'm working on getting a tach for it so I can how it is going. It's hard to do anything with out. just need to beat 72.060 to get the speed record for its class vintage stock e.