Winter fun - Project “Freedom” 440cc 2 Stroke 1054 Snowmotractor

[8ntruck 6,875]

Might be the nature of the 2 cycle.  To make torque, it needs to be running enough rpm for the pipe to start doing it's thing to start making power.

 

Just as a point of reference, what kind of rpm did the engine turn when the snowmobile started to move?  That is probably where it will need to run to start project Freedom moving.

 

Maybe using the variable pulley on the engine driving a jackshaft which drives the transmission through a belt clutch?  That way you would separate the variable speed  function from the clutching function.

 

Disclaimer - I've never messed with a snowmobile drive train, so this is a semi informed guess.

[Pullstart 62,193]

I drained the gear oil out of the transmission and mustered up a bunch of leftovers… 0W20 and 5W30, with a dash of Lucas oil additive.  
 

Moving it around, I realized every transmission bolt was loose by at least a turn or more!  Tightened up good n tite

 

 

[Pullstart 62,193]

For reference, the current belt is a 7478 which is 5/8 x 84”.  

Edited June 4, 2022 by Pullstart

[SylvanLakeWH 25,166]

13 minutes ago, Pullstart said:

 

I drained the gear oil out of the transmission and mustered up a bunch of leftovers… 0W20 and 5W30, with a dash of Lucas oil additive.

 

Should keep you lubed in all temps…

 

Question though… Should you post this in the recipes thread?

 

[wallfish 16,780]

10 hours ago, Pullstart said:

For reference, the current belt is a 7478

Is that engine pulley angled on both sides? The one I have from a torque converter is Asymmetrical so finding longer belts with a flat on one side is tough.

[Pullstart 62,193]

Just now, wallfish said:

Is that engine pulley angled on both sides? The one I have from a torque converter is Asymmetrical so finding longer belts with a flat on one side is tough.

Yes, it fits the WH belt quite well   The snow machine tc is different than a go kart tc for some reason… but for a good reason!

[wallfish 16,780]

4 minutes ago, Pullstart said:

The snow machine tc is different than a go kart tc

Thought so, I need to find / get one of those pulleys. Was also thinking about using just a half of one of those threaded type variable pulleys with the action half of mine

[Pullstart 62,193]

1 minute ago, wallfish said:

Thought so, I need to find / get one of those pulleys. Was also thinking about using just a half of one of those threaded type variable pulleys with the action half of mine

The snowmobile engine has a tapered crank FYI but you could likely bore it and key it.. 

[Pullstart 62,193]

Shifting gears from the new tiller tractor, I need to make this start, roll and drive.  I welded a 3/4x3/16 bar onto the bottom belt guard tabs with some downward flare on each end.  I bolted a tab onto the top and it stopped the belt enough with the parking brake set to fire it up!  Woo hoo, big issue fixed!

 

I’d like to say I’ll get the belt guard fabricated completely before the big show, but we’ll see.

 

 

[Pullstart 62,193]

I swapped in an 83” belt and added a belt stop on the idler.  

[Snoopy11 5,714]

On 6/2/2022 at 10:10 AM, Pullstart said:

5/8 x 84

Kevin... if you knock that down to a 1/2 inch belt... you would be able to buy me one for the 800 Special...

 

Mine takes 1/2 x 84...

 

Don

[Pullstart 62,193]

Just now, Snoopy11 said:

Kevin... if you knock that down to a 1/2 inch belt... you would be able to buy me one for the 800 Special...

 

Mine takes 1/2 x 84...

 

Don

Costs almost as much as racing seats 

[Pullstart 62,193]

I started building the double shear front casters.  I started with some 5/8” round bar, cut and drilled them into bushings on the lathe, then started cutting and welding.

 

Momma is out of town helping her little brother PFC Sensiba drive back to Southern California… so extra shop time for me.  Like last night’s tiller project, I’m hoping to test drive it tonight!

 

 

[Pullstart 62,193]

The wheels and brackets might look a little out of place, but I bet they’ll function just great.

 

I need to air up the tires and see what happens!

[Pullstart 62,193]

Welp… it moves.  For a tiny amount of time.  Then it runs out of torque.  Then it dies.

 

I think I’ll go back to a stock-er transmission pulley.

[Snoopy11 5,714]

17 hours ago, Pullstart said:

I think I’ll go back to a stock-er transmission pulley.

Any way you think that you could go bigguh on the engine side?

 

Don

[Pullstart 62,193]

2 hours ago, Snoopy11 said:

Any way you think that you could go bigguh on the engine side?

 

Don

that’s part of my problem.  Looking back, I started with about a 4” engine pulley and a 6.25” transmission pulley.  Now I’m at about 6 or 6-1/4” engine pulley and 2.65” transmission pulley.   

[8ntruck 6,875]

In other words, you went from a 1.56:1 drive ratio to a .42:1 drive ratio.  That reduces the torque delivered to the transmission by a factor of 3.7.

 

The 440 2 stroke probably does not have the same low end grunt that a Kohler has.

[Pullstart 62,193]

19 minutes ago, 8ntruck said:

In other words, you went from a 1.56:1 drive ratio to a .42:1 drive ratio.  That reduces the torque delivered to the transmission by a factor of 3.7.

 

The 440 2 stroke probably does not have the same low end grunt that a Kohler has.

That’s from start to current.  In the middle somewhere, it was doing quite well.  2.65” trans pulley and 4” engine pulley didn’t last long, but it was because of the belt being too loose and too much slip/burn.

[Pullstart 62,193]

I had a great chat with @8ntruck just now.  I truly appreciate your time Bill!  We decided that a 1 to 1 ratio of pulleys will yield right around or at least a safe 20 mph.  Add the 3” taller tire and it’ll be quick and reliable.  Not the fastest, but I’ll get there.  Back to the 6.25” hydro pulley and I’ll cut a junk belt in half to assist measuring a new one!

 

 

[rjg854 11,247]

[Pullstart 62,193]

8 hours ago, rjg854 said:

I cut it twice and it’s still too short!

84” (in stock) and 85” (just bought) are too short.  Gall dang.

 

 

 

[Pullstart 62,193]

Now we’re talkin’.  I need some guides / stops and I should be able to fire it up for another spin!

[Pullstart 62,193]

It goes!  Still not fast, but it goes!  I’ve come to realize it’s good enough for the show, but not near fast enough for the snow.

[8ntruck 6,875]

I wonder if swapping from the 3 speed to a hydro transmission would get you more speed?  The hydro would give you a 'low gear' to start up with, then allow you a 'higher gear' for more speed while still keeping engine rpms in the power band.

 

Then again, pump driving speed limitations would probably be a limiting factor....

Edited June 7, 2022 by 8ntruck