ANOTHER SLED PROJECT... SPRINTFIRE #2

[SS440-80]

Beautiful skid!

Thanks Jason

Don't forget the limiting strap. I don't see it in the pictures.

I believed I could sneak in the almost done skid picture without anyone noticing that the straps where missing...

But today on my lunch break I mounted the straps (I use two) and took some pics

[SS440-80]

With the motor sand blasted and painted it's time to assemble it again.

First honing the cylinders



New cylinderbase gasket



New o-ring on the centre bearing on the crankshaft



Original Sprintfire-pistons. Used but in good shape.



Of course new needle bearings and crank seals



Top and bottom back together again...





Stator och flywheel

[acesillini06]

Excellent detailed pictures. Looking really good. Bring those Sprintfires back to life!

[jep_800]

Very nice work!

[SS440-80]

Thank you boys
I try to show a lot of pics. Maybe to many sometimes, but if they can help anyone it's perfect.

Did a couple of hours on the motor tonight.

First I had to extend the right ignition cable. Soldering and thick insulation


And new spark plug caps



Went trough the water pump and oil injection pump, making sure they work. Mounted it and the starter cage/ belt pulley



New oil lines



Starter



And engine mounting plate

[SS440-80]

The motor is almost ready to go back in to the sled, but first I have to make the chassie look better

The tunneln has been stripped from the original stripes by a previous owner, and then painted with some strange silvery paint that wont come off even with thinner. So I make it easy for me and wrap with same type of folie that the pros use on cars...

The aluminium above the fotrests also had the same strange painting, so I practiced on them.



Then the tunnel





Not to bad for a wrapping rookie

[TASKY]

I saw a Sprintfire once in all black, belly pan and all. It really looked nice.

[SS440-80]

I saw a Sprintfire once in all black, belly pan and all. It really looked nice.

A all black would be super cool But I don't think that a painted belly would look so nice after a season here with our narrow trails in the forrests... But the hood will be painted in high gloss black. If there will be any stripes.... I don't know yet


The foot boards on John Deere ain't by far so soft as on old Yamaha sleds, but the aluminium rail grip is so good and makes the board so much stronger so I put them on the Sprintfire anyway



Stabile

[SS440-80]

The original Sprintfire gas cap was in bad shape, so I bought a new gas cap that I had to shorten the gauge 5cm (2")



Then I made a new bottom for the compartment in the gas tank





Gas tank back on the sled






The seat had some cracks in the cover, but I made a quick repair of the cuts. My plan is to make another more sporty type of seat later, so a cheap repair of the old one will do for now.

[SS440-80]

The Y-pipe was rusty



and had some big sharp edges inside



Now the inside is grinded smoth and the outside is painted with heat paint

[SS440-80]

I mounted the skid back in the tunnel again, but I was not happy with how tight the track was. It's the big drive sprockets that causes this. And even tough the skid mounting bolts has been moved forward 6cm, I can't press the rear skid wheels enough to let the track pass freely.

So I have to make new drive sprockets...
I bought a piece of POM (other names are Delrin or Acetal) that I now will machine to drive sprockets with 9 tooth instead of the ones I have now with 12T.




First I have to make the ends of the peace straight

[SS440-80]

So now I have made a prototype...

I used the piece that was over when I cut of the two who's gonna be the drivesprockets. The left over piece is almost a half drive sprocket, just one millimeter to thin.



Made a mallet from a piece of wrapping foile



Just to get a image of the shape





Some thinking and measuring and then the lines for the axle was there





Cut of a metal pipe to get a 10mm ring to enforce the plastic where the axle will go in to the sprocket.



Some milling and some spins in the lathe, and the ring fitted like it was glued on



A metal plate to get a good line when I'm milling around the teeth





Sprocket now taken down in size to the right diameter. I decided that the calculated diameter for 9T with 3,29"/2 pitch and then 9mm taken away so that the track can curve around the sprocket



The rounding of the teeth marked



Teeth rounded and the centrum hole drilled



Drive shaft hole milled as close as I could, but the final touch I had to do with a rasp.



And here the "half" drive sprocket is mounted on the drive shaft. So now I just have to do the two sprockets I need for my sled.

[TASKY]

You must be very committed to that track to make custom drivers for it. Are the new sprockets around the same diameter of the stock ones so as to remain in the stock gearing neighborhood? Just an idea, a guy could make them in 2.52 pitch so a modern track with thinner rubber belting could be used? Maybe this would give a little less rolling resistance? I am envious of your machining skills.

[SS440-80]

Time goes fast when the winter comes early, and I have been riding my new Lynx Boondocker alot and also been out on my vintage sleds much










But I have been working some on the Sprintfire and on my ET440 to, but I have not taken the time to update the threads.


The new drive sprockets is done...





Yes, even mounted


And the skid is there too

[SS440-80]

One ski rubber damper was missing, but I found a rubber for a Ski-Doo that looked like it could fit with some modifing.







With the rubber dampers and ski spindles mounted it's time to make the skis look better...



Skis painted, new plastic ski skins and runners.



I am satisfied