Ski Doo FormulaS 380 Worth turning into a Boondocker?

[AZ800]

Just picked up a clean 97 Doo Formula 380 fan for my 7 yr old this winter. Only experience with that chassis was a buddies 670 formula back in the day and all I remember was not having a choke sucked, temperamental to start and it was the roughest riding out of all our sleds at the time.
Can get a screaming deal on a 136x1.25 track and some rev skis. So only about $200 on top of that to extend the track.
Want to ditch the crappy bars too but the post is so laid back that I dunno if a pivot riser and some straight bars would do much or not.
Also any idea of a narrower seat that would mount up halfway decent and maybe be lighter than the couch that's on it?
Anyone run one of these?
Is it worth doing a bunch of work to it or just let him ride it as is?
Not sure if it will be a decent handling chassis for this or not.

 

[volcano buster]

Not very many of those around in this part of the country. A buddy of mine rented one for his gf and she had a ball on it. We were running mostly groomed trails so she kept up fine. She wasn't very big so that was plenty of sled for her. I think it had the electric reverse which was a cool feature as well for the time.

If you can get the steering angle figured out I think the rest of it would fall into place. I'm not sure I would get too excited for the seat upgrade until the kid has enough inseam to justify a taller narrower seat. Upholstery shop should be able to help you out real easy. Or watch for a seat/tank from a Rev at a swap meet.

I've got a 340 Polaris and I put a 136x1.25 on it last year and was pleasantly surprised where it would pack my kid and myself on it (300# combined weight).

 

[skidoorulz]

If I did anything to it at all I would just go with a 1.5 inch 121. Let him ride it a year or 2 and find a REV 550 summit for him. A 16 year old sled is not worth dumping a bunch of money into it. If I remember right the 380 was a single carb motor, surely wouldn't have enough power up high to turn the track worth a darn

 

[AZ800]

Yeah not looking to spend a ton of $ on it but can do the long track and skis for under $300.
It is a dual carb motor and will not be run at hi alt. 0-4000' here in AK and WA when we move back.
Seat is decent shape so may just hold off on that.
I "think" it will spin the 136 ok. If not I have some room to gear it down. 21/49 currently iirc.
If I didn't have a line on the track and skis for $75 I prolly wouldn't even do it but sounds like a fun project and I know the boy is going to try to follow off trail. He already does on the M7 given the chance.
Plus he's only 50ish lbs so it should float good with him on it.

 

[AZ800]

Wish I could ride it first to gauge how well it pulls but by the time the snow flies there won't be any time to do the work to it.

 

[volcano buster]

I picked up gears for mine in my spare parts bin. I went as deep as I could go since it won't have the power on the top end to really wind out with that much lug. I left the clutching alone and it was actually pretty fun in knee deep powder. I think it would handle more, but that is all we had that day.

I picked my track up for $95 and a rear bumper with covers for another $15. I had the rail and tunnel extension so that part was free to me.

Good luck.

 

[AZ800]

Well, just picked up a 136x16x1.25 track and some Doo dual runner skis last night for $75, and the guy threw in an almost new Klim backpack! score!
I can get the rail and tunnel extensions for under $200 so looks like it's a go.
I realize it will prolly need to be geared down but will see how well it does on a shake down run before lookin for deeper gearing. If I do gear down though, will try to max it out. I'd rather have it spin the track at 30 mph with authority than look for any sort of top end out of it.
Should make it a fun little sled!

 

[Escmanaze]

video

This sounds interesting. I look forward to seeing some video in the winter.

 

[AZ800]

Between 2 kids in football and a little issue with my Cat (wheeler) not being able to swim, not much progress! Haha.
I've got most of it tore apart save for removing the driveshaft and old track.
Will keep posted on progress.
I've always wanted to build a little boondocker for the kids. Stumbled on a fully set up Trail RMK last spring for the older boy, a deal too good to take on the work myself. 144x2 track, shorty seat, Simmons, mtn bar, nice tunnel ext, etc. It will be quite an upgrade from his '80 Trail Cat and I hope the little Doo will keep up off trail too.

Really would like to find an economical alternative to the 20lb "couch" seat on it now. Not a very good upholsterer, but considering the PO of the 550RMK just cut down the OE seat, tookoff the storage area, built up the foam a couple inches and recovered it, I may look into doing that. Unless there are any suggestions for a newer model OE seat (any brand) that wouldn't look like a total abortion mating up to the tank.

 

[H1Pilot]

Cool project. I'd love to see the finished product. It should be a sweet ride with 50# kid on it.

 

[AZ800]

Thanks H1. I'll get a pic or 2 up once it's put back together. Nothing too earth shattering now, looks like an old sled in pieces, haha.
On another note, anyone ever re-pack sealed idler wheel bearings?
When I knocked out oneof the bearings while taking apart the rear skid, the dust boot popped off and they appear to clip back in and seal up. Bearings are in good shape. Sled appears to have really low miles, speedo broke, but judging by the overall condition. Grease is crusty and shot in the bearings but I repacked a couple and it seems to work.
Cheap parts I know, have always just replaced them in the past but why not just repack them??

I'm also considering porting the new track. It's a big heavy track for a such a little machine and the track is pretty much new too, so real stiff. Kinda gave up on porting the last couple tracks, machines, but think it could really help in this case jsut making the track more flexible and getting a little more HP to the snow.

Just wating on the extension parts now.

 

[volcano buster]

When I had the long track skid out from under the 340 and the SnoScoot I popped the side covers off the bearings and pushed some grease in. I did clean them up first and made sure they rolled good otherwise they would get replaced. Apparently I put more grease than they would hold at speed according to the sling marks.

 

[AZ800]

Well it's all tore apart waiting on a couple extension parts for the long track and for me to finish porting the replacement track. I've given up doing this on my newer sleds but figured it would make a more noticeable difference on a low hp machine.
Rev dual runner skis fit up well and narrowed up the powder stance by about 2 " while actually increasing the trail stance slightly due to the outside ski skags.

It's got 19/44 gears in it now. Seems pretty low to me, 2.31 final drive ratio. Can I go much lower? Not sure ill need to. Plan on running it first before deciding if it needs geared down. Hoping the extreme track porting frees up enough hp to make it pull the 136 track like it did the 121.

 

[volcano buster]

How heavy is the pilot?

 

[AZ800]

The pilot? Haha
He's 7. 60 lbs with his gear on, if I put a couple rocks in his pockets!

 

[volcano buster]

I think you would be fine with your current gearing.

My thought is that the engine won't typically have enough power to fully spin that track like a larger engine would so it just needs enough power to pick the track up in the back and lay it down in the front so it can drive over it again.

!!

 

[Reeb]

We did something similar years ago. We ended up with 17/44 gears. With a rider that small, and +/- 40hp, you'll never have a problem with a 17t top. Just make sure you use a chain that is proper for it. Doglegs are the Archilles Heel for chain longevity.

We actually found a tank and seat from a MXZX S-Chassis race sleds. The tank and seat aren't as big and bulky as the stock ones usually found on the S-Chassis sleds. This helped the rider move up closer to the handlebars quite a bit. (I know it doesn't look like a problem, but the fact that the seat and tank on the stock sled are so high up, when riding, it's actually quite hard for kids to ride that far forward. They 'highside' quite easily)

As for the seat, narrower is definitely better for small kids, I built my own seat for it using closed cell foam sheets, however I've seen guys hollow out the stock seat and replace the guts with pool noodles, then re-upholestered tighter to make it look like the seat has been narrowed. The back hump was also cut off but rear storage compartment was kept. 8" bridge and tapered down was just about perfect for my little brother when he was that age/weight.

Another cool trick is to mount a platform on the running boards to give your little guy some leverage. That's the biggest problem with kids and trying to maneuver full sized sleds.

Narrow ski stance is always a good start, glad to see you've addressed that.

And a mountain bar, however useless for most adults, helps the small people out tremendously until they figure out how to throw their weight and use the throttle to get the sled to go where they want. Also, I'm not positive on the throttle, but upgrading to a dual-stage throttle helps kids a ton as well. Either that, or a A/C style lever from the same vintage as they are longer and flatter.

Also, the biggest performance gain is a new belt. The belts for these things are very soft and wear out quickly. However because of their intended function, nobody really notices a lack of performance because....they aren't performance sleds. But fresh belts help tremendously.

When it comes to the steering angle etc, you can move the fuel tank and seat forward quite a bit if I remember correctly. Moving the steering to a more vertical position. Also, narrow handlebars help lots as well. Not ridiculously narrow, but narrow enough where you're young'un can stand on one side and be comfortable reaching over for the throttle. It's damn near impossible to learn how to handle a sled when your weight is off center because your bars are too wide.

Have fun! These things were severely underpowered, but a quick 550f motor swap and it's a whole new sled once your kid is ready for it.

That sled I described was for a customer/friend's kid. We did something similar to my old '99 Snopro 440f for my little brother. He rode it like this for a few years. Had a 121x2 BigHorn track and 17/43 gearing. Absolute RIOT to ride! This particular picture was taken on the trail up to Turtle Mtn in Revy where a group of guys honestly thought we choppered the sled into the riding area cuz they didn't believe that sled, with my little bro riding it, could make it that far into the backcountry.

 

[Reeb]

Here are the platforms for the runningboards I was thinking of. Most kids that race sleds use these until they gain some height. You can kind of see the stock edge versus the platform itself.

And of the seat/tank combo I was talking about as well.

 

[AZ800]

Thanks for the tips Reeb.
I had one of those old MXZx's. Was going to make a little boonie sled out of it, but a move to AZ nixed that idea. Prolly hard to find that setup, but I'll keep my eyes peeled, no better place than here for snomobile salvage. I swear AK is where sleds come to die!
Yes, the tunnel/tank/seat is extra wide especially compared to today's sleds.
The running board platforms is a great idea, just what he needs!
He's real comfortable on a M sled with a 2010 seat on it for pretty much those reasons. Narrow seat up front and the footwell braces that he stands on when riding, to get up higher.
In the meantime though the seat/tank position may have to stay the same.

Belt is brand new and clutches are real clean, work well. Odometer is messed up on the sled, but by the looks of it, can't have more than maybe 1500 mi on it.
Got the "5 port" track back in it, looks like the 16" track will clear ok.
Handlebars are a little goofy. Rolled them forward a bit to raise them. It'll work for a little kid. The upswept angle would drive me nuts though. I see a couple hundred $ bills in moving the post, new bars, grips, riser, handwarmers, etc, even with some of the spare parts I got laying around.
It does already have a 2 stage throttle though and that's good. The last half is a stiff pull. Will keep him from holding wfo for too long!
Need to address the brake lever and see what I can fit up. He cant even touch the lever with hands on the bars with that big old plastic lever. Need to do a little salvage yard shopping or bend this one..something.

Just waiting on the extension parts to show up. I think they are coming by pony express!
And the hood needs the old 90's purple stickers removed and polished out. Got some new killer bee grafix for him!

 

[Reeb]

A new bar set-up can nickel and dime you for sure. However RSI has some cost friendly bars and everything can be purchased thru them if you end up going that route.

Hydraulic brakes would be ideal for your boy. I'm guessing it has the old mechanical style?
Salvage yard has to have something you can use....as for the throttle, perfect!

And a note about the brake, now that I think of it. I was always told never to use my brake. If I was following too close or going into a corner too hot....that was my fault and I shouldn't have brakes to fix my lack of thinking. Tough dad eh?

He did have to drag me out of the willows and ditches more than a few times, but all in all, I think I'm better for it now.

It basically showed me to anticipate much more than the usual guy, and get ready and setup for hair-raising situations. Besides all of that, it taught me never to touch the brakes while going downhill. (More advanced maneuvers/hills that do require the brake - not withstanding)

When I did use the brake I literally just wrapped my whole hand around it and pulled. Again, this helped me to rely less on the brakes and more on technique and anticipating. This was a STRESSED part about teaching my little brother the basics of sledding, and specifically mountain riding. Because he had a shorty lever with Cat Wilwoods, he was on them all the time. It took more than a few creative measures to stop him from using them constantly.

Can't wait to see this little rocket you're building!