[curta3531]

Back in 84 I bought a new 85 Formula. When you bought a Formula, you became a member of the Ski-doo Formula Club and you received some paperwork and decals and most importantly a diecast key chain token (pictured). I kept mine in my junk drawer all these years. LOL. That sled is long gone but I did pick up an 85 Formula Plus yesterday with 3700 miles on it. Truly a barn (shed) find sled. Mag side piston burnt but motor does turn. Very straight sled with minimal spider cracks in the hood. Track looks mint.

DAY 1: Began by vacuuming out tons of acorn shells and mouse debris. Gave it a bath and so far, so good.
Removed the seat (seat cover, plywood, and tail light assembly is perfect less the lens).
Removed the gas tank. (rotted grommet and fuel pickup, What a stink.).
Removed the airbox. Inside the airbox was perfectly clean. (rotted boots and air inlet rubber seal torn).
Removed exhaust. (All good).

 

[curta3531]

X2 on the rotten tubes.

Still has the shiny pan! Is it save able?

Very cool project

Yes, Very savable. I have not found a crack yet!

 

[curta3531]

Nice- I will be following. Word of caution the bottom tubes of the frame is likely rotted through and depending on your plan, you might want to pull the belly pan and fix it.

I recently pulled 3 PRS chassis apart and they all had varying degree of rotten tubes..

If you find yourself needing parts let me know as I have a bunch.

Yes. thanks. I have seen a few picts of rotten frames. Im hoping for the best but expecting the worse. And thanks for the parts info!!

 

[curta3531]

DAY2:
Removed the carbs. I will check that the carbs were installed correctly when I disassemble them. The main jets are different sizes for mag and pto sides. (The springs on those 40mm carbs are amazing. No wonder our thumbs cramped up.)
Drained coolant with no mess.
Removed the motor with RV tank and PTO installed. Of course more mouse lodging.
Took photos of harness and speedometer cable routing and attachments and removed the hood.


Removed exhaust. (All good).

 

[curta3531]

Gee...I might need a fuel level sending unit. The rust and corrosion in the fuel system is crazy. The arms and float rotted away and four out of five screws snapped off. I can drill and thread those inserts but will only do that if I can find a new sending unit. Anybody with a good tank or sending unit?

 

[curta3531]

The motor has a burnt piston front edge (mag side). I tore into that carb and found the needle jet in the wrong groove (2nd instead of 3rd) which would lean it and the idle needle was at one turn rather than 2. I need to get some wire gauges to determine main jet size but it is bigger than the PTO side which is correct. I cannot read the size on the jet.

 

[curta3531]

I will have a look, should have something. Tank is a bit hard to ship but maybe just the sending unit. I owe you a good deed lol. Looks like still something to grab onto there, maybe you can soak them with penetrant and be lucky enough that some will come out.

That would be so wonderful if you have one! I have the screws already soaking with Blaster. I need to get Marvel Mystery Oil. I used Marvel overhauling jet engines for years. Love that stuff. Smells good too. LOL THANKS Pete.

 

[curta3531]

I got out my magnifying glass to read some numbers and found that someone re-jetted the carbs. Does anyone know if a factory bulletin ever came out changing any of the specifications for the 1985 Plus. The 1986 Plus changes the main jets to 330 / 350 and the needle setting to #2 position.

 

[curta3531]

Here is what i found in the tank.

 

[curta3531]

More progress. As I disassemble, I keep a log for the assembly sequence. Found missing cotter pin on the top nut. Also the large piece of metal (third photo) floating around in the chaincase. Not sure why it is needed for the dipstick???? No visible damage


.

 

[curta3531]

Carb jetting 1985 Plus. Curta, I have a 1985 OEM Ski-Doo shop manual. The jetting listed is the same as your green numbers ( 330/380 etc). I have usually found shop manuals to remain consistent with original publications ( just my observations). Then I have the OEM Ski-Doo 80-89 spec book. I have usually found the spec books to list specs after a "change up". In the case of the 85 Plus the book does not say a change up, but...For 1985 Plus the spec book lists the same as your red numbers P300/M350, 224AA5, 40 pilot, DH2 on 2nd, air screw 1 T out, piston valve 2.5, idle speed 1800-2000
Edit...Just checked the RV disk for 85 and 86 Plus, both same at 132/52

That's the best news I could hope for!!!! THANK YOU for your reply. It sounds as though It took Ski-doo a few years to figure out the jetting. Even the 86 models had yet different jetting than the red or the green. I did rebuild the carbs to the "as found" configuration. If you have a chance would you snap a picture of the manual with the revised the jetting so that I can insert it into my manual?

On another issue, I notice Wiseco pistons are still available on ebay for 1986-88 but not for the 85 (see below). Do you know if there was a difference between 85 amd 86?

THANKS,

Curt

 

[curta3531]

Here ya go curta. Quite a spread in main jet sizes in 85, they narrowed the spread for 86 that seems more realistic to me.

So I am going to use the 86 configuration. I can always change out the 330 jet for the 300 jet if it runs rich on that side. Now I have to find a 330 jet. LOL. THANK YOU for the picts. Here is a link to Flicker which documents some of my project. I photo everything as I remove parts. Flicker is just a subset of what I have photo'd.

85 Formula Plus Project Sled

Start date: November 13, 2021

www.flickr.com

 

[curta3531]

So I am down to the frame assembly. I got a price to clean, blast, and powder coat the steel front end but I need to remove the tunnel. I am thinking of all options. Has anyone powder coated the entire frame assembly (steel and aluminum tunnel) without separating?

Curt Anderson’s albums | Flickr

www.flickr.com

 

[curta3531]

There is one hole about 1/4 inch in diameter. It is on the bottom of one of the tubes. Looks like it rusted from the outside-in. No other weak spots. Just curious, why did you put it together before the powder coat.?

 

[curta3531]

Hmmmmm. Never thought of the fitment of the tunnel to bulkhead. Ill have to really look at that. I was planning to use black rivets which can be purchased. BTW...thanks for you help and thoughts.

 

[curta3531]

Thanks. Any problem with alignment of fit? The first picture will not load.

I see the 7500 decal on the wall. Do you have one?

 

[curta3531]

Very nice. I did the same. I sold it to a Ski-doo dealer for his showroom. At least I can always see it.

1979 Blizzard 7500 Project Sled | Flickr

 

[curta3531]

Well, that was easy..... The rot hole is where the pan had been chafing on the frame. The powder coat place is going to weld it up.

 

[curta3531]

To answer post 36, the front frame is bare and somewhat rusty on the mating surfaces. Definitely coated after assembly at BRP. Have you ever noticed that almost all powder coat fails (peeling) start at the edges? It's not from dings or wear. It must be that it is very thin at the sharp edges?? It almost makes you want to paint the damn thing.

For those that have riveted a frame back together, did you use steel rivets with steel mandrels or aluminum rivets with steel mandrels?

I hope the new powder coat will cover up the damage to the bottom of these skis.... LOL

 

[curta3531]

I think the fuel pump is not viable. Worst I have ever seen. This does not seem to be just corrosion. The motor has a burnt mag side piston on the exhaust edge.

Here is the latest progress.....

85 Formula Plus Project Sled

Start date: November 13, 2021

www.flickr.com