Ski Doo 521 engine - Snowmobile Forum: Your #1 Snowmobile Forum

kmhemi · 07-12-2006, 08:20 AM

I am working on a Rotax 521cc type 536. I bought this engine to use in a hovercraft.
My question is about the oiling system.
On the topside of the engine case bewteen the cylinders there is a large diameter oil line. There is another one on the bottom of the engine case. The manual says they are oil in and oil out. What are these for and where should they go? Do they run back to an oil tank? They dont seem to have anything to do with the oil injection system.
any help would be greatly apprecitaed.
Thanks
Keith

**smallengineguy** · 07-12-2006, 09:12 AM

They are oil lines to keep the rotary valve lubricated. They should go to a tank. The pump just cycles the oil through the tank and back to the rotary valve. DON'T run it without those hooked up!

kmhemi · 07-12-2006, 09:16 AM

Thanks for the quick reply. is the rotary valve pressure fed through the oil injection pump somehow or is it just gravity fed from the tank through the lines?
I hate to ask dumb question but I can't afford to make a mistake. These are not cheap engines.
I do appreciate the help.

**smallengineguy** · 07-12-2006, 09:56 AM

I had a 521 in a sled of mine. THe oil tank was bolted to the back of the engine and had the lines in and out of it. Check www.hlsm.com and pull up the microfiche on it.

kmhemi · 07-12-2006, 10:13 AM

Thanks again for the help. Looking at the microfiche it looks like the one tank supplies the oil for the injection and a gravity fed supply for the rotary valve. So I can just setup one small tank and run lines to the injector pump and the larger lines over to the rotary valve. I guess I am suprised that the valve isn't pressure fed. If thats the case the supply and exit lines to and from the rotary valve will be full at all times.
Thanks again
You guys will be alot of help on this project.

**smallengineguy** · 07-12-2006, 09:24 PM

No problem! Let us know how it goes!

swazichef · 08-16-2006, 01:29 PM

Good Day
I have come across your postings . I to am fitting in a ex skidoo engine into a hover craft . Have you managed to get any wiring or engine diagrams from any where ?

look forward to hearing how far you are along with your project

Graham

kmhemi · 08-16-2006, 02:24 PM

I am rebuilding a scat fiberglass hovercraft. It came from the factory with a 277 Rotax and the newer models got the air cooled 503. I wanted more power so I went with the water cooled 521. I have my mounting brackets all fabricated now and I have the original ski doo exhaust. All I have to do now is get a set of radiators and bolt it all up. I have already mocked everything up and the belt and pulley alignment is dead on. This thing will be a real blast. I purchased a factory service manual so any information you need I should be able to provide. The Ski Doo manual covers a variety of engines.
I have learned alot about these engines in a short amount of time. Reading the service manuals helped alot
Tell me more about your project.
Keith

swazichef · 08-16-2006, 03:21 PM

A Scat Hp ( one seater) 9ft x 5ft , Thats what mine is . I bought it on ebay a while ago . It was in good condidtion but did need some TLC . I have renewed some of the skirt finger pockets and refitted all the skirt clips .
It came with a 440 Kawasaki engine . That gave up on me while i was on the Suwanne river !! Lucky I had a friend in a boat near by who towed me in.
This engine the Ski Doo engine 521cc Rotax from 91 Formula Plus XTCE will fit and I hope with a bit more power give me a little more lift on water.
I havent got too far with the engine replacing yet still looking for a cooling system and oil pump etc but I dont think that will take too long to find. I am not too well up on the engine wireing if you have any info on that ?
One site you might find of interest is Welcome to Air Commander Hovercraft, Inc. - Home Page they stock alot of scat parts .
If you need the scat manual let me know I got one from the above . (bit basic) but mightbe of some help
Graham

kmhemi · 08-16-2006, 03:41 PM

Is your prop belt drive or gear drive? If you have belt drive I can send you pics and a template to make your motor mount. It took a good bit of time so I could save you alot of hassle. I will bring the service manual to work tomorrow and fax you the diagrams or scan and email them. This 521 will be WAY more power than you had. Did you go to the hover rally in chillicothe ohio ?

GrassPilot · 08-28-2006, 12:21 AM

Iam going to answer the original Question that was asked about the 521cc type 536 rotax engine,The large lines were connected to a small reservior to lube the ROTARY VALVE / WATER PUMP SHAFT AND CRANK GEAR ONLY..
The other reservior was for the oil injection system which was a consumable oil that was injected into the Carb base mount.This fuel /oil mixture lubed the rotary valve,plate and engine parts.
A little info about the 521cc.....get a 537 type engine 1986-88 best of the 521cc 44mm carbs,approx 90 hp single exhaust....with mild porting and (reputable) twin pipes and "207" rotary valve , jetted properly =130 hp.Using the old cross country"202" R/V specs(racing only) about 145 hp.The 537 type had bigger ports and a taller exhaust port.With extreme porting,exhaust and R/V modifications 180hp would be produced
GP

supercharged86 · 11-05-2006, 06:40 PM

Dear Ski-doo owners,

Newbie needs your help. I was reading the rest of this thread and thought I could find the answers to my questions here. Here's the story and possible problems. I was given a 1985 Grand Safari Luxe LC which as far as I can tell hasn't been started for a good 10 years. It was stored outside but luckily not on the ground so the undercarriage is rusty but doesn't look to bad. Unfortunately, there are a number of other issues; lost key, bent ski, damaged hood, broken windshield and damaged seat just to name a few. I won't mind spending the money to fix these other problems as long as I know it runs. I would like to see if she "fires" before moving on, which leads me to the basis of my questions. According to the engine plate, this sled is equipped with the Rotax 521cc type 537 engine. From what I read a few posts back the two oil reservoirs that are mounted behind the motor are the oil injection reservoir (large res.) and lubricating oil reservoir (smaller).

My first quesition is: the smaller reservoir has a feed line coming off the bottom but unfortunately is broken off and I can't seem to find where it goes (can't find the other end), where should It be going? What type of oil is used here?

My second question is: Is it possible to by-pass the ignition cylinder to find out if this motor has spark? Unfortunately, there is no key. The ignition has 5 terminals on the back of it, which are labled: Battery (heavy red), Solinoid (heavy red with green stripe), Accessory (double smaller red), Magneto (double smaller blk) and Magneto (double smaller blk with yellow stripes).

Third question: Since I don't know the condition of the injection system, can I pre mix the oil and gas? If so, what would be the ratio?

Likewise, there was mention earlier of OnlineMicrofiche Index that has microfiche data, unfortunately for me this website only dates back to 1987. Are there any other sites like this that would have information on a 1985.

Thanks for all your help in advance. Steve

**smallengineguy** · 11-05-2006, 06:43 PM

1) There should be a nipple or broken line in the back of the engine below the carbs. That's the input for the rotary valve. It uses regular 2 stroke oil in the tank (same as the large tank).

2) Luckily on the older sleds, all you need to do is unplug the key switch and you should have spark.

3) Pre mix on these rigs are 50:1.

P.S. I can'tfind any online microfiche older than 87 either.

supercharged86 · 11-05-2006, 07:41 PM

Dear Smallengineguy,

Thanks a million. I'll look there and try cranking it with the magneto wires disconnected. I forgot another question in the previous post. The engine compartment is absolutely filthy with an inch worth of oily debris on the belly pan. Can I use a hot water steam cleaner to clean this without getting into to much trouble. Thanks again for your help. Thanks.

Ps. My in-laws have a vacation home in Center Sandwich, where we hope to ride this machine If I can get her going.