Rotax 503 will this work

I got around to digging the rotax out and it appears to be meant for a snow machine. Can this be made to work on an airplane and if so what parts will i need?

 

You can use a belt redrive on that, but I would also check for bolt holes where a gearbox can be mounted to the PTO end.

 

I started pulling the clutch and belt drive off. This is as far as I got. I am going to have to find a gear puller. Looking behind the flywheel there are 4 bolt holes.

 

This is a 532 provision 4. Your crank is probably different. Change that and you may be able to use a provision 4 A gearbox.



bigger pic

 

I think a Rotax "A" box will bolt on any Provision 4 block. All 503 crank nose tapers are the same. All Rotax engines(other than 900 series) for that matter.

 

Weren't there some 3 bolt A boxes?

 

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If it's got (4) Holes it's a Provision 4 Case and you have (3) Choices, Direct Drive, Not recommended, Belt Drive, there is a guy on eBay selling Pro4 Belt Drives, or use Rotax Adapter Plate with an A Drive (A Drive Discontinued, Used A Drive is your only Option). Somewhere, I once saw a PRO4 to PRO8 Adapter Plate but never found out who made it. I got a photo of it somehwere, just can't find it right now. Case needs machined to use for Airplane use for Pro4 and Pro8.

If you live near a Skidoo/Seadoo Dealer, I would just take it there and they have the right Tool to pop off Clutch usually cheap $5. The right CLUTCH Tool is around $25.

Looks like CDI, does it Run, have good Compression?

Any Rotax 2 Stroke 1993+ is Pro8, except 277, and you can use Pro8 Gear Drive.

Any prior Sled Motor no matter how good it runs, if going on an AirPlane, I would recommend a complete tear down Inspection and all New Seals & Gaskets, and make some of the Upgrades Rotax did like Cageless Rod Bearings. New Pistons & Rings & Gaskets & Seals are cheap on eBay.

That is a Single Carb probably 30mm-34mm depending on what Sled Model it came out of. 503UL's used 36mm Carbs. Upgrading to Dual Carb makes 2-3 more hp than Single Carb.

 

I found that Adapter Plate, I have it labeled Kawasaki Adapter Plate, but I don't remember where I found it 8-9 years ago. I don't see why one similar couldn't be made for Rotax Pro4 Cases.

The Kawasaki Adapter Plate for Rotax A Drives was 3/4".

 

J Bird makes a very nice belt drive for these engines.

 

Here is the Pro4 Belt Drive. I believe you can get it with or without Electric Start. His Pro8 Belt Drives are $900 on eBay, I don't know what his Pro4 Belt Drives are Costing. If you used, www.searchtempest.com and searched from your Zip Code, it searchs both ebay and Cragslist, you could probablly find a good used Rotax Engine with a Gear Drive for $800-$1200, or with a Belt Drive.

 

I have a b gearbox with the 4 bolt hole pattern.

 

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B Gear Box(Better) is for Provision 8 Case's(Pro8). It doesn't use an Adapter Plate. A Drives used an Adapter Plate. I would keep the B Gear Drive, sell the Pro4 503 and find a 1993+ 503 Pro8 Engine. Almost all 1993+ Skidoo/Rotax's have a Pro8 Case. A 377/380 is the same motor, a 440/447 is same motor. 503F's were made up to around 2003, and the 2003+ 550F took it's Place, 380F and 440F were made up to around 2006-08. Overseas, there was a 380HO. 1993+ motors used bigger PTO Bearings(Better).

How much HP do you need and what do you want to put it on?

This guy seels a lot of rotax parts and I think he does the machining to the Case for Gear Drives also. Andy is his name.

https://www.ebay.com/itm/1989-2003-...mmit-MXZ-500/122769061408?hash=item1c959b3620

 

Finally got around to removing the flywheel this is what i found

 

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That's a Provision (4) Case, or PRO4, that use's the A Drive with Adapter Plate. It looks like it still needs to be machined for Adapter Plate.