rotax 503

disfunctionals · Post by **disfunctionals** » Tue Nov 15, 2005 5:16 pm

im building a rotax 503 for one of my race sleds. im doing most of it myself to save some bucks. im wondering if anybody knows of any specific parts or adjustments to make for max power.

Deleted User · Post by **Deleted User** » Thu Jan 05, 2006 12:50 am

First of all good luck! I have dealt with these motors and had nothing but trouble but thats just me. As for low cost power there really isn't any if you want power you got cost coming with it.

400brian · Post by **400brian** » Fri Jan 06, 2006 2:42 am

The Ultralight Aircraft community views the 503 as the best and most popular aircooled engine used.

But, they run 'em bone stock, and keep the rpms below 6500.
Parts shouldn't be a problem though.

jerryswiss · Post by **jerryswiss** » Sun Jan 08, 2006 1:22 pm

The Rotax 503 is a great engine, in my opinion. I have an '87 Skandik, workhorse sled with a 503 in it and it will pull four people (two on the machine, two on a cutter sled) up hill through deep powder (I live out west) and not bog down 1 rpm. A local sled mechanic I know says the 503's are bulletproof. As far as mods, I recently picked a used 503 out of a '78 Blizzard 5500. It has dual carbs and a tuned exhaust. My skandik has a single carb, I may switch to duals and see what happens. That is all I know you can do with an axle fan engine.

disfunctionals · Post by **disfunctionals** » Mon Jan 09, 2006 6:17 pm

yes they are bulletproof motors. bone stock it went like a bat out of hell,but you always need more. the motor is now complete and now im just tuning the clutches. its a lot faster than it was im very satisfied. oh and by cheap i meant labor. hp costs $.

Rodimus Prime · Post by **Rodimus Prime** » Wed Jan 25, 2006 4:26 pm

the late 80s 503 cranks are stronger built than the earlier years as they had a problem of cracking in middle of crankcase.