The hot one

[cliffo]

Hopefully there's someone on this forum who can tell me which cylinder on a 447 with fan cooling runs at the hottest temperature. I only have one cht gauge and I want to use it on the warmer running cylinder. I know, I'm lazy and trying to save some time and wrenching. It's on a quicksilver MX sprint. It's currently being used on the fan side cylinder.

[Dana]

Usually it's the rear cylinder (farther away from the fan) that runs hotter. However, with the side flow engine like the Rotax it's probably less pronounced than a Cuyuna which flows air from the front head to the rear.

Dana

[cliffo]

I'm at a quandary ,if I should put it on the coolest one to make sure I have enough warm-up to be going full power without seizure problems or the other way around to catch it from overheating. But I'm thinking when it gets hot they are both going to be fairly close on that. Too much thinking????!!!!!!

[crusty old aviator]

Try borrowing an infrared temp gun from someone, Fluke makes some real nice ones and most HVAC folks have them, and use that when running up on the ground to determine which cylinder gets the hottest. You can also shoot a laser at the exhaust stacks, about and inch or two from the cylinder, to see the differences in your mixture settings, etc.

[cliffo]

Good tip, Thanks

[cliffo]

I just went shopping on E-bay and got a laser temp gun for 12 bucks delivered. Wow. For that price I would have had one long ago. Temp range is -58 thru 718. Great for checking bearings and some other things,like the wife when it comes in the mail.