Fan cooled buggies

**JagerDanger** · 06-08-2020 12:46 PM

Just this past week, I had sent up some cash for my dad to pick me up a snowmobile. Seller had it posted on Craigslist as a 1979 Arctic Cat Panther 440 (Panther 4000). Turns out, it's an Arctic Cat 5000, with a Suzuki 500cc fan cooled 2 stroke pre-mix. So now that I finally have an engine for my project, how well do fan cooled sleds do? I found that this sled back in the day had an optional left/right cylinder head temp gauge that went from 0⁰F and red/danger being 600⁰F. Since I now know what the safe range is, it'll make riding much better.

But I'm curious to know how have others faired with fan cooled sled engines on buggies?

**jimmyg** · 06-09-2020 06:28 AM

I remember MASCMAN melted a piston on his not long after he got his 440 going.

Edit: Looks like he has not logged on in 2 years.

**65chedderbob** · 06-09-2020 07:02 AM

I've had no problems with a 94 Ski Doo Safari 440 (aside from a pinched gas line that leaned it out and melted a piston, not a temp problem though) or a Polaris Trail 440. I don't have my temp sensor installed yet, but that range is good to know for the future. I've ran mine wide open down the road for a mile or so at a time many times in 50-80° temps and it's been just fine so far. I haven't even touched the stock jetting (not to say that you couldn't make it start/run better if you did, I just don't have a jet kit for it).

**JagerDanger** · 06-09-2020 11:03 PM

Originally Posted by jimmyg

I remember MASCMAN melted a piston on his not long after he got his 440 going.

Edit: Looks like he has not logged on in 2 years.

Could have sworn I had read that on his POS build can't recall for sure.

Originally Posted by 65chedderbob

I've had no problems with a 94 Ski Doo Safari 440 (aside from a pinched gas line that leaned it out and melted a piston, not a temp problem though) or a Polaris Trail 440. I don't have my temp sensor installed yet, but that range is good to know for the future. I've ran mine wide open down the road for a mile or so at a time many times in 50-80° temps and it's been just fine so far. I haven't even touched the stock jetting (not to say that you couldn't make it start/run better if you did, I just don't have a jet kit for it).

That's what the guage cluster says for this engine at least. Hopefully if nothing else it's a good baseline to know if it's running too hot or what not.

This is similar to what my sled would have

1892735_0.jpg

**odypilots** · 06-10-2020 12:35 PM

Jetting has been the biggest issue I've seen taking winter based engines and using them in the summer, often with different intakes and exhaust. Water cooling has it's place, and I believe in it's advantages, but fan cooled engines can live in buggies. Sorry, no examples come to mind.

**darwinpayne2000** · 06-10-2020 01:40 PM

A fan-cooled two-stroke makes for a lighter, simpler buggy compared to the liquid-cooled models, so it's not a bad choice. My 400cc 4-stroke Vanguard engine was fan-cooled and I never had any issues and I pushed that engine hard out on the sand dunes. When I talked to a guy about adding an oil cooler to the engine, he questioned my sanity. He said that it should never need one unless the airflow was severely restricted.

The comments I read in the past from people running fan-cooled sled engines is that you want to make sure the jetting is correct (a little rich doesn't hurt) and they typically didn't run it when it was really hot (e.g. 90 or above). I'm a fair weather rider myself. Anywhere between 50 and 80 degrees is my preference. When the thermometer starts inching up towards 90, I'm done.

**aschn** · 06-10-2020 01:46 PM

I have a two stroke 440 rotax fan cooled engine in mine, and I'm going to add scoops to the side panels to feed more fresh air to the fan. Some guys I talked to put tin enclosures around the heads (much like the tin work you see in air-cooled VWs) to keep the fan air flowing over the heads.

**JagerDanger** · 06-10-2020 03:03 PM

Originally Posted by aschn

I have a two stroke 440 rotax fan cooled engine in mine, and I'm going to add scoops to the side panels to feed more fresh air to the fan. Some guys I talked to put tin enclosures around the heads (much like the tin work you see in air-cooled VWs) to keep the fan air flowing over the heads.

Could you elaborate on how you are going to do the ducting for it? Just sheet metal fins more or less that direct air into the fan and fan shroud?

**ProtoDie** · 06-10-2020 09:43 PM

DSC00633.jpg
our first buggies were 440 snowmobile engines / fan cooled. engines lasted a year or two. they did not like summer heat and racing. rebuilt one after a pistons went out,,,,,,then rebuild lasted a couple months. then there was all the clutching education & R&D.
so we built new buggies with GSXR 600 engines. way happier,,, then switched to GSXR 1000 engines,,,, even better

**65chedderbob** · 06-11-2020 07:04 AM

Most fan cooled 440s come with shrouds already around the heads/cylinders to direct the air from the fan. I think he's just talking about some kind of scoop on the side or top of the vehicle that would act as a sort of ram air system at speed to provide some additional cooling while the vehicle is moving. I haven't needed to do this on mine but I've definitely thought about it.