The 1970 season marked a turning point for Arctic Cat, not with a production sled, but through a behind-the-scenes factory race program. Select chassis were fitted with EXT-spec engines, tuned directly by JLO, Hirth, and Kawasaki under Arctic Cat’s direction. These weren’t dealer models; they were limited-run race sleds, hand-prepped for Arctic Cat’s top racers.
🏁 Quick Facts:
- Factory-installed engine mods from JLO, Hirth, and Kawasaki
- Limited builds: fewer than 100 per engine variant
- Open-pipe exhaust, tuned carbs, and aluminum tunnel components
- Set the stage for the standalone EXT lineup in 1971
With aggressive power, lightweight builds, and open exhaust, these sleds redefined what factory involvement looked like in snowmobile racing.
The following year, that philosophy went public: 1971 marked the first consumer-available EXT, and Arctic Cat’s transformation into a racing powerhouse was in full motion.
📸 Drop a comment if you knew about the factory-built EXT sleds before 1971. Bonus points if you ever saw one in the wild.
Recently, a customer/friend donated a 1970 Panther to me-said he didn’t want it to find a scrap yard. Lo and behold, it turned out to be a 1970 295 JLO EXT. Currently trying (slower than I’d like) to get it back up and in running shape. Tried to offer him something for it after discovering what it is, but to this day, he won’t take anything for it. I believe there were 94-ish machines made?
Yep you’re right.
How about if we sold them new? Does that give brownie points?
These sleds were so much fun and a real giant killer. The 340 Hirth mod pop had as his own machine that year, outran a 640 Ski Doo twin. After that got out the Pumas practically sold themselves. First year machines often had aluminum bulkheads on the mods/exts. His weighed 275 lbs dry and was easily pushing over 30hp from the factory modified single. Think John Deere Spitfire on Steroids….
At the risk of being a column hog, my apologies if this offends anybody. Perhaps some more importance is what the first year puma race sled inspired after it. The first year thunder jet designed by Dwayne Aho was a direct inspiration from looking at a 1970 Puma. This is mentioned in warrior of winter book. A few years later, Mercury was coming out with its first Snow Twister. In recent interviews, the team that designed that also went back and looked at the old Arctic Racer Puma and said “ Ok! Race sleds are getting too long and too fat for 1974. Let’s bring the 1970 Puma into 1975 and give it a serious update.” The rest was history. I never liked that Cat turned the Puma name into a bigger engined Lynx economy sled. It should have stayed short, hairy and mean.
70 Pumas and Panthers are probably my favorite vintage Cats. The Mod and EXT versions are rare up here in Canada, I think I’ve only seen a couple up for sale here over the past decade or so and I can’t recall ever seeing one back in the day when they were new. I have a 70 Puma Mod that came out of Pennsylvania.
Also wanted to add that I love the recent content on Arctic Insider, so many interesting articles and there is always something fresh to read. Thanks for the great work!
Sno Owl which model Mod do you have? I’m a native Pennsylvanian.
Mine is a 340 Hirth single. The engine had finger ports in the cylinder, boost ports in the piston and the head had been milled. I believe it came out of the Klick dealership and I suspect it had been raced back in the day. The hood had been cut for a megaphone!
Many years back when I was first getting into vintage racing, and while walking through the pits to see what was running at an oval race, I saw some guys running a 1970 Panther with a 399 Kohler engine. I told my then-teen-age son “I can’t believe anyone is racing a sled with a 399 Kohler, they barely had enough power to get out of their own way!” When they hit the track with that sled, they were consistent front runners. I was shocked! I looked those guys up later in the day and told them I was really impressed with how well they had that sled running, because I’d never seen one that ran worth a damn! They just gave me a funny look and then ignored me. I found out later it was a 399 EXT Panther! At the time I didn’t know Arctic Cat had built an EXT version of the 399 Kohler. Years later, I picked up a 1970 Panther with the 440 version of that Kohler engine. While cleaning up the chassis, I scrubbed up the ID tag, and lo and behold – it was stamped “399 EXT”! Apparently, someone had put the 440 in it. I hung onto it for a year or so while I tried to track down the original owner, and hopefully – the original engine. I got a few leads, but in the end they all turned out to be dead ends. I finally sold the sled and moved on to other projects, but if I could have located the original factory mod engine it would most definitely still be in my collection!
Yep, they made them. I found out about it back in 1998 when I did all that research for the EXT articles I wrote, but lucky you found one I’ve never seen one up close. They stuck a few of those motors in puma chassis too.