1971 Arctic Cat Panther 440A    

Toward the end of last season this sled was giving me warm starting problems. It ran fine once started however. Compression has been   down for the past couple of seasons, and even after installing new Wiseco pistons and rings last year, the compression did not improve. So, this fall I tore the 440 Kawi down once again to see if I could find the cause of the problems.

One problem became apparent immediately. Klotz is not a good storage oil. I ran R50 last season and fogged the engine at layup. Still, there was quite a bit of rust forming on the crank throws. Next, I found the Wiseco pistons were quite loose in the cylinders, .008" at the skirts when they were .003" when installed. I measured both cylinders against a new one and found no wear or out of round, so I guess the pistons themselves wore quite a bit. There was almost no blow-by though, indicating the ring seal was good.

Over the years I have been frustrated with the wiring on this sled. It is hard-wired to the engine, so every time I have to take the engine out most of the wiring harness has to come out with it. I had the ignition system from a '73 Panther (engine connects to the wiring harness with a plug) so decided I would transplant this ignition and wiring. I also wanted to swap in the '73 coils, thinking the coils could be causing the warm start problem. Should be a simple swap, right? Well, I found out that in '73 Arctic changed ignitions from Mitubishi to Kokusan, and it's a 100 watt system compared to the original 75 watt. It was a bolt-in swap (stator, flywheel, and coils) but the wiring is different and requires a voltage regulator. Fortunately I still had the entire '73 harness including the regulator. I studied wiring diagrams and sought help from Cat guru Paul Wustrack. I'm not great with vehicle electrics so it took me a couple of weeks of studying and planning before I took the plunge and started cutting and splicing. Much to my surprise and relief, everything worked first time without any issues whatsoever. I can now unplug my engine, making removal so much easier. Time will tell if it improves the starting.

I had one new OEM piston and a very good condition used one. They measured spot on at .003" skirt clearance. I bought new SPI rings and installed them. Alas, they did not help my compression issue at all. At least not now. They should get a little better after breakin I hope.

I found a guy who had NOS Wiseco gasket sets for this engine. I was very impressed with the quality, noticeably better than the Winderosa gaskets. I now have a couple of spare sets on the shelf as well. Thanks Paul Camden.

The last issue I dealt with was timing. The '73 T1B timing spec was .005" btdc as compared to .015" for the '71 T1A. I consulted a couple of Cat experts on this as well. I decided to set timing at .005" and see what effect that has.

Rust on the crank. Lesson learned, run something other than Klotz in that last tank of fuel.

'73 ignition in place.

Going together.

After years of being relatively problem free this sled stranded me two times and nearly a third time on the trails last winter. The first was a burned piston on the PTO side. Next it lost spark on one cylinder due to a faulty condenser. Then it became very difficult to start, which I believe is due to low compression. I'll need to pull the top end before the coming season and see if I can rectify that.

This sled just keeps on running flawlessly. By far the most dependable of my "fleet". The only problem I had this season was a broken rear spring on the skid frame. Oh yeah, there was one problem when I ran over a snow-covered something-or-other and bent up the right ski, but that was my fault.

The Salsbury 910 clutch works OK, but I want to do a little experimentation with arms and springs to get the RPM's up just a bit. I found a source for NOS arm and spring service kits. I plan on putting in the stock kits that came on the sled originally and then work from that known baseline to get it operating as I'd like.

I did experiment with the round shaft Cat clutch late last season. The engagement was too high, and RPM's were high throughout the operating range as well. Add to that the complexity and maintenance requirements, and I'm just not real happy with it. I got a used Salsbury 910 (original clutch that came with this machine) from Dan Tomlanovich. I plan to clean and refurbish it and install it for this season.

I pulled the engine and discovered damage to the chrome lining in both cylinders. Time for a major overhaul. I replaced both cylinders with NOS items, and put in new rings. I also replaced the PTO and mag side crank seals and the O rings on the center split seal.

Removing one set of three weights from the Duster clutch sure had the desired effect on performance! The first time I had the sled on a wide, flat, groomed trail, I cranked her up to where the engine was singing along at a good sustainable clip, but not maxed out. I was shocked when I looked down at the speedo and saw I was ripping along at 60 MPH! It had more to give (well, not a lot more) under these conditions, except the handling at anything faster would be a bit more exciting than I care to experience. I suspect I'd get maybe 70 per out of the old girl on a road. 

One side effect of squeezing the throttle to the bar at these speeds is a very noticeable odor that I believe is the clutch pucks beginning to melt. Backing off just a tad eliminates the odor immediately. I've read that the Duster is designed for engines up to 35 horsepower, and that's just what the 440 Kawi is rated at, so I think I'm right at the ragged edge. Could be time to experiment with the Cat clutch.