Friday, February 21, 2014

Well thats not going to work!

After the excitement of riding the Polaris Cobra around the yard I figured I'd go all out and take it out on the trail. A quick ride down the street (love living in a redneck town) and I was off onto the trail. I didn't do too much riding, just to the snowmobile shop to hang out and show off. On the way home the headlight quit working which is a common occurrence on this sled, I need to play with the wiring some and see whats up with that.

Anyway the biggest issue with the sled right now is that its really loud. Part of that is the exhaust which I think may have had baffles removed, theres a suspicious weld around the side of the can but mostly its because theres no airbox. Carb noise is a particular whoosh kind of sound combined with a noise similar to the exhaust.

When I got the sled it came with an airbox but the airbox boots were trashed so I built some new ones, the existing clamp inner diameter was about the same as a piece of foam hose insulation so I built new boots with RTV using the foam as a guide. Unfortunately that proved to not fit the carbs so I spent a minute today and actually you know MEASURED things... Turns out the carb mouths are just about 42mm and I happened to have some 42mm radiator hose so my plan was to use RTV to graft the hose onto the existing stubby boots.

Here you can see how the old boots didn't make the gap to the carbs, it was hard to tell at first that the boots wouldn't actually fit over the carbs at all...

Heres my pile of supplies, the airbox, a piece of radiator hose, my micrometer for measuring and other assorted tools and cutters and whatnot.

I cut two short pieces of hose, the one for the PTO carb I cut a little longer than the inner, my intention was to sit the airbox slightly cocked to get away from the clutch.

Okay, confession time, its not gonna work, here you can see the carbs with my new boots installed, I even notched them to fit close on the carb but now I can see that to miss the clutch I'd have to offset the airbox half an inch to the mag side of the engine.

This will require some thought. My immediate thought is to buy a couple pod filters and it looks like I can get them for about $4 each. That would help with the noise a little and would also filter the air going into the engine but I think the PTO side is still going to be a problem.

The other thought I have is to take some PVC pipe and make my own airbox. 42mm is 1.65 inches so I should be able to take 2 inch pipe and fit the rubber boots inside, then mate that to a 4 inch piece of pipe in which I could install some baffles to reduce noise.

My final idea, and the one I think I'll end up with is to stop in at the shop and see what is available for airboxes, maybe they'll have something I can modify to fit.

Cobra rides again!

Okay its been weeks since I replaced the crank seals on the '79 Polaris Cobra and while I'd started it and run it around a little bit I'll admit I was kind of afraid to run it much for fear of it breaking again. That is of course a really lame fear, if it breaks it breaks, I'll fix it again and learn something. So finally after one of our run of storms while Angie was finishing up cleaning the driveway I pulled the Cobra out of the garage. I did this with some trepidation, the last time I'd ridden it I'd had trouble getting up on top of the snow and this latest batch was all soft powder, would I be able to even move in this? I'd sunk the Pantera the other day after all.

Well my fears were totally baseless, the Cobra with its low gearing is very quick off the line and with the good base we had there was no problem plowing right through the powder. I looped around the yard for awhile and then gave Angie a shot. At that point it was tough to get her off the machine, she rode all over. I even convinced her to drive we me on the back. Typically for her we got stuck, she hasn't ridden enough yet to build confidence in the use of power to stay out of trouble. Shes tentative with the throttle driving more like a car so she gets hung up often. I put her on the back and showed her how it was done which got her squeaking as we bounced around the backyard.

Our snow is excellent, probably 3 feet when we took the ride.

Thursday, February 20, 2014

Might be the end of the Ski-Doo

Went on a huge 5 hour ride last Sunday. Met up with some friends and rode all over the place. 3 different lakes, even made an unplanned open water crossing.

The old Ski-Doo ran flawlessly, the only problem was failure to go into reverse when I screwed up a water crossing and fell off the trail. If I'd been alone I'd have been in trouble as it was I had help and got back on the trail quickly.

That said this sled has some serious issues. A few years ago I bent the trailing arms and replaced them with aftermarket. At the time I was told that the aftermarket arms weren't as good as OEM and thats proven to be true, without even knowing I'd done it I bent the right side arm again. I plan to weld on a piece of angle iron so it won't buckle completely but I spent some time making a complete inspection of the sled:

Bent trailing arm
Buckled frame - from the first time I bent the trailing arms
Broken speedo - probably the plastic drive
Broken gas gauge - no idea
Broken thumb heater - probably just a bad wire
Torn seat - like all of them
No studs - its rotten on ice

The one thats a real killer is the buckled frame. I don't remember exactly what I did but just under the driver's feet the sled is creased. I don't think theres any way to effectively fix this, best I could do would be to drill and bolt some big pieces of angle iron into place to stiffen the frame. This would of course add weight. Alternately I could ask my welder cousin to weld in some aluminum angle brackets but the issue is that we're talking about an old, fairly undesirable sled. Riding the little goat trails we were on I was getting a real workout keeping up with the others on much less powerful machines.

A couple of the others in my group were riding Jag 440 machines (Arctic Cat Jag 440cc engine for the uninitiated) from around 1998 and I was very impressed. They're light, float good on the snow (we've got at least 2' and went through some drifts of 3' or more) and have plenty of power. I decided on that ride that I wanted one. Yesterday I went down to the shop and Randy let me try one and I realized I was right.

So Saturday I'm going to look at a '91 Jag, its a little older than the ones I was so impressed with and has a little less suspension but the price is right and the guy is going to hold it for me. I'd been looking at 2 up machines a lot earlier this year but most of them had been sold by the time I could go look at the sled. This guy is a champ...

We'll see how it works out, I feel like this is kind of a win, although I'm going to another modern machine its older than that which it will replace. 23 years old isn't quite vintage yet but it won't be long.

Friday, February 14, 2014

A great ride!

Last week we got 10" of powder snow but I was in California so no riding for me. Then yesterday and last night we got another 10", this time its heavier stuff and there was some rain in between snows which makes for just perfect snow.

After lunch I dug out the big Ski-Doo and headed over to the local snowmobile shop, he's got a good trail in but had packed snow against the trail into a huge pile. I'm not usually the trailbreaker and didn't judge how the pile was built, ended up on a pile with one ski hanging out into space. If the pile hand't been built so strong I'd have rolled right over.

Its hard to tell in the pic but the top of the seat is 6' off the ground...

Managed to get the sled off the pile by tugging on the ski and turning the machine down hill instead of rolling it. Then it wouldn't start until I realized I'd hit the kill switch when I thought it was rolling over. Heading back out I did an X-Games style jump back over the pile and fell ass over teakettle as the sled landed funny. Fortunately it didn't take off without me.

The rest of the ride was pretty uneventful until on the return trip I lost the trail on a frozen pond where the wind had drifted the snow. Out in the 20" unpacked snow the sled tried to bog. I got way back on the seat and piled on the power. The sled has a 670cc liquid cooled 2 stroke which makes something like 90HP which is plenty for a 700# machine. With the weight shifted back and the power piled on the skis lifted and we made it across the pond no problem.

So anyway, my 4th good ride in 3 years, planning on another ride tomorrow.