Just another barn find '72 400

[Curlymurt]

Figured I'd give a little update...

The fuel lines and getting this thing to run again was my newest issue. It ran when hooked up to the gas tank, but not when hooked up to the fuel tank. I had a robe time telling why or what was occurring, so I replaced the lines with the yellow tygon, 1/4" inside diameter. It was actually flimsier than I thought it'd be but bc everyone else uses it, I figured why not.

Once that was plumbed, I found one of my issues was fuel disappearing from the line. So I ordered a new check valve and it still disappeared. Ahhh! I decided to take the check valve apart for giggles... Not like it worked anyway... Behold! The flapper was actually too big. So I dug out my old check valve from the trash and too it apart. I was able to use pieces from both to make a valve that actually works, but I'll be adding a primer in some way. I'm thinking of using a marine inline fuel bulb.

While I waited for lines, filters, and valves to be shipped, I took to the exhaust manifold. I've got one joint that moves and the other is seized from rust. After some heat, pb blaster, and a big freaking hammer, it remained seized, so I'll function with just one flex joint.

Once I get the primer bulb in, I should be able to button up the sled and call it done (except for a few cosmetic parts). It runs a little rough, so I'll need to dial in the carb a bit but that's difficult to do without a tach so I'll have to wing it.

[Curlymurt]

I've got all the parts back together and fuel finally flowing through the carb. The first snow is on the ground and the sled isn't ready for prime time. It may never see its time.

I've got a mismatch of parts and its started to add up. Most of it was already on the machine when I purchased it. The secondary clutch and shaft are wrong. In turn, the wrong belt size is on it. And due to both of those issues, only the primary moves when ramping up speed. The secondary never opens, but isn't frozen in place either. That really limits the top speed. The carb has at least a non-original style of metering diaphragm. I'm losing gas out the front of the carb, or get no gas at all. Can't adjust the idle to save my life. The track bolts are different, so I can't adjust the track properly. I'll try to source those from the local hardware store. It'll probably get tooled on a little more this year, but in reality, it'll also probably sit in the shed for another couple years. It's disappointing and tiring, but I've learned a lot about these sleds and what to look for in the future. Hopefully my struggles will help someone else getting into vintage mid-mounts... I've certainly been helped by the struggles of others. I always think about picking up a model closer to the 80's that's liquid cooled, but then I see a photo of a mid-mount and I'm sold on the mid's again.

[Curlymurt]

I decided to come out of my frustration born pity party, and I've been back to work on the sled.

I realized that after studying the diagrams the job of the needle isn't to allow fuel to flow; it blocks the flow. Once I had that understanding, it made adjustments a little easier. I've only taken apart the carb 287 times, and gone through a pack a new stainless screws by trying to torque them down to spec. Anyway, once I had no fuel pouring out the front of the carb, it was pretty boggy, so I used more of a 50:1 gas mix and made a new foam filter for the intake silencer (which the Deere manual says is also to catch gas coming out the front). It seemed to run a little better but still boggy. On the bright side, I'm down to nothing more than a five minute cycle time disassembling the carburetor and putting it back on the engine.

I was planning to make our annual Wisconsin guys trip without my sled, but then we found out another friend was going, thus we'd be short a sled. So, I scurried for two days and ended up paying the $108 to my local Deere dealer for a brake band (the metal and friction material had separated). I struggled a bit to get that on in the correct orientation because it looked a little different than the original. I did do it without removing the secondary or other components. The brake was so tight that I needed to add a little scrap metal extender (and because I installed a different brake lever) just to connect the pieces.

So, we made it to Wisconsin with my spiffed up looking sled. The trails were in pretty rough shape, but open. I beat the tar out of the bogies and had gas flipping out of the gauge because the top was cracked to pieces. We ultimately made it 25 miles on the first ride, but after going wide open throttle to no throttle, I'd get a backfire or pop. I tried not do just drop the throttle for the most part. Then, my brake finally took it's correct shape around the disc, so I was able to remove the extender and readjust the cable. It stops as it should now.

I was able to get up to an estimated 55mph, but I've got a bouncy speedometer, so I went based off of what the other riders were telling me their speed was.

In fact, in the middle of the 10-12" snowstorm that hit northern WI, I took it out for a couple miles of fresh powder riding and... I loved it. I will most likely never that opportunity being in central Indiana. The sled is so easy to whip around without feeling like it's going to randomly throw you (I do have ski extenders) like some of the newer sleds. I was pegged at full throttle and sliding the backend from side to side just because I could. I wouldn't do that on hardpack snow though.

The carburetor ran ok, especially after a small high speed needle adjustment. It's still a hard start when cold, which I thought I fixed with my primer bulb) but it was super easy after it's warm. And, surprisingly, it ran without the choke. I'd only use the choke to start it and then immediately drop off of choke or it'd die. I found the definitive need to actually ride the sled for testing, and not putting it up on the blocks; again, it's going to be difficult in central Indiana.

The great news! I didn't detonate my engine.
The bad news! I need to rebuild it.

After the 25 miles, I found a leak where oil had been pushing out between the head and the crankcase. That's most likely the source of my backfires after WOT. I decided if it blew up in the middle of the trip, oh well, it's a chance to upgrade to a 440 engine. Since I wasn't so lucky, I'll take it apart, read the forums, read the service manuals, and ask you all a bunch of questions as I try to rebuild it. Who knows, maybe a different carb will be in the works, too.

Overall, I had a blast on the trip. Rode the sleds a bit on the trails and from bar to bar. We ice fished every day but one in our new 8x10 popup shanty. We thought we'd be towing my sled at some point, but instead it was a 2016 Artic Cat after it spewed all of it's gas out of the tank from a broken or ripped line. We hit the casino only once; that's a good thing.

Happy riding!

[SS440-80]