Add a Primer to your sled
So your sled is hard to start because it sits all the time, or its really cold out. You're tired of yanking that cord a million times to get riding. One night when there was snow on the ground and my '71 Arctic Cat Panther 303 wouldn't start I got thinking there's got to be a better way.
Well friends there is a better way, its called a primer.
First lets talk for a second about
carburetors and the starting circuit. On the older Tillotson and Walbro
carbs when you want to start the sled you set the choke. The choke on
those carbs is exactly what it say it is, a plate that closes and restricts
the amount of air available to the engine. This forces the engine to
draw more fuel, which makes the ratio of fuel to air higher, and helps
the engine start easier. On Mikuni carbs when you flip the "choke"
lever you open the enrichment circuit adding more fuel to the existing
amount of air which accomplishes the same thing.
So what can you do? There are 2 common types of primer, one is the squeeze bulb primer which pressurizes the gas line, the other pumps fuel directly into the engine intake. The latter type can be subdivided into the push/pull and push bulb. Installation of the squeeze bulb primer is very simple, the hardest part is finding a place to locate the bulb. I'll cover the installation of a squeeze bulb primer in another article. I have one on my '70 Ski Doo and it works well, you may also have seen them on boats with outboard motors.
List of tools:
1. 1/8" drill bit and drill:
2. 4mm-.70 Metric tap
3. Flat head screwdriver:
Pictured above is the Tillotson HL carburetor on my '71 Arctic Cat 303. This carb is a little odd because it has a pipe between the carb and engine. I've seen this sort of thing on Kohler engines too but with the carb pointed straight up. Anyway for the purpose of this installation I pulled the carb with the pipe from the engine.
Then I drilled and tapped a 4mm-.70 hole in the pipe right by the engine and screwed in the barbed fitting and bolted the carb back up.
List of parts:
1. Primer install kit:
2. Primer barb:
In retrospect I should have located the barb more toward the top of the pipe. As it is the fuel line runs near to the clutch than I'd like. Once I've installed the primer in its final position its pull on the fuel line should keep things safe.
For now I've zip tied the primer in
the right footwell. Its safe there and not likely to get knocked around
while testing. Since this sled is a pretty good, fairly unmolested sled
I'd rather not go cutting it up and I was about ready to start making
a braket to mount the primer near where it is now when I happened to
take a glance at the sled's dash.
There, in front of my eyes was the word "prime" but no hint of a primer. It looks as though I could easily mount my primer in that panel just above the handlebars. I happen to know where theres a junker '71 and if it has its little panel I'll grab it and mount my primer in it. If it doesn't I'll make a new panel. Either way I'll put mine aside, I'd wager those panels got broken out pretty easily. It would be interesting to hear from someone who actually knows the mystery of the "prime" on the dash.
Whats the verdict?
Early tests indicated some part of this had gone horribly wrong and there was an air leak. The sled idled but died as soon as I opened the throttle. This basically sidelined the machine for the '04/'05 winter. Over the summer the Tillotson decided to stop pumping gas so I rebuilt it figuring that the old carb to block gaskets might have caused the bad running problem.
After rebuilding the carb I found I
had the same issue but I managed to adjust the carb to get rid of it. So when I'd been experiencing
the issue before it was really a carb tuning problem I'd attributed
to my primer installation without investigating fully.