79 Drifter 440 Diagnosis Help Needed: Excited Newbie Alert

[MillerTime4242]

First, thanks for having a forum like this!  I look forward to making this thing run like new, and it will be my first time tearing into a snowmobile motor.  My dad always had sleds around and I love riding them.  Now I love pulling my 5 yr old son around on a sled.  Can't get enough!

I have a 1979 Drifter 440 (date on the side plate reads 8/78.  Guessing this makes it a 79.  Wrong or right?).  Three years ago it ran amazingly well and was a lot of fun.  Two years ago I got one day of riding and then it lost power, almost to the point it wouldn't turn the belt when I picked up the rear end.  I parked it and didn't touch it.  This year same thing.  I got about an hour of riding where it ran amazing, and then back to loss of power.

1. Starts on 3rd-4th pull every time.  Even after sitting all year
2. First time it lost power this year I checked plugs.  One was wet, one was dry.  I checked for spark (pulled out plugs and inserted them into boots and pulled).  Both plugs showed spark.
3. I swapped plugs.  Cylinder 1's plug into cylinder 2 and visa versa.  It ran amazing for 30 mins. (thought that was odd and still don't know what to make of this) Then, lost power.  I quickly checked plugs and both were dry.
4.  I do smell gas when it bogs down, but when I check plugs they're dry. 

This is where I'm stuck.  I'm running out to buy new plugs today to try that.  I've read it could be crank seals or a clutch issue.  Neither of which I know how to test.  Does anything else come to mind?  I'm sure there are a handful of things, and I'm ready to try out anything while we still have snow here in Ohio!  FINALLY! 

Also, I'm in need of a windshield if anyone has one.

[MillerTime4242]

I should also mention I removed carb, tore it down and cleaned it.  Not 100% sure I did it right or that it's still not the culprit.  Also, when it is bogging down if I pull choke or pump fuel knob (whats correct term for this?) it instantly dies. 

[Ameritude]

To me it sounds a whole lot like compression, sounds like a cylinder has gone. If I were you. I would get my hands on a compression tester. Test both side when there cold, then when its hot and loses all power, test both cylinders again. Other guys on here will tell you what the compression is supposed to be (im not sure on the drifter), but the compression should be equal on both cylinders when its cold and then when its hot

[Ameritude]

They should be close to equal.

[MillerTime4242]

To me it sounds a whole lot like compression, sounds like a cylinder has gone. If I were you. I would get my hands on a compression tester. Test both side when there cold, then when its hot and loses all power, test both cylinders again. Other guys on here will tell you what the compression is supposed to be (im not sure on the drifter), but the compression should be equal on both cylinders when its cold and then when its hot

Once the tester is threaded in, I pull the pull start to get reading correct? Thanks.

[Ameritude]

Yep, pull it 2 or 3 times, or until the dial stops going up.

[Interceptor398]

Welcome to the site!!!

[MillerTime4242]

Welcome to the site!!!

Thanks!

[gixxer6]

Yep, pull it 2 or 3 times, or until the dial stops going up.

Also, hold the throttle wide open when you pull. 

[MillerTime4242]

I bought new plugs. But, before I installed them I started it up (two pulls) and took a lap. Half power from the get go.  Pulled it back into the yard. Installed new plugs and it took off like it’s supposed to. Plenty of power, however it only lasted a minute. Then back to crawling speed. 🤷🏻‍♂️

[Ameritude]

Were you able to compression test it yet? If so what were the numbers

[MillerTime4242]

Compression tested. Pulled 4 times with throttle wide open.

Clutch side 135
Other side 140

I also swapped the coil with one I know is working and no change. Still starts right up and barely has power to go. Exhaust removed, engine ran just the same. Air box removed, ran just the same.  When I prop up the back to get track off the ground, I can pulse the throttle and get the rpms high and track turning fast, but when I put it on the ground back to limping around.

[mswyka]

So reading this, compression is good.
The engine runs and has spark so ignition is ruled out.
The engine has made power intermittently

Plugging of the exhaust has been ruled out

Seems to point back to fuel delivery.

Have the carb been cleaned and jets replaced?

Are you sure that the fuel delivery system is clear from the tank to the engine?  I just had an experience where one of our Intruders would not spin up.  After checking everything i fished the pick-up tube out of the tank only to find the tip plugged with crud.

Are there cracks/leaks in the impulse line from the crankcase to the fuel pump?

Is the primer leaking?

Is the enrichener leaking?

[MillerTime4242]

If I fish out the puck up tube, does it reach all the way up to the fuel cap for inspection?

[Interceptor398]

You should be able to see it with a flashlight.