1977 Cyclone Help

[nascyclone]

Hello I'm new to the forum and snowmobiles in general. I used to ride two of my pap's snowmobiles, 77 and 78 Cyclone 440. They both quit running and haven't been touched in years. Well I decided to try fixing them. I've been working on the 77 cyclone first. I took out the gas tank, intake, and cleaned some of the carb. I ended up putting the floats in wrong (first time working on a carb) and flooded the engine. So I did some research. Fixed the carb, pinched the gas line, pulled the plugs and pulled until no more gas came out of the plug holes. Gas also came out of the exhaust. So I put new plugs in, fresh gas (new gas filter also), sprayed ether, held throttle wide open, and pulled. Tried to run (smoke came out exhaust). Pulled again, backfired out the exhaust. So i pulled the plugs and pulled until no more gas came out. Hooked the gas back up and gas starting coming out one of the carb vent holes??? I stopped the gas from going into it (gas tank is just sitting on chair next to snowmobile) then put it back. Stopped leaking. So I try again, backfires again. I'm at a loss of what to do next..I've read stuff online about crank seals, compression test, leak down test, etc. but I really have limited mechanical knowledge, but am always willing to learn. I just don't want to cause damage to the engine

Also: It has good spark

[harleysportster]

nascyclone,
Welcome aboard. What part of Pa are you from. There are a few of us who could be close to you.
Do you have any info as to why they stopped running so many years ago?
Carb flooding could be from a few things such as leaking needle/seat or the float height set to high. With the carb upside down and the bowl off, the float arms should be pallarel to the gasket surface. Set that then see if it still floods.
Click on this link for more info, be patient, it's a big file.
http://www.vintagesnow.com/John_Deere_f ... one_SM.pdf
The back-firing could be ignition related but you need to solve the flooding first.
Check back in the chat room in the evenings, a few guys are on sometimes.
Good luck and let us know how things are going.

[nascyclone]

I'm from State College (Central PA area). And okay thanks for the advice. I have the carburetor from the 78 with me and just went and cleaned it all up and adjusted it as that link says. I'll put that one on tomorrow and then re-tare apart the 77 carburetor and let you know how it goes.

Thanks

[nascyclone]

Okay so I went and tried again today. I found out the air/fuel screw was about three turns wrong so I fixed that, pulled plugs and pulled it to get any excess gas out. Sprayed some ether, tried staring it and it sounds like it wants to start, but won't. Backfires sometimes too. Pulled the plugs and their both wet, but the right one becomes very dark, like it's coated in oil. See pic. So I'm wondering if that one's not getting enough spark? I know both do have spark.

[JDT]

Sounds to me like your crankcase is full of fuel.

Extremely flooded!!

Shut off or disconnect the fuel, pull the plugs, turn off the ignition.
Buy a case of beer and invite four friends over for a rope pulling party.

After you have pulled it over a hundred times or so you may have expelled all the fuel from the engine.

And lay off the either.

And replace the crank seals. $10 well spent.
And when you replace them all the gas and oilly goo will run out of the engine.

[harleysportster]

I agree with Todd, it does sound like the crankcase is flooded. Does as he says pulling over the engine with the ignition off and plugs removed. Also, take off the exhaust pipe and see if it plugged up with a mouse nest. I would also buy an "in-line spark tester" and check for spark with the plugs screwed in. The plugs may not be firing under compression.

[JDT]

So true. Wet plugs won't spark.

[nascyclone]

Ok thanks for the advice. I'll pull the plugs, and pull my arm off. Already got one blister from pulling, but what's a couple more haha I'll update tomorrow.
Also never got into an engine. Replacing crank seals?..pull engine open, take out old seals, put new in?

Once again thank you for your help,
Nathan

[dap574]

Nathan, check pulse line on fuel pump for fuel leaking through. You can also leave the pulse line off while you pull the engine over to help blow fuel out of crank case. Be careful because it will spray out of the hose a long way! Dave

[400brian]

Ok thanks for the advice. I'll pull the plugs, and pull my arm off. Already got one blister from pulling, but what's a couple more haha I'll update tomorrow.
Also never got into an engine. Replacing crank seals?..pull engine open, take out old seals, put new in?

Once again thank you for your help,
Nathan

The seals can be replaced without opening up the engine. You will need a clutch puller, and a flywheel puller.

[harleysportster]

Ok thanks for the advice. I'll pull the plugs, and pull my arm off. Already got one blister from pulling, but what's a couple more haha I'll update tomorrow.
Also never got into an engine. Replacing crank seals?..pull engine open, take out old seals, put new in?

Once again thank you for your help,
Nathan

The seals can be replaced without opening up the engine. You will need a clutch puller, and a flywheel puller.

The service manual only explains replacing the seals on the PTO / Clutch side, follow the same guide lines for the MAG side but you will need to remove the flywheel and stator. Take note of the tiny index marks on the stator before you remove the timing ring and re-essemble in the same location.

[nascyclone]

Nathan, check pulse line on fuel pump for fuel leaking through. You can also leave the pulse line off while you pull the engine over to help blow fuel out of crank case. Be careful because it will spray out of the hose a long way! Dave

Alright I'll check that. I haven't had a chance to work on it, it rained the last five days here and the sled was sitting outside under a tarp, was able to make some room under a carport so I'll be able to try again.

[Viktory2k1]

Hello!
My first post here.
I have the exact same sled. got it a month ago and my dad bought it brand new in 77.
All I can say is if the crankcase is not airtight, your fuel pump wouldn't even work. If they are in fact bad, someone is pouring gas in carb,a lot.
I still have a few problems with mine but when I got it, I noticed the fan cover casting was half hanging off motor. So I pulled the motor and set it on garage floor with exhaust manifold resting on floor and about a quart of gas ran out.
This method may be eaiser for you instead of getting another blister. I will write more later with some really bad pics.
surprizingly, I got it running with the horrible gas that was in it which is old racing go-cart gas mixed to like 10:1 with oil. Leaves oil puddle on ground where "tail pipe" comes out.
P.s. I love this site!
Later(like 2 hours),
Vic

[JDT]

Twin cyclinder engines drive the fuel pmp from just one side.
Is the seal is bad on the oppsosite side it will still pump.

[Viktory2k1]

They usually leak at the same time or very soon. Good point
new to this site