JD Cyclone - Snowmobile Forum: Your #1 Snowmobile Forum

Bulldog · 10-04-2005, 12:05 AM

I picked up a 78 JD Cyclone 340 for $300 at Haydays last month and am trying to get it running now. The sled is in great shape and will fire on full choke and sputter for a few seconds but I can not keep it running. I've had the carb out and apart, got it all cleaned up an also put fresh gas in the tank. Plugs look good. Anyone have any ideas?

**smallengineguy** · 10-04-2005, 07:14 AM

Do a compression test to be sure it is where it should be. It should have 120 lbs per side for good running and should be within 10% of each other. You can get a compression tester at any parts store.

**RJ Gleason** · 10-04-2005, 06:32 PM

you could also have a pin hole in the diaphram of the fuel pump. If you did not already replace it, see if you are getting any fuel up the lines.

Bulldog · 11-07-2005, 11:16 PM

I finally got back to the JD.....Compression 90 lbs on one side, 20 on the other, Guess it's time to start pulling it apart

**smallengineguy** · 11-08-2005, 06:20 AM

Ouch...