1986 Enticer - Running Rough - Help Please - Snowmobile World : Your #1 Snowmobile Forum
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post #1 of 2 (permalink) Old 01-04-2016, 05:55 AM Thread Starter
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1986 Enticer - Running Rough - Help Please

I bought this old 340 for my son and he's just begun his 3rd season with it. I took a buddy's advice when looking for an old sled to find a nice clean Yamaha 340. It's been great and has provided hours of enjoyment. Up until now the only issue we ever had with it was the coil wire detaching from the coil body. I was able to carve back the plastic/rubber far enough to solder it back on, taped it up for safety, and never looked back.

This season it fired right up and was working great until just recently. It still starts up fine and after it's warmed up for a minute or so, we can do a few rips with it but then it loses power, sputters, coughs, pops, misses, and just won't rev up any more. You have to kinda feather it back to the garage.

- Fresh fuel
- Fuel pump working
- no change with choke on
- I've swapped plugs, no change
- I've swapped coils, no change
- I've cleaned the carb (it was fine), no change
- compression when warm 100/105 psi
- sprayed brake cleaner on PTO side of crank and intake gaskets, no change

I've attached a picture of the plugs and they are light brownish, but maybe just a touch lean? Also the oil pump setting is threaded outwards from the carb bracket to the max (for max oiling). And, we also put a blurp of oil into the gas tank for safety.

I have another '81 Enticer here and thought I could swap CDI's, but the wiring connections are not compatible.

Am I missing anything else????
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post #2 of 2 (permalink) Old 01-04-2016, 10:07 AM
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Join Date: Nov 2002
Location: Oregon
Posts: 1,352
Plugs look good, maybe a tiny bit lean, the jetting would be marginal if the weather turned colder. You have tried all the stuff I would have tried, except for unscrewing the plug cap and snipping 1/4" of wire off the wire, then screwing the cap back in. Sometimes the connection at the wire to the plug gets bad, and fresh wire may help.

If the compression gauge is accurate, 100 is marginal for a good running engine. It may be time for some new rings/pistons. But I would be going like you have; searching for an electrical issue that is worse when the engine is warm.

Good luck.. hunting down these kind of gremlins can be an exercise in frustration!!

2007 RMK 700, 2008 RMK 600, 1995 AC Prowler 2-up, 1980? AC Cheetah
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