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Snowmobile Repair/79 Yamaha Exciter 440


TERRY wrote at 2007-12-27 08:47:56
Sounds like fuel starvation. Drain all gas from tank,fish out gas filter and reverse pressure  clean with methyl alcohol and air pressure or install new if it seems hard to blow through with your mouth.Then take apart fuel pump and clean if nessessary,making sure the check valves are in good shape and diaphram as no crack or hole.While doing all this make sure all lines are clear including a leak free vaccume line (runs to engine base).Then take apart carb. making sure not to misplace any parts or strip any jet heads.Use spray carb. cleaner containing xylene and clean all jets and orifices,you may need to clear some passages with something such as oxy-acetylene tip cleaners(wire).If all as been done properly and problem still exist then check compression,low pessure will also give a similar problem.Maybe compression should be checked first but I would still do the fuel system cleaning givin that its been sitting for awhile.Sometimes a ring can stick but this is not as likely as poor fuel delivery.Also, make sure it's working on both cylinders,this is easily heard by someone experienced but you may have to pull of one plug wire at a time to check.A dead or weak cylinder can be caused by compression,spark, poor fuel delivery,or non-syncronized carburation(2 or more carbs).A 2 cylinder engine running on 1  cylinder will usually not have enough power to move very much, if at all.This is a new machine to you so inspect and expect everything and anything.

tim wrote at 2009-08-21 13:15:39
hi i had one of these sleds back when i was younger had the same problem ended up being mice made a nest in the exhaust system in the middle of the pipe had to cut it in half to get it out you can tell by taking the pipe off the motor and run it to see if it will make a difference.

mcguire wrote at 2014-11-07 06:18:20
I installed an inline filter before the fuel pump and have to use seafoam to keep carb clean on the off season months i also put oil in with fuel to help lube and cooling  

Snowmobile Repair

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I can answer most questions concerning snowmobile repair, including vintage and newer carbureted sleds.


I recently owned a 1978 Arctic Cat Lynx that I repainted and restored, a 1973 Ski Doo Olympique 440, a 1986 Arctic Cat El Tigre 6000, a 1990 Ski-Doo Formula Mach 1 and a 1973 Yamaha SL338C. I currently own a 1990 Arctic Cat Jag AFS Deluxe 440. I have rebuilt the carbs and fuel pumps, replaced tracks, slides, suspension,repaired chain cases,general body work, fixed the electrical on the sleds, and do just about anything possible with a sled. I used to work at a professional auto shop. I have accses to manuals and other helpful information, including good places for cheap parts. I am also a state park certified snowmobile operator

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