Snowmobile World banner

1 - 10 of 10 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter #1
Hello all. Just got back from a great trip to northern MI (Gaylord area). Put on about 250 miles. Sled ran great except for fouling two plugs(BR9EYA's). This happened on two seperate occations. Once at about 125 miles into a days trip with temps at about 30 degrees, the other was after a cold start in the morning. Both times it was the PTO side cylinder. The plug was very carboned up and wet with fuel. Once a new plug was installed everything is fine. Since this is only happening to one cylinder I think I can rule out jetting. I checked my mains after a long full throttle run and ALL plugs were just about perfect. I think the problem with this cylinder occurs at idle or at a part throttle cruise. Any advise/suggustions would be appreciated. The sled has ~2,000 miles on it.
 Thanks,
Rob H
 

·
Registered
Joined
·
172 Posts
try messing with the idle circuit.     it sounds like the air idle screw is a little rich.   i cannot remember off the top of my head how to lean it out.   from what i can recall you turn the screw out to lean it out(lets more air through) only make small adjustments.   try it out, if it get worse turn it in.       btw it is the little screw on the side of the carb(the screw will probably be at an angle on the lower portion of the carb. it is the screw on the carb body, not the one by the throttle linkage. that is for setting the idle rpm). make sure you remember where it is now incase you have to put it back.

also you might try letting it idle for shorter periods of time, sleds heat up fast, get full of carbon, and as you can recall from personal experience foul plugs. EYA's are expensive to keep replacing too.
 

·
Registered
Joined
·
1,268 Posts
check the compression on the motor make sure it is close in all three jugs,  make sure carb is cleaned and needle is in the right place,    try switching the plug wires around.   good luck
 

·
Registered
Joined
·
40 Posts
Discussion Starter #5
I am going to check compression tonight. But when I checked it at the beginning of the season all three cylinders were ~150psi, and I have had this plug fouling problem since then. I will check carbs, but have had them off and cleaned them and things didn't change.  The only thing I didn't do was check the choke plungers. I am hoping the one for my pto cylinder carb is leaking. I did not know you could swap plug wires arround.
 

·
Registered
Joined
·
185 Posts
Rob,

If you look at a previous post about someone getting the plug wires mixed up, its fine, they all fire at the same time, its only the one piston that fires when its at the proper position.  The only company that has an ignition system that fires according to each cylinder is Yamaha, and I don't even know if its out, I heard they were working on one a while back (1 year).  So, the answer to  your question is yes, you can swap the wires around, but I also agree to check  your choke on that one carb first...

just my $.02

Steve
 

·
Registered
Joined
·
40 Posts
Discussion Starter #8
Ok, checked the carbs last night. Choke plunger looked ok, and seemed to be seating. Needle clip position is in #2 on all carbs. Fuel screws (larger white thumb screws) are all at 1.5 turns out. However, the small air screws located at the air horn opening were all at 1.5 turnes execpt for the pto carb which was at 2 turnes. I corrected it to 1.5 turnes like the others. But this doesn't make sense. I thought the the more turns our the air screws are means leaner. but this wasn't the case. I hope I am not mixing the two (fuel and air) screws up. Please let me know.
 

·
Registered
Joined
·
172 Posts
It might be that way too      i wasn't sure when I posted that reply.     the screw might meter the fuel flow, so turning it in will lean it out(flow less fuel)       can't remember it is was metering fuel or air.     if turning it in helps then who cares   as long as it worked :)

Also, did you try the sled out now that you made the changed to the screw?
 

·
Registered
Joined
·
40 Posts
Discussion Starter #10
In regards to the fuel and or air screws.  On flat slide carbs the idle fuel screws are the larger ones with a white thumb wheel attached.  These adjust like this: turn out = more fuel, turn in = less fuel.  The small screws on the side of the air horn are the idle air screws. They adjest like this: turn out = more air, turn in  = less air.  My stock settings for both are 1.5 turns out. This is where they are right now. Unfortunetly I don't think I will be riding any more.  This summer I am planning some mods like pipes, cold air box, and v-force reads.  These items will no doubt require carb changes, so it is useless for me to mess with this anymore now.  Thanks for the help.
 
1 - 10 of 10 Posts
Top