540 XLV - won't go full throttle - Snowmobile Forum: Your #1 Snowmobile Forum

rescott1 · 12-28-2012, 09:31 AM

I recently got a '90 XLV, but it won't go full throttle - boggs and sputter. cleaned carb, changed gas, and plugs, same thing. Rode around for 15 minutes or so and the hotter it got ther worse it got.

Shut off, came back 10 minutes later and it wouldn't move (go over 3,000 rpm) just sputters, skipped, and backfired. Changed plugs again, same. I oddly decided to click the headlght to low beam and it fired up and took off. Still couldn't get full throttle though. While riding, changed the headlights back again, and it died right out. Same thing with the heated grips.

Now, the battery thats in it is old and dead, could that have something to do with this issue? Also, the brake light is funky, the red light for oil comes on when I squeeze (which I believe it's suppose to do), but rear light just dimes.

I think these things are related to why its running crappy and can't get full throttle, but no idea where to start. Any thoughts?

Yamaha440 · 12-28-2012, 09:41 AM

It should be able to run fine without the battery.

It sounds as though one of your coils has deteriorated. It is a common symptom if the coil is bad that it gets worse as the sled gets hotter. You can check them with a multimeter that measures resistance (ohms). After you test them, compare your result to the spec in the service manual. If it is out of spec, replace as needed.

rescott1 · 12-28-2012, 09:46 AM

Ok .. are they hard to replace? Expensive?

Yamaha440 · 12-28-2012, 09:55 AM

Coils can be anywhere from $20 to $100.

If they are on the stator, they can be a small challenge to replace. You would have to remove the flywheel to gain access to them, and after your done, you will have to time the sled again. If it is the external ignition coil (the coil the spark plug wires come out from) then it is a breeze, just plugs right in.

I don't have the ohm specs however, I hope someone else will chime in with those.

yamadad4 · 12-28-2012, 10:24 AM

check for shorts in your tailight wiring under the seat. almost sounds like it grounding out.

rescott1 · 12-28-2012, 10:36 AM

would the taillight grounding issue effect the rest of the issues mentioned or are they seperate issues?

yamadad4 · 12-28-2012, 10:57 AM

yes. your robbing power from the mag if you have and grounding. when you switched the high beam, that takes more power, same as when you pull the brake lever.

although not the root cause of your issues, its definately a contributing factor and free to test. you may toss a good battery in there just for fun.