[stenzo]

A buddy and I were out on Sunday, and then a problem with his sled started. Performance loss and lots of smoke, in taking it easy riding it back towards an access point he literally burned off a full tank of gas within 30km. Any ideas what could be wrong? Where we should start looking?

 

[rider_quad]

A buddy and I were out on Sunday, and then a problem with his sled started. Performance loss and lots of smoke, in taking it easy riding it back towards an access point he literally burned off a full tank of gas within 30km. Any ideas what could be wrong? Where we should start looking?[/b]

You should take the carbs apart and give them a good cleaning paying special attention to the needle and seat make sure they are not wore out. this happened to my friends 700 vmax xtc it had the same symptoms you describe.

 

[AL vmax4]

bad plug?

 

[stenzo]

bad plug?[/b]

That was the first thing we changed all plugs when it started but no difference.

 

[CottageRob]

That was the first thing we changed all plugs when it started but no difference.[/b]

It may be the carbs freezing up. Yamaha had that problem when they first redesigned their sleds and that’s why the added the heated carbs. It only happens on extremely cold days. Did you do a compression test?

 

[8vo fan]

There is also a possibility the fuel pump diaphagm cracked. I would warm it up(heated garage), Check compression. If compression checks out then start it and see if it runs ok. If it does then you know it was carb icing.

 

[sledman92]

Sounds to me like a frozen or stuck choke, I would check that before ripping the carbs off..........

 

[rx1mtnsaskguy]

Give the caps a check too. Where any of the plugs more wet than the others?

 

[stenzo]

Give the caps a check too. Where any of the plugs more wet than the others?[/b]

Checked all the wires and plugs last night, they all appear dry and have a good spark. Turns out that the valve for heated carbs was in the off position... having a tuff time trying to get the sled into a heated area to thaw, it's too cold out in a uninsulated garage to warm up effectively. The choke is frozen and the carb heater was off so the problem is leading us to the carbs being iced up.

Does anyone know why there would be an on/off for carb heaters? Performance at different temp ranges? When should it be turned off?

 

[Bone Daddy]

Sounds to me like a frozen or stuck choke, I would check that before ripping the carbs off..........[/b]

I agree.

 

[stenzo]

I agree.[/b]

After thawing with heaters, it appears the problem has cleared up...

Thank you for your comments.