[greenstang02]

Hi! Bad english but here i go. I own a panther 370 fan cooled twin, single carb 2003 since 2013. Sled always run fine but always been really noisy like you have the exhaust pipe in the face. Considered many time to wear ear plugs, its a strange engine sound like an harmanonic coming from uner the hood or something.

But today i sledded in mountains and the huge sound dissapeared for 20-25 minutes. I was afraid something gone wrong but everything was fine, engine very smooth, maybe a little more power (easy to notice on a 36 hp sled). Get off the mountains, no strange sound, so altitude no really an issue, shut off engine, take a 5 min break and the restarded it and the awful noise was back again until home.

Stock carb, stock jets, float height is within specs, but plugs always been on the black side a little but leave it that way to be safe. Maybe they are designed like that wondering if the 570 fan user has the same issues.

 

[kccats]

Welcome
Do you see any exhaust smoke under the hood?
Could there be an issue with the can?

 

[Arctic Cat ZL440]

Sounds like a muffler issue.

 

[greenstang02]

No smoke, exhaust is like new. Maybe sounds coming from air box i seriously dont know. One thing for sure, i had nothing in the mountains, maybe the sled was happy with different air/fuel mixture i dont know. I consider playing with timing maybe.

 

[kccats]

Not likely timing, can't move.
Most likely in the carbs, if the elevation helped you may be too lean at sea level?

 

[greenstang02]

Thanks! Plugs already grey/black. But i will consider what you say will play with jet needle to richen it. Always drive it at part throttle, only slight improvement at wot as if engine cant take too much air/fuel. Didnt know it has fixed timing.