yamatard
New member
I am new to the snowmobiling world. I recently picked up a 2002 SX Viper for a good price. I know nothing about snowmobiles, as I am a car and heavy truck mechanic. What is the difference between the red,blue, and black cylinder heads? Thanks in advance
Devilin AblueDress!
New member
Well...obviously the color LOL! Red head = triple cylinder one piece head NON-powervalved motor. Blue is the SRX triple, has 3 individual heads with a coolant rail this motor has powervalves. Black is the Viper, triple cylinder one piece head, viper has power valves as well. SRX/Viper motors are very similar as some parts will interchange.
yamatard
New member
Thanks. Another question. What is the purpose of the power valves? What do they do?
Devilin AblueDress!
New member
They close at low rpm to make more back pressure on exhaust for low end GRUNT and then open up at higher rpm for top end GO! Much like running stock single exhaust on a car for economy when closed and a dual exhaust for more HP for performance when open.
yamatard
New member
Makes sense. Thanks for the info.
the powervalves alter the exh. port heigth, the higher the exh port is in a 2 stroke the more topend power it makes, the lower the port the more low end it makes. This is how yamaha was able to have the srx and viper be such a strong engine over a big rpm range, its changing the port timing of the exhaust port as the valve opens/closes.
Slick!
Slick!