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does the 440 srx come with power valves. it was putting out around 98 hp in its best years, so if it didnt have power valves, and someone actually did put them in wouldnt it be putting out around 110-115. that would be insane for a 440. i dont know anything about power valves though so i could be wrong. i also dont think you could add them too a motor without totaly redoing the motor.
 

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no power valves on the 440 srx's (76-81). the first power valves came out in the late 80's from Bombardier.
to do that to a 440 srx motor would require extensive machine work to the cylinders.
 

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Actually Yamaha came up with the power valves quite some time before Bombardier (ski-doo) Ski-doo later seen what the power valves produced and made their own but the called them RAVE valves
However Ski-doo was the first to come out with a rotary valved two stroke back in the 80s
As far as the 440srx Snoeproe has it
There were not any power valves on a 440
 

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The first power valve came to dirtbikes and I believe it was CANAM was the first to do it. Rotary Valved in Ski Doo, I believe that came out in the 70s in a race version - I may be wrong. SRX440 was producing 80hp back in their time, which was alot then. WL.
 

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Rotary valve intake motors came out from Bombardier in 1973 Blizzard twin cylinder racers. the first production rotaty valve intake rotax motor was available in 1975 on the 245 TNT RV.
how did we end up discusing rotary valve rotax motors when the topic of discusion was power valves?
bombardier was the first to release power valves on a production snowmobile (RAVE) on the 1989 580 Mach1.
vintage yamaha srx 440's ('76-'81) did not have power valves. the '98-2002 yamaha 700 srx does have power valves.

'76 440 srx was 90hp stock
'77 440 srx was 96 hp stock
'78 440 srx was 83hp stock
'79 440 srx was 84hp stock
'80 440 srx was 82hp stock
 

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I know what year Rotary valves came out
Yamaha had power valves on their limited production 1975 model year
Had to ask Blain Morgan on the issue (Yamaha technical training support)
just to make sure
 

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whoops sorry 1975 is correct but it was for motorcycles thru Yamaha (limited models)
but as far as on snowmobiles yes Bombardier was the first sorry about that
a small misunderstanding on the Info I have received
 

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to answer the original question No powervalves will not create greater peak HP that what would be possible whithout them. in fact it could even hurt peak power. they serve only to broaden the powerband.
 
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