Plugged Exhaust Valves?

owenbstory · Oct 13, 2009

I read this in another post for a 700 dragon. I am wondering why polaris put those hoses on there in the first place. Is this a bad idea? What are the effects? Good and bad.

Plug the exhaust purge hoses coming off the exhaust valves, all they do is hold heat in the motor and cause you to lose performance by delaying the opening of the exhaust valves, so now it will be like the exhaust valve set-ups on the older 2001-2005 models.

Vfrtrader · Oct 13, 2009

it's because of emissions (damn EPA) the hoses go to that little canister, at 5800 it closes and the normal pressure from the engine opens the valves, like the older sleds. If the canister gets too much oil and carbon, it can stick open thus no pressure, thus valves don't open. It happened on my 900. you can cap off the hoses but the valves might open to early and create a mid-range bogg. you would have to change the spring. Don't unhook the wires to the canister. It will sent a code the computer.

Kraven · Oct 14, 2009

Vfrtrader said:
it's because of emissions (damn EPA) the hoses go to that little canister, at 5800 it closes and the normal pressure from the engine opens the valves, like the older sleds. If the canister gets too much oil and carbon, it can stick open thus no pressure, thus valves don't open. It happened on my 900. you can cap off the hoses but the valves might open to early and create a mid-range bogg. you would have to change the spring. Don't unhook the wires to the canister. It will sent a code the computer.

X2^^^^^^^^^^^

That was me that posted that. Just use the exhaust springs from an older 800

You could also try installing a simple 1/4" shut-off (into the back side of the P.T.O. head) into the cooling line that heats the throttle bodies. Running hot antifreeze heating up the intake charge isn't neccesary unless you're in real snowy,dusty conditions, I.M.O.

BTW, the coolant shut-off comes stock on 2007 800 Ski-Doo's and others

Hope this helps.

owenbstory · Oct 14, 2009

More

Supposing that one would cap off these hoses, leave the wires hooked up to the canister to keep the ecu happy, and install what i'm assuming are older 800 springs that are stiffer, what are we gaining? Other than avioding the eventual plugging up of the canister that (to me so far) dose the same job? Thanks for all the input guys i'm trying to get my head wrapped around all this new to me efi stuff.

Kraven · Oct 14, 2009

owenbstory said:
Supposing that one would cap off these hoses, leave the wires hooked up to the canister to keep the ecu happy, and install what i'm assuming are older 800 springs that are stiffer, what are we gaining? Other than avioding the eventual plugging up of the canister that (to me so far) dose the same job? Thanks for all the input guys i'm trying to get my head wrapped around all this new to me efi stuff.

I prefer to plug the exhaust valves individually, if you plug the "purge" hose coming off the "canister/solenoid" the exhaust valves will still be tied to each other.

owenbstory · Oct 14, 2009

Still Wondering

What is the advatage of doing this?

Kraven · Oct 14, 2009

owenbstory said:
What is the advatage of doing this?

I'm assuming you're asking why plug them individually, and if so, the reason is that so that pressure from one exhaust valve doesn't impact the other cylinder.

Guys have tried them both ways says it doesn't matter (and maybe it doesn't) that's why I mentioned I perfer to cap/plug them individually, and and since there's no downside to it, why not I.M.H.O.??

owenbstory · Oct 14, 2009

Why plug them at all

More specifically Why are we plugging them in the first place? Is it going to make my sled run differently? Better? More top end? less bottom end torque? What is the function of that little oil soaked bugger and what is he doing to me? LOL!:beer;

owenbstory · Oct 14, 2009

Also

If as stated above and you unhooked the canister from the wire harness the ecu would know it. So if it's opening at 5800 rpm wouldn't the computer know that it is opened or closed? And if so dosen't the fuel and/or spark change accordingly? Maybe this system is not that advanced? I don't want to go plugging these off and get a lean WOT condition. And I'm done early this season.

Kraven · Oct 14, 2009

owenbstory said:
If as stated above and you unhooked the canister from the wire harness the ecu would know it. So if it's opening at 5800 rpm wouldn't the computer know that it is opened or closed? And if so dosen't the fuel and/or spark change accordingly? Maybe this system is not that advanced? I don't want to go plugging these off and get a lean WOT condition. And I'm done early this season.

I think you may have some misconceptions here.

All the solenoid does is delay the opening of the exhaust valves. Plug the hoses and your acceleration will improve, top end remains unchanged as the valves would already be fully open either way, thus NO chance @ LEAN burndown @ W.O.T. since exhaust valves are fully open either way.

If you want to convince yourself this works, bring your sled out and run it along side a "test mule" sled. Stop, take some little mini-vice grips, clamp off the hoses, race again and experience the results for yourself.

It works, plain and simple.:face-icon-small-hap

Look back at the 2001-2004 V.E.S. sleds, no purge hoses. As VFRtrader stated in post#2 it's there for emmisions reasons, NOT for performance improvement.

ghostwhite · Oct 15, 2009

can we get a part number? assuming its the same for the 900s

owenbstory · Oct 15, 2009

Ok

I'm following you now. So did you have to get the early 800 ves springs for yours or not? In your experiance what is to soon to open rpm wise? I've experianced the low end bog on my (no longer with us) M1000. And would rather not go down that road. Thanks for all the info. I really appreciate it.

corpeleven · Oct 15, 2009

Interesting

I've got an 07 600 HO carb.

My question is: If I were to try this, I'd want to get the exhaust springs from an 05 or older 600, not an 800 right?

Kraven · Oct 15, 2009

corpeleven said:
I've got an 07 600 HO carb.

My question is: If I were to try this, I'd want to get the exhaust springs from an 05 or older 600, not an 800 right?

Correct on the bold, on the 600

Also get the exhaust spring for the elevation you're running at, usually higher elevations have lighter springs than lower elevation set-ups.

I usually ride @ 1200' (U.P. Michigan) when I brought my 2002 800 EDGE-X to Yellowstone, I changed the exhaust valve springs to a lighter tension (STOCK POLARIS SPRING) and it was definitely YELLOW but I don't have the part #

Sorry I don't have a part # guys, perhaps mountainhorse can chime in, I thought he posted a list of exhaust springs available some time ago????????

Hope this info helps.

SD Coyote · Oct 15, 2009

04 Deep snow manual 04 600 h alt green/white #7041786-03 04 700 h alt orange #7041704-02 04 800 h alt pink #7041704-03

silverfox · Oct 19, 2009

plugged vents

If you plug the vent coming out of the exhaust valve wouldn't that NOT allow the valve to open?

SnoKing · Oct 19, 2009

silverfox said:
If you plug the vent coming out of the exhaust valve wouldn't that NOT allow the valve to open?

The vent is UNDER the diaphragm, where the exhaust pressure builds to open the valve The "canister" is a solenoid valve which is being held open to allow exhaust to escape until 5800 RPM's are reached and then it closes to allow full opening.

If the solenoid hangs up or there is a leak in the hose system then the valves may not open in that rpm range and you could have some bogging.

I have theorized that leaving both manifolded together (instead of plugging individually) could possibly balance the operation of the valves somewhat similiar to what a boost bottle did for the carbs, but I'm not sure.

A quick test is to plug the discharge hose that comes off the solenoid and just goes into the belly pan on the Polaris (vented to atmosphere ) and put a 1/4- 20 bolt that has a solid shank for a plug (I used an 1-1/2 long)

towngrunt · Oct 20, 2009

This is a good thread. I have an 08 and a 09 Dragon 8 and will try this on both of them. I have had continual RPM issues with my 08 and was wondering if this could have contributed to this.

Daggerboat · Oct 21, 2009

Reason for delaying valves opening

If polaris delays valve opening RPM for emissions , can we assume that disableing this may help prevent the lean midrange....Or is this a fine tuning of the torque curve for these new motors....I just installed a digatron to help with dialing in my '07 600 this winter but has anybody with EGT's experimented with plugging this vent....Also , for the 600 carb the RPM is delayed till 6700 or 7200 depending on throttle position

ghostwhite · Oct 21, 2009

I am wanting to do this on my 05 900 rmk and understand the effects but will an older 800 spring work on my 900?

Plugged Exhaust Valves?

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Similar threads