who here has messed with tuning VES springs?
- Thread starter Lorduss
- Start date
RMK 800/900's where CFI-4 (four injectors in a twin, two per cylinder) from 2005 through 2010. In 2011, poo introduced the CFI-2 for the 800, with just one injector per cylinder.
Four injectors had crossover transition issues on the big bores causing some of the runability issues these motors could have. Doo has the patent on twin cylinder injector crossover phasing from their SDIs (one phasing in while the other phases out). Poo couldn't phase, either on or off, causing a flat spot in the transition. Poo finally called it a day and went with a single injector per cylinder (earlier developed on the poo 600s). Transition problem gone.
G
geo
Well-known member
Interesting answers. I think comparing and stating your results from the past (pre solenoid activation) is why many are trying this on the present engine.
But is this comparing apples to apples? Was not the soleniod thrown in there to control this opening time so the 'putor thinks it knows the valve is open and adjusts accordingly?
Gonna be a long post here but I have wanted to play with this for a while. 'Cause I ain't stock lol and I had very favourable results in the past adjusting this on some modified engines in the past. Usually to the side of earlier opening from stock set-up.
Haven't been able to find answers in the last couple of years either lol.
DTR has shown CFM is higher with the valve closed. Late opening creates lean det condition (big CFI4 issue) because of the simple FI system with no Mass Air Sensor compensation. Play around in this spot may lead to lean-det condition eventually collapsing the skirts or worse from the piston crown overheating.
Poo has installed these springs for a while. They have the softer ones in stock too. If the solenoid dictates opening they could install the soft ones and still pass EPA stuff because of this feature. It's non-adjustable unless you have a Vipec or access to Poo over-write software.
One thing is for sure, the 'putor only knows when the solenoid opens. There is no electrical connection to the actual valve.
Why are the stiff ones in there? Are the softer ones an actual or part of a "fix Kit"?
So, theoretically lol, what peops are saying is the valve does not open when the solenoid does and putting in softer spring will make it open sooner. Hmmm.
My testing in the old days with Doos (pop out indicators on the valves in the spring without hood on twin pipe 670's) has shown me this function is only open or closed and no in between of any length of time. You could install any spring with any preload and change opening time but never create a multi step like the modern mechanical valves. You could go too early and get to too late but this was a simple system without the solenoid.
I'd like to know how people gathered this info and posted it because I've been trying to figure out how to watch the actual valve function (too old and blind to hang over the bars and watch nowadays lol).
To change something you need to first know what it is doing. I'd like to try an earlier valve opening on my Pro and I think I can do that mechanically adapting some aftermarket Doo RAVE stuff I still have kicking around. Thing is I don't want to do it just seat of pants way if I have an alternative.
Has someone figured out how to observe this in field? Or, are we still quessing? I can't afford a Vipec lol.
Some have said softer springs make the valves open earlier. How do you know that? My seat of pants feel I expected (more growl-shudder-pull in mid-range that I have experienced in the past when power is increased lol) didn't happen.
What does that mean,, nothin' lol.
My Pro showed some issues with rpm drop when stock (read it here many times too). Work the throttle in the deep and sooner or later the r's would drop. First thing I thought of was valves closing but not returning to open (cause it's happened before) because my clutches were cool.
Then I observed a temp correlation too.
So, I did TRS's Thermo mod and his recommendation of lighter springs all at once and have not had this issue since. I "believe" the valves stay open now and the temp has made a difference also. Was it more of one or the other??
But,, the one thing I didn't get rid of is a particular det spot (anyone in tune with their Pro will know what I mean) while running more compression. I actually needed to run 2 maps to get to play from top to bottom. Can't afford race fuel either lol.
My past experiences from similar case scenarios has showed me that opening the valves earlier has eliminated this "det spot" and allowed the continued use of a bit too much compression with the side benefit of more mid range when "carbed" correctly.
You can slow up the rpm increase but why create an RPM issue at another shift point?
Last year I chewed up the holes in the barrels and lowered compression while tightening squish and it was good and gone but I want more lol.
TRS. You have very specific recommendations and I've found them to be spot on. Can you shed some info on your findings and why you came to these conclusions?
Others that have posted or not any more info?
But is this comparing apples to apples? Was not the soleniod thrown in there to control this opening time so the 'putor thinks it knows the valve is open and adjusts accordingly?
Gonna be a long post here but I have wanted to play with this for a while. 'Cause I ain't stock lol and I had very favourable results in the past adjusting this on some modified engines in the past. Usually to the side of earlier opening from stock set-up.
Haven't been able to find answers in the last couple of years either lol.
DTR has shown CFM is higher with the valve closed. Late opening creates lean det condition (big CFI4 issue) because of the simple FI system with no Mass Air Sensor compensation. Play around in this spot may lead to lean-det condition eventually collapsing the skirts or worse from the piston crown overheating.
Poo has installed these springs for a while. They have the softer ones in stock too. If the solenoid dictates opening they could install the soft ones and still pass EPA stuff because of this feature. It's non-adjustable unless you have a Vipec or access to Poo over-write software.
One thing is for sure, the 'putor only knows when the solenoid opens. There is no electrical connection to the actual valve.
Why are the stiff ones in there? Are the softer ones an actual or part of a "fix Kit"?
So, theoretically lol, what peops are saying is the valve does not open when the solenoid does and putting in softer spring will make it open sooner. Hmmm.
My testing in the old days with Doos (pop out indicators on the valves in the spring without hood on twin pipe 670's) has shown me this function is only open or closed and no in between of any length of time. You could install any spring with any preload and change opening time but never create a multi step like the modern mechanical valves. You could go too early and get to too late but this was a simple system without the solenoid.
I'd like to know how people gathered this info and posted it because I've been trying to figure out how to watch the actual valve function (too old and blind to hang over the bars and watch nowadays lol).
To change something you need to first know what it is doing. I'd like to try an earlier valve opening on my Pro and I think I can do that mechanically adapting some aftermarket Doo RAVE stuff I still have kicking around. Thing is I don't want to do it just seat of pants way if I have an alternative.
Has someone figured out how to observe this in field? Or, are we still quessing? I can't afford a Vipec lol.
Some have said softer springs make the valves open earlier. How do you know that? My seat of pants feel I expected (more growl-shudder-pull in mid-range that I have experienced in the past when power is increased lol) didn't happen.
What does that mean,, nothin' lol.
My Pro showed some issues with rpm drop when stock (read it here many times too). Work the throttle in the deep and sooner or later the r's would drop. First thing I thought of was valves closing but not returning to open (cause it's happened before) because my clutches were cool.
Then I observed a temp correlation too.
So, I did TRS's Thermo mod and his recommendation of lighter springs all at once and have not had this issue since. I "believe" the valves stay open now and the temp has made a difference also. Was it more of one or the other??
But,, the one thing I didn't get rid of is a particular det spot (anyone in tune with their Pro will know what I mean) while running more compression. I actually needed to run 2 maps to get to play from top to bottom. Can't afford race fuel either lol.
My past experiences from similar case scenarios has showed me that opening the valves earlier has eliminated this "det spot" and allowed the continued use of a bit too much compression with the side benefit of more mid range when "carbed" correctly.
You can slow up the rpm increase but why create an RPM issue at another shift point?
Last year I chewed up the holes in the barrels and lowered compression while tightening squish and it was good and gone but I want more lol.
TRS. You have very specific recommendations and I've found them to be spot on. Can you shed some info on your findings and why you came to these conclusions?
Others that have posted or not any more info?
Thanks George. As you, I have been tuning for many years. I could go in depth but that would take a lot of ink.
I agree, if we could activate the valves around 6000 rpm things would be much better. But, I am pretty sure Yamaha owns the rights to that threshold.
That Det spot seems to come in around 6700 RPM, I truly believe this is Polaris' EPA sweet spot for emmisions and noise levels.
The ECU program activates the PRO 800 EVS from 7400-7600RPM. With the stock EV spring the valve opens slowly from 7600-7800. That is to close to peak torque on a cold or hot pipe. Once RPM drops below 7800 it drops the valve and the engine will not be able to recover without getting out of the throttle and back in. The green/white will let the EV open from 7500-7600RPM. Those of you that have installed them will notice a definate audible and pull at this RPM level when stepping through RPM levels.
I have been racing/tuning sleds since I was 10. Roundy round, cross country, grass drags, hillclimb. For years I kept my tuning secrets to myself, now I wish to share them with my brothers and sisters on Snowest.
Added note:
Prayers to the family and friends of the snowmobiler killed on Henderson today in Cooke
I agree, if we could activate the valves around 6000 rpm things would be much better. But, I am pretty sure Yamaha owns the rights to that threshold.
That Det spot seems to come in around 6700 RPM, I truly believe this is Polaris' EPA sweet spot for emmisions and noise levels.
The ECU program activates the PRO 800 EVS from 7400-7600RPM. With the stock EV spring the valve opens slowly from 7600-7800. That is to close to peak torque on a cold or hot pipe. Once RPM drops below 7800 it drops the valve and the engine will not be able to recover without getting out of the throttle and back in. The green/white will let the EV open from 7500-7600RPM. Those of you that have installed them will notice a definate audible and pull at this RPM level when stepping through RPM levels.
I have been racing/tuning sleds since I was 10. Roundy round, cross country, grass drags, hillclimb. For years I kept my tuning secrets to myself, now I wish to share them with my brothers and sisters on Snowest.
Added note:
Prayers to the family and friends of the snowmobiler killed on Henderson today in Cooke
Last edited:
Just a question for us that ride from sea level to 7000 plus feet; would we see an advantage as well? going to a lighter spring and moving the Exhaust Valves opening to a lower RPM? If so what spring, IYO, would be the best choice?
As I can ride from the house / garage which is at sea level and be at 6500-7000 in the span of 15 minutes. I'm looking for a setup that can handle that day in day out without monkeying with anything, if that is possible / practical?
Granted I'm in Alaska and our air density difference may com into play on the fueling side of things. FWIW
As I can ride from the house / garage which is at sea level and be at 6500-7000 in the span of 15 minutes. I'm looking for a setup that can handle that day in day out without monkeying with anything, if that is possible / practical?
Granted I'm in Alaska and our air density difference may com into play on the fueling side of things. FWIW
I would run the grn/wht if you ride above 5000' most of the time. I will test the grn/wht at 1400' during the Christmas Holiday in Wisconsin.(PRO 163)
G
gman086
Well-known member
I can definitely confirm the hotspot at 6,700-6,800 (especially with more compression) and the way around the solenoid control/Yamaha rights is to weld shut the vacuum hose nips on the valves (or pinch shut the hoses if you just want to experiment) = no more 'puter controlled valves, lol! Giving away ALL our secrets today... Happy Thanksgiving!
Have FUN!
G MAN
PS - Yes, the solenoid has some "limiting factors" which is why the green/white is about as light as you can get away with but all bets are off once you pinch shut those vacuum lines and then you can use however light of a spring you want!
Have FUN!
G MAN
PS - Yes, the solenoid has some "limiting factors" which is why the green/white is about as light as you can get away with but all bets are off once you pinch shut those vacuum lines and then you can use however light of a spring you want!
Last edited:
yes i see this alot in the vipec world. if we get the exhaust valve accuation down to even 6000. rpm becomes more consistant and motor likes it alot, det counts go down. so does pipe temps.
one other consistant in the data is the rpms. rpms will not back off then pick back up. when pulling through the 6000 rpm range.
the lower you get in elevation the more drastic it is.
one other consistant in the data is the rpms. rpms will not back off then pick back up. when pulling through the 6000 rpm range.
the lower you get in elevation the more drastic it is.
Have you eliminated the EVS and ran it solely on spring activation? With the Vipec you have a great tuning tool at hand. I would start with the EV vent lines plugged and experiment with EV springs.
Yes, that is the one I have found to perform the best to date.
Trs thanks for the helpful info, I really appreciate you sharing your findings on this. I ride from 8-12k would you still recommend green/ white or would you go lighter yet.
I run them to max elevation here, a little over 11,000'
Edit: I also run them in Alpine Big Horns and Sierra Madres WY, Daniels Summit Strawberry UT, Sonora Pass and Blue Lakes CA, and Penticton BC area.
Last edited:
Similar threads
