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Lazy powervalves:

T
Oct 8, 2009
50
3
8
Through a lot of research I have read that the cause for the bog issue with the IQ sleds with cfi is lazy valves. Has anyone found a fix all for this situation or is the best option converting to carbs or getting rid of the sled. I bought an 09 RMK shift 600 155 last year and it only had 1800 miles on it. It is really nice clean sled but it has the intermittent bog issue at around 6500-6750 rpm. I have asked for help with the bog bit not received much input. So I figured try attacking this another way. Would upping compression help with the lazy valves to open them quicker? Any proven methods of fixing this issue. I really like the IQ chassis and have just returned to snowmobiling after a long hiatus do to a broken spine. I don't have enough money to just get rid of this one and get another sled. Please if you have proven fixes, please share them.
 
V

volcano buster

Well-known member
Nov 26, 2007
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Stayton Oregon
Have you pulled the valves, cleaned them, cleaned the port through the cylinder, checked that you have the correct spring and that the vent hoses are operable?

Once the valves are clean, run them back into the slots to make sure the slots are clean.

If clean and all other parts to them are in good shape there is no reason it should be lazy.

Do you know what your compression is on each hole?
 
T
Oct 8, 2009
50
3
8
Yes we have done all of that. We actually disconnected the hoses last year as several people on here and other sites said they run much better with the hoses disconnected and plugged. It did help some it seemed but did not fix the problem. As I had posted in my other thread about intermittent bogging issues, we have replaced the fuel filter, adjusted the throttle cable play. We did compression check last season also and it was very good compression. I can't recall the numbers now but I know we ruled that out. I put new powervalve springs in for my elevation, new gaskets, and coated the valves with my fire clean gun oil. I figured if it keeps carbon from building up in my guns it should help with the power valves. I have even installed 64 gram weights in the primary clutch as people have suggested. The bog according to doing research is actually caused by lazy power valves. I just have not read of a fix so far. It would seem logical if the valves are opening too slowly that a lighter weight spring would help. Guess I will try that.
 

TRS

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Cody, WY
We ran blue/white springs.
 

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TRS

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Cody, WY
Did you have an issue with the intermittent bog? If so did this fix your issue?

Not at our elevation, we needed lighter springs to get the valves to open. We ran the Blue/whites or Blue. They are the same value.
From ‘06 the 600’s never left the shop without the switch.
I’d check again. Make sure those EV ports are open in the cylinders. They can be trouble. Mechanics wire to clean them and a light through the ex. Port into the cylinder to guarantee they are clean.
Make sure the gasket isn’t leaking around the port, it definitely was/has been an issue. Next make sure the plastic hose barb is tight in the solenoid.
 
T
Oct 8, 2009
50
3
8
We ran a wire through and it did not hit any obstruction and came out pretty clean. I can certainly check again though more for the blown out gasket. I cleaned the valves very well last season and I use Amsoil and like I stated I used my Fire clean gun cleaner and lubricant on the valves to help keep carbon from sticking to them. That stuff works great in firearms so I figured what could it hurt to try it. I currently have the pink springs in it because they are for my elevation. However I will try just about anything at this point. Sometimes it just plain rips when the throttle is hit but most times it bogs then goes right in that 6500-6750 range. Thanks for your input. I am just about ready to pull the efi and install carbs.
 
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T
Oct 8, 2009
50
3
8
Well today I pulled it apart again. We found the mag side spring broken again. It has probably 200 miles on it. This is the same one that broke last season. I was wrong about what spring we put in it then. We put the stock Purple spring in. It is lighter than the blue/white springs. I ran a wire through all the port holes again, they were all open. There are two ports in the valve mounting block and just one from the cylinder. I re- cleaned everything and reassembled with new springs yet again. It did not change much if at all. Maybe a bit better but hard to say as it still occurs. I do not notice any smoke coming out of the solenoid hose though at all. This has me wondering if the solenoid is bad. How do you check it? Any other ideas?
 
T
Oct 8, 2009
50
3
8
Upon further research, I guess the solenoid does not open until about 3500 rpm. That would explain why I did not see any exhaust coming out the solenoid hose at idle. I forgot to mention I also checked the port the solenoid hoses hook up to for some sort of obstruction. They had some carbon but not plugged and not too much either. So am I just out of luck and am going to have to deal with this bog or anybody have other suggestions? I will try drilling out the valve mounting block and the cylinder like one post suggest to do. I know for sure though there is no obstruction and everything is clean yet the problem is still there.
 
T
Oct 8, 2009
50
3
8
Well I installed some blue springs today and it made it much worse. It had a major bog area and then would hit hard enough to pull the skis but would also backfire. I then put the purple springs back in. It does the same bog or stutter in the midrange right about half throttle. If you hammer it wide open on a take off it does not bog or stumble, if you get past half throttle and hammer down it also just goes no stumble or bog. It is right about half throttle. It feels like it just runs out of fuel for a split second then bang it goes. Does this help give any more ideas? Some have suggested it could be the clutches but I would think it would happen at the same area no matter if it was eased to half throttle or hammered to it if the clutches were the culprit. I still plan on drilling out the purge holes, but it makes we wonder if some red/white springs which are even lighter than the purples would take care of it. It seems the lighter the spring the better the symptoms.
 

XCaSSAULT

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Dec 9, 2016
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You said u plugged the ves hoses? If so then there wouldn’t be any exhaust out the solenoid hose, only when it’s hooked up. By my understanding the solenoid is open and always open till you reach somewhere in the 6,200-6,700 area then it shuts causing the valves to open. The solenoid isn’t variable just open then shut, and the valves are not variable just open or shut. It’s a really stupid system that none of the other manufacturer use and now polaris finally doesn’t use anymore with the axys motors.

I plugged mine when I first got my sled (800) because I hated the difference in power. Seemed like a 4stroke with valves shut and when then open it comes alive. Coming up to a snowbank and bliping the throttle would almost send me backwards. But plugging the hoses causes a lean spot in the midrange that gave me det lights when cruising. So u don’t wanna plug them unless u know what your doing with springs and adding fuel with a fuel controller.
 
T
Oct 8, 2009
50
3
8
Yeah we had plugged the hoses last season and it seemed to help some but not much so after doing all the research I have been doing we hooked them back up. I guess I forgot to mention that. The problem area is at half throttle. If you ease into the throttle and get into the midrange it just stumble ever so slightly. If you continue to accelerate it will make it past that area and then be very responsive. Same for just hammering it from a dead stop, it just rips. Problem is most riding we do is in the midrange right where the stumble is. I wish so had done more research before I bought it. I knew the 900 was a problem and had heard about the 800 being problematic but never heard any bad things about the 600 or the 700 until after I got mine and found it out researching my midrange bog or stumble. I never had an issue like this with carbs. I have a 2004 700 polaris XC/SP with over 10,000 hard miles on it and besides freshening up the clutches and replacing a water temp sensor and two helix because of the encapsulated bushing it has been trouble free.
 

XCaSSAULT

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Dec 9, 2016
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Same here. I got a 97-1/2 xc700 I’ve rode the snot outa for 18 years and although it’s needed work (mostly maintenance) it made me a polaris diehard. Time to get something new and these new ridder up style sleds are awesome and so easy/fun to ride, but polaris let down so many people with these shoty engineered machines. Seems like u can pretty much disregaurd all models from 05-15. The new axys motors seem to be doing well but we’ll see.

I’ve always heard the 600’s were bullet proof but that doesn’t seem to be your case.

I’ve got a lot of time and research into the mid-range stumble of the 800’s and the only way your gonna fix that is with a fuel controller and keeping your temps down. I’ve never heard of a mid-range stubble problem on a 600 (I’ve never looked into it neither). If someone more fimiliar with a 600cfi doesn’t chime in then u might have to go the fuel controller route.
 
T
Oct 8, 2009
50
3
8
I talked with Jim from dynotech research and he sent me a fuel commander. I mentioned that in my other thread, it did help some but caused back firing in the low range and flooded my plugs out also. He had me send it back as he said it should not have done that. He talked with the engineering guys at dynojet and they said I was out of luck with a fuel commander for a 2009 model. Their programming was for 2010 and up 600's. He did say I could most likely use a boondocker controller though. So I may end up doing that if the bigger purge holes do not solve my issue.
 

Mentzel

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Oct 10, 2009
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Ok start over.. The exhaust valves open by using pressure from the combustion chamber ports to inflate the exhaust valve bellows. The ECU sends signal to close solenoid valve on vent line at 6200+\- rpm. Once solenoid closes vent the bellows inflate and lift the exhaust valves. So from idle to 6200 rpm you should see the vent line puffing. Most drill a hole right by top shock mount and vent outside so it quits blowing oil in pan at low rpm. If you do not see puffing at low rpm, take everything apart inspect and clean as something is plugged.

Plugging the vent hoses makes no sense, and could cause low end bog, since valves need to be closed at low rpm.


Sent from my iPad using Tapatalk Pro
 

sledhed

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On the 800's there were issues with some of the exhaust valve gaskets and part numbers, just make sure that the exhaust passage is sealed so that it can't bleed off into one of the adjacent areas, it needs to seal to build pressure to open the valve. Even though the exhaust valve gasket looks right it may not be...

You can also get a bog from binding clutching. Not sure if that is covered in this thread yet or not...
 
T
Oct 8, 2009
50
3
8
I have taken it apart 3 times now and cleaned everything very well. I cannot find any obstruction. There is no smoke or any sign of exhaust coming from the solenoid tube. Is there a way to test it? I have put new gaskets on it and do not see any sign of them leaking anywhere. Primary clutch is all good to go, secondary clutch will get torn down soon. It actually behaved pretty well this past weekend. We rode 4 days in 4 1/2 - 5 feet of fresh powder and it never hiccuped once doing that. It did do it 3 times on the trails to and from our off trail riding areas though. I had to work hard to make it happen though. I think I am definitely heading in the right direction.
 

XCaSSAULT

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I copied this from another forum, basically it would be a good ideal to take all hoses off and make sure they’re clean and free-flowing, then make sure the valve opens and flows with 12vdc applied. Whether or not the ecu is telling the valve to open could be harder to test. Maybe a test light wired in and motor brought up to 7000plus;

The ECU on your engine, cannot regulate the opening and closing of the VES valves without all the components working properly, including the VES exhaust valve solenoid. Just removing the valve will not fix the VES system.

1. You may have an electrical fault in the wiring going to the solenoid.

2. It appears the exhaust valve solenoid has not been functioning properly for a while. Use some carb cleaner, spray it in the inlet and outlet nipples, let it sit, and then try to clean it out. The exhaust valve solenoid changes from open, at lower engine speed, to closed, at higher engine speed. Rig up some jumpers to something with a battery and test that the valve actually transitions between open and closed, when 12 volts D.C. is applied and disconnected. The electrical resistance across the exhaust valve solenoid, should be approximately 15 ohms. If the exhaust valve solenoid does not change between open and closed, you will have to replace it.

OPERATIONS on Pro-Ride models:

Solenoid energized ON, the vent is open, to release combustion chamber pressure behind the VES bellows.

Solenoid OFF (no electrical signal), the vent is closed. If enough combustion chamber pressure builds up, the bellows will lift the guillotine valve against spring pressure, and go into high speed exhaust port configuration.

There are three control situations for the solenoid:

At idle the solenoid is OFF (not energized), to avoid VES guillotine flutter. The vent is closed, but there is not enough combustion chamber pressure to allow the bellows to overcome spring pressure.

At engine speeds above idle, the ECU turns the solenoid ON, and the vent is open. VES guillotine stays in low speed position.

Based on a combination of inputs and rules involving higher engine rpm, the ECU turns the solenoid OFF, the vent closes, and combustion chamber pressure to the bellows overcomes spring pressure and raises the VES guillotine to high speed position.
 
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