Another little trick for the 900

BIGGDAWG · Jan 16, 2011

jsledder said:
Umm.... It's past "next week" :lol:

I'm going to try the plug method first. I can't tell you how nice it is to have all you testers out there playing with things and sharing your findings for the rest of us. Imagine how many dead 900's there would be.

sorry forgot to post up, my sled is running great. i think this mod is great for all sleds not just the 9's.

mine is holding r's and not loosing power after wot for long pulls. very responsive too but that could be my bigbore too. lol

i am running stock springs and so is my brother with his 900 both are running good no bogs.

pwdrking · Jan 18, 2011

You all may think I'm crazy, I was going to do this mod but after some reserach I don't think the 900's even need exhaust valves! So what I did was plug off the solenoid and zip tied the valves all the way open, so they stay open all the time. I was hesitant at first, but I took it out and holy crap! This thing came out of its shell and ran like crazy! It sounds like a mod sled and runs like a mod sled whoohoo! The only down side I could even find was the fuel economy. Im willing to give that up if my sled performs like this.

Z-Man · Jan 18, 2011

pwdrking said:
You all may think I'm crazy, I was going to do this mod but after some reserach I don't think the 900's even need exhaust valves! So what I did was plug off the solenoid and zip tied the valves all the way open, so they stay open all the time. I was hesitant at first, but I took it out and holy crap! This thing came out of its shell and ran like crazy! It sounds like a mod sled and runs like a mod sled whoohoo! The only down side I could even find was the fuel economy. Im willing to give that up if my sled performs like this.

Interesting, Mine already sounds like a Mod sled.

pwdrking · Jan 18, 2011

Im just saying it changed the way it sounded from what it was before

stickshift69 · Feb 14, 2011

TTT,,, wondering how this mod works without the seal?

Danbot · Feb 14, 2011

stickshift69 said:
TTT,,, wondering how this mod works without the seal?

Perfectly. I never did put a seal in.... just over-sized the pressure feed holes. My hoses were already plugged before this mod, but the valves seem to open sooner and more suddenly, very good "seat of the pants" feel from this mod for sure. Oh and stil on the stock springs riding between 3500 - 8000 feet.

sno_mo_racer · Mar 18, 2011

Well I have my engine out to replace the mounts, cleaned the valves also and was looking at the compression holes on the cylinder and the valve base. The compression holes didn't line up. I didn't have camera with me last night so I found some pics from other posts here to go by.

In the first pic you can see the hole on the cylinder is on the right side same as mine, and on the 2nd pic on the valve base the hole is on the left side so they do not connect so I drilled another hole on the base like in the pic but on the right side so the pressure holes can connect.

Have no idea what difference it made as just waiting on my engine mounts to replace before the engine can be put back in.

But as I see this may be same as on all 900's? so why the trouble of drilling that hole on the base if it wasn't connected to the cylinder pressure in the first place? As I noticed it I made a long screw thin enough to go through and put it through the hole on the cylinder and it was pretty plugged up from not getting any pressure through it. so cleaned them out and put back together after got it done.

EDIT-forgot to mention that the gaskets I had on only had the one hole which was on the hole in the cylinder can't remember what brand gaskets they were(ordered from royal distributing) and the ones I got from Polaris had two holes on both left and right for in pic one.

Danbot · Mar 18, 2011

Your right, the holes are on opposite sides, but in this pic you can see that there is a cavity in the underside of the valve base that allows the pressure feed to pass. The oem polaris gaskets are as you describe, but because of the cavity, the pressure goes through.

I am interested in hearing your results since (depending on the size of hole you drilled) you likely have over doubled the potential pressure feed in the valve body. The cylinder hole is surely now the restrictive point in the system.

sno_mo_racer · Mar 18, 2011

Danbot said:
Your right, the holes are on opposite sides, but in this pic you can see that there is a cavity in the underside of the valve base that allows the pressure feed to pass. The oem polaris gaskets are as you describe, but because of the cavity, the pressure goes through.

I am interested in hearing your results since (depending on the size of hole you drilled) you likely have over doubled the potential pressure feed in the valve body. The cylinder hole is surely now the restrictive point in the system.

Yes after I made the post I remembered about the cavity on the base and realized I now have 2 holes drilled so covered one up with some JB weld. Hopefully that stuff will work on the base for the little hole. I drilled the new hole 3/32" and covered the other so that the holes can be on same side. Also with the other exhaust valve gaskets which only had one hole the cylinder hole was covered so had it on wrong way. from now on will only get the polaris ones or make sure I have them on the right way.

Z-Man · Feb 9, 2012

OK, I had to do a little searching to find this but I have a question for the guys who did this. Is anyone having problems caused by this, specifically blowing holes in the exhaust bellows?

I am working on my 975 turbo right now and had both exhaust valves get holes blown in them. At first I thought it was caused by bolt coming loose but on closer inspection this mod had been done and where the new holes are in the base is exactly where 1/4 holes were blown in the bellows. It looks to me like when turbo is building pressure it blows right through the bellows.

Danbot · Feb 10, 2012

Z-Man said:
OK, I had to do a little searching to find this but I have a question for the guys who did this. Is anyone having problems caused by this, specifically blowing holes in the exhaust bellows?

I am working on my 975 turbo right now and had both exhaust valves get holes blown in them. At first I thought it was caused by bolt coming loose but on closer inspection this mod had been done and where the new holes are in the base is exactly where 1/4 holes were blown in the bellows. It looks to me like when turbo is building pressure it blows right through the bellows.

Lot's of hard miles, and no problems with mine. Boost might be too much?

Z-Man · Feb 10, 2012

Kind of what i am thinking

Danbot · Feb 10, 2012

There's gotta be a way to diffuse the pressure feed to that it's not such a concentrated rubber piercing stream.

I have 3 idea's right away:

1- supersize the vertical hole in the valve body so it does not spray in such a small stream

2- countersink the top of the same hole, this might diffuse the stream

3- mount a small tin baffle plate over the same hole to redirect the stream to the side

I'll dig up my spare valve bodies tonight and take a look around.

Z-Man · Feb 10, 2012

Think I am just going to take the valves off one of the other 900's and then put the ones of the turbo on the non-turbo.

Danbot · Feb 10, 2012

Thats a HUGE tear! I have only ever had little pin holes. Nice gloves Dr Z

Newfusion900 · Jun 23, 2012

Anyone ever figure out what the correct seal is? Is it the mag side crank seal? Thinking of doing this mod as long as it does not cause any other problems. If I got it right you just drill a hole straight down to where the hoses go on and one at an angle to line up with the hole inside the base? Thinking about starting to do some hill climb drag races so this may be beneficial. Thanks in advance.

Z-Man · Jun 23, 2012

I had to replace the valves on my turbo because it would blow holes through the bellows constantly. I think I would try just getting some lighter springs from SLP first.

Newfusion900 · Jun 23, 2012

Z-Man, Do you think using lighter springs will give you the same effect with this mod running without the hoses plugged? What SLP springs do you have in mind, I read in the previous posts about the white ones. Do you think these will work properly. Thanks

Z-Man · Jun 23, 2012

Only thing it did for me was blow the bellows out on every ride.

http://www.startinglineproducts.com/catalog.cfm?pageID=detail&catalogID=3&catID=18&productID=155

Newfusion900 · Jun 23, 2012

Ok, thanks. I was going to replace the exhaust valve springs anyway so I will order some from SLP. I think I will go with the white to try them out.

Another little trick for the 900

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