Would be great but we can’t even trust 91-92 octane in Wi/mi most of the time !

 

I imagine BCM is also reprogramming the ECU and not just bolting on a different head?

 

That's correct sir..

 

I saw the numbers too, I can’t believe the power that thing is putting out on race gas. There’s not a 4 stroke out there that’ll touch the Boost.

 

I don’t have a boost or 4S turbo, but man I am praying some of you guys gets snow soon so I can see what the boost has compared to the winders and t cats! I am extremely anxious to see how these sleds compare heads up.

 

I tried to get a boost on the first day of Snow Check but dealers around me were sold out. So thinking about a BCM 900 for my 22 XCR instead ?

 

I would just be happy with what you have and get a stock 9R next year.

 

In response to T HILLRIDER....

BCM made a very limited amout of 900's this Summer for the upcoming winter season. They sold out pretty quickly. If you want one for this year I'd get on his next list of special orders.

While I do prefer a BCM 900 over a Carl's 900 I do have a Carl's 900 Kit for sale that has only 260 miles on it. Carl's recommends the Diamond S can with their 900 kit. I have one of those to sell too.
I installed the kit at the end of last year in March as trails were deteriorating quickly. I ran it breaking it in perfectly on nice northern trails on two back to back days in one weekend.
$2,600 Cash or $2,000 w/ your 850 Cylinders and Exhaust Valve assembly. (( Diamond S Can not included in that price. ))

If anybody is interested, please just PM me with your questions.

 

Well that’s an option. But a good aftermarket 900 or tweaked 850 will hand a stock 900r it’s ass.

 

After looking at and measuring the 900r’s cylinder ports I think it has potential… I’m only in disagreement with the stinger size of the 900r pipe but that’s an easy fix.

 

I haven’t had a R in my hand. But I know just going from 840 to 900 isn’t that big of a gain by itself when just CC a and port matched. I think it’s like 5-6. In the bore. If 850 is 168/170 I would guess a Polaris 9r to be 174-176. In stock form. Which we know a bit of 850 tweaking can surpass that. I don’t think its. (9r) is gonna be bad. I just think for the price. Of going to a new sled just for the 9r. Less money might be better spent.

 

The 900r is much more then just a port match. The porting is substantially different and I would put it up against any aftermarket single pipe 900 all else being equal.

 

I forget the full hype of the 9R but beyond just the CNC porting I believe it has a 650 crank and lighter flywheel as well as other things. Those with reviews say it spools up much quicker. So, when it comes to tweaking the current 850's and 900's my thought is to buy the 9R and tweak that with all the same tricks that are working being done to the current aftermarket 900's. Then where will the comparison land? I'm not just thinking of what happens in a straight line with a 1" track and a bazillion studs but what it will be with a much different set up.

 

Spooling up fast is great for mountain riding but all those lightweight parts dont usually do real well on a bunch of mile long pulls.

 

I’ll take the stock version 9R with a little clutching. For the trail and buddy racing, not worth modding any more IMO. I’ll take warranty. Don’t need a turbo, just want it simple, just more things to go wrong. And, the 9R isn’t that far off from the turbo at sea level.

 

My exhaust port didn’t come like that, that’s for sure . But it looks a lot like that now .

 

It sounds like that was part of the recipe for getting the 900’s to make hp.
That with a much larger y pipe. The exhaust outlet on the 900r is 49.5mm across.

 

The port timing is more of what I’m referring to..

 

I didn’t have cylinder installed on an engine nor did I have 900r pistons which are a bit different, ring location is changed, so no degrees were taken. I measured all the port sizes, heights, widths, angles. Which is good enough for me…

 

Coming from automotive light weight in the rotating assembly is good for everything. especially high rpm and long pulls. there is no downside to it as long as the materials are strong enough. Lighter weight is more stable and easier to control as speeds increase.

why would it be a bad thing on a sled for the crank or flywheel to be light? guess im not sure why...other than if they arent strong enough. I can see no downside

 

Apples to oranges.I dont see 8000 rpm 2strokes that hold up in the auto industry.Mazda tried but it didnt go so well.
A lightweight rotating assembly is far more prone to issues when its run hard.Just as an example the soo sleds and other oval endurance sleds run heavy rotating assemblies because they have to go wide open all day.
The lightweight stuff is fine for snox and the mountains but otherwise Im not a fan.

 

Hmm. That’s interesting. I just don’t see why a lighter rotating assembly. If strong enough. Wouldn’t be anything but better in regards to high rpm stability

 

harmonics come into play when you go too light. if you run a light flywheel for instant's but you still have a 11 pound primary clutch loaded with a ring gear on it. if the flywheel isn't half the weight? bad harmonics will either destroy the drive clutch or the crank. Mercury sno-twister's in model year 1976 found that out. there thunder bolt ignition system with a very light flywheel destroyed the arctic- cat hex drive clutch in 5 laps. 340/440 motors the 250 was brand new and had a balancer added to the flywheel. the fix was to add that to the 340/440 motor. problem fixed and actually made the sled's even faster.

 

the 650 crank isn't that much lighter. it won't be a issue. the crank would be the least of the issue. and mtn. sleds get beat on way worse then trail or lake race sleds. so if the 900R is good in the mtn. segment? it will surely be in a trail sled. 2 years tops the 850 is gone. they will make more money with a 900R why would guys want a 850? it will be 650 or 900 two stroke. that what you will have.

 

If something can hold up in the mountains wot literally non stop a trail application should be cake. Why would a mile long pull on a trail or lake be any harder on a motor vs wide open up the side of a mountain for a mile?

 

Mountain sleds do not have the shock loads trail sleds have.
Especially studded sleds.
Sure mountain sleds run wot but track loads not the same.
What’s hard on cranks is sudden shock load on clutch which can lead to crank twist.

 

I'll say this, I'm a pretty damn hard trail rider. I've also been fortunate enough to ride out west in some steep and deep. I agree with the shock loading comment to an extent, but the engine/drive train get absolutely abused in the mountains! Besides running top speeds holding it wide open on the lake for a couple miles, I've never heald a sled wide open as much and as long as I did out west! Most of the guys I meet out there top end their sleds at least once a year, if they don't pop, they do it for maintenance. Hell, there are services out there that will go rebuild your motor right there in the mountains! That's bad ass....

Moral of my story is, those guys wring the piss out of their engines!

 

Agreed. But also believe shock loading is just as severe on mountain sleds if not worse in some instances. 3” paddles on a 155-165” track loaded up with wet snow when bouncing around the terrain in the mountains is brutal. It’s bad with studded sleds too don’t get me wrong. But I think with a studded trail sled the shock loading is more linear as compared to a mountain sled that is digging for traction and catching whatever is under the snow. Whether that is a frozen layer, frozen tracks, trees, rocks, or whatever else, there is an immediate impact on track and drive train.

 

Not sure what all the debate is about ? You can have your 9r or whatever, if it doesn't have a hair dryer on it the boost will run by it all day everyday . Oh and to add the 9r has the same warranty as the boost 2yr.

 

At current boost levels at sea level, it doesn’t have much on the 9r. Plus, some don’t want the added complexity… just more things to go wrong with it. I feel the same way about a truck anymore… keep it simple, no big screen display, no turbos, no cylinder deactivation management system, no 10 speed trany, and diesels are cost prohibitive unless towing capacity is needed.

 

Sounds like your gonna miss out on all the good stuff ! But each there own ! Polaris turbo system really isn't all that complex ....

 

Well "Food for thought" to add to the interest in the discussion. Jesse James and Bruce at Southside Sales & Service are working on a new one that has my interest.
They have a brand new 2023 XCR and a brand new Polaris 9R mountain edition engine that they are going to be plopping in it and then pounding the hell out of it.
So far I've heard no concerns of the 650 Crank being something they are nervous about. It should be on the snow in a couple weeks.

 

Yes. Aren’t they calling it a Boost killer?

 

Two different sleds for two different intentions is how I see it.
You want long legs and big steam for the longer straight pulls than the Boost is your sled.
The 9R is snappy, quick revving and sounds like a blast to me but I've never run one.

I've read here that one of our H.C.S members has an 850 Tune that spanks Boosts, 900 or 9R's? Can't remember who that was?

 

I’m still rocking the 19 SBA 800 lmao. However I rode with my buddy in Maine last month with a 22 gade 850. We both have trail cans and stock everything else. I have the 1.6 track he has the 1.5 ice. From I think 50 or 60 we did a run he got the hit and then I started to walk away from him. So leaves me to believe I can make the little 800 scoot out with some love.

 

When I was running 800
We tested bmp pipe, y pipe, muffler, head. It was a half sled length faster than my stock sled. Same sled same track, hard pack
Then we tried a bunch of different clutching on bmp sled and didn’t get more then half sled faster

then went back to trailer with my stock sled and put pipe mod pipe on and it ran 6 sled lengths in front of bmp stuff

my buddy sold bmp stuff and bought pipe mod and we were back neck and neck
Pipe mod would lay over after back to back hard drag racing with no cool down, run scratchers and venting helped a bit.

 

So you’re saying when not the pipe would start to loose it’s over performance? I know BMP is hot in that regard as there’s doesn’t fall off when you start to heat it up.

 

If I remember correctly on THE 800 the BMP kit was the most $$$ and wasn't very impressive without adding their tune with it.
On the 800's in the cheap and simple department the SLP Pipe was the simple and easy no argument gain.

We are way off topic here talking of 800 mod's in a Boost 2023 BCM Head Mod thread?? For a second here I forgot where we were when I responded.

 

Lmao that’s because I was looking at the BCM side of things and then it just ran away from there lol.

As for the pipe, I haven’t really looked into SLP. I was just starting to research the “pipe mod” side of things. I just wanna wave bye bye to all my buddies on doos talking shit 🤣🤣