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850 still Bogging and fouling Plugs after Break in

indydan said:
If you foul more then 2 sets of plugs after 2 hours the most important thing you can do is a leak down test.

Walking around in circles waiting for Polaris to solve the problem is as close to insanity as you are going to get.

Mid to high leak down.......Weird and bad symptoms always loom around.

Low leak down numbers ....... Only complaint ( My Arms hurt ) from hanging on.

Stop whining and order a leak down kit..... Read the directions and do the procedure.

If you own a 2 stroke and don't have a leak down tester you should not be allowed to ask questions about performance.

Pretty much end of story.... You cannot accurately speak about your own motor until you present the leak down numbers.

Sorry..... To be harsh.

But this thread in useless without leak down numbers.

We have not seen one fouled plug on our 850's

Dan
Click to expand...



I accept your apology, that was a little harsh.?
Appreciate the kick in the ass though....?

There are 3 850’s in our crew and they all are very similar in run quality (crap)
So the leak down kit is a good tool to have, as we expect to have a few more 2020 850’s in the fleet next season. However that is questionable as my 800 runs mint with 110hrs on it compared to all three of these POS’s.
 
Fouled my first plug this weekend. After ride before, sled sat outside in -20 and I moved it inside when it was probably -10 after brief warm up. I believe plug was fouled then in retrospect, and only one cylinder was firing. Got to trail head, probably 35 degrees, let warm up, same issue. Replaced PTO plug and ran well rest of day. Haven't had bogging issues other than first 1-2 hours. Currently sitting at 11 hours and 160 miles.
 
no_uh said:
Fouled my first plug this weekend. After ride before, sled sat outside in -20 and I moved it inside when it was probably -10 after brief warm up. I believe plug was fouled then in retrospect, and only one cylinder was firing. Got to trail head, probably 35 degrees, let warm up, same issue. Replaced PTO plug and ran well rest of day. Haven't had bogging issues other than first 1-2 hours. Currently sitting at 11 hours and 160 miles.
Click to expand...

11 hours and 160 miles... you’re homefree now?
 
MDEVO said:
I accept your apology, that was a little harsh.?
Appreciate the kick in the ass though....?

There are 3 850’s in our crew and they all are very similar in run quality (crap)
So the leak down kit is a good tool to have, as we expect to have a few more 2020 850’s in the fleet next season. However that is questionable as my 800 runs mint with 110hrs on it compared to all three of these POS’s.
Click to expand...

Herein lies the root of the problem... You have three sleds that do not run right and you expect to buy more for next year??? Polaris must be laughing all the way to the bank.
 
MDEVO said:
I accept your apology, that was a little harsh.?
Appreciate the kick in the ass though....?

There are 3 850’s in our crew and they all are very similar in run quality (crap)
So the leak down kit is a good tool to have, as we expect to have a few more 2020 850’s in the fleet next season. However that is questionable as my 800 runs mint with 110hrs on it compared to all three of these POS’s.
Click to expand...

Geeeeeez !! I was a little harsh !!

Sorry about that........... BUT in defense of my request for leak down numbers.

The quality of information will go off the charts comparatively speaking.

Everyone will benefit from seeing thes numbers..... And then all of a sudden the solutions why the sled is doing certain weird things we will know if the integrity of the motor is good or bad..

If leak down is bad the motor has to come apart.

Dan
 
Big10inch said:
Herein lies the root of the problem... You have three sleds that do not run right and you expect to buy more for next year??? Polaris must be laughing all the way to the bank.
Click to expand...

Big10, we must agree that the brand loyal guys mostly likely will never change.

Me included...... ??

And the OEM's will definitely make the following year motors better.

All OEM's need their die hard followers.

It's vital to a lot business's

Dan
 
I have a leak down tester from our Nitro Harley powered IQR .. these are very easy to use for that but what is the base number you set the supply regulator to?????

If I do 10psi it's easy math not much to go by like 100 but I don't know how much the seals and reeds can take !!!

I'm sure it's done at TDC correct ??
A second test with a sealed cylinder ( oil ) is probably in order also correct ???
 
indydan said:
Big10, we must agree that the brand loyal guys mostly likely will never change.

Me included...... ??

And the OEM's will definitely make the following year motors better.

All OEM's need their die hard followers.

It's vital to a lot business's

Dan
Click to expand...

Yup.
And some brand loyal guys get fed up and become brand loyal to a diferent brand.
 
The problem is that they are mapped too fat at 4500 RPM. Beyond 5000 they come on very strong. We have 3 in our group and they all ran the same except one has a quickdrive and is geared much higher than the 2 174's. The higher geared sleds may experience more problems to get past this fat RPM zone. You must ride aggressively and not feather the throttle around 4500 RPM or you will just keep keep pumping fuel in until a plug fouls. I have installed hotter spark plugs and my sled is running much more crisp. I know I risk detonation with hotter plugs but with 6 rides on them, I am getting much more confident. I do not recommend anyone try this without understanding potential consequences.
Also I have gone to lighter primary clutching but load the motor with the secondary setup that kicks-in more after the sled is moving.

I am very happy to say this setup is working well for me.

If you don't like how your sled is running, make the necessary adjustments or wait for Polaris to release a new map.
 
Teth-Air said:
The problem is that they are mapped too fat at 4500 RPM. Beyond 5000 they come on very strong. We have 3 in our group and they all ran the same except one has a quickdrive and is geared much higher than the 2 174's. The higher geared sleds may experience more problems to get past this fat RPM zone. You must ride aggressively and not feather the throttle around 4500 RPM or you will just keep keep pumping fuel in until a plug fouls. I have installed hotter spark plugs and my sled is running much more crisp. I know I risk detonation with hotter plugs but with 6 rides on them, I am getting much more confident. I do not recommend anyone try this without understanding potential consequences.
Also I have gone to lighter primary clutching but load the motor with the secondary setup that kicks-in more after the sled is moving.

I am very happy to say this setup is working well for me.

If you don't like how your sled is running, make the necessary adjustments or wait for Polaris to release a new map.
Click to expand...

Teth-Air:

What are you running for a secondary spring? Stock is Black/Red 155 222 65 and I see the next Team 2ndary spring is a Black/Purple 160 240 72 which might work. I'm thinking of keeping primary stock 74 to a a bit light (say 72-73 grams) and using that stiffer secondary spring to hold first gear longer (delay shift).

I'm sea level too FWIW.

OTM
 
Question

Why is it that people ask the same poor performance questions on just about every snowmobile made before doing the basic troubling shooting first ?

As soon as you have low-end to Mid-range performance problem the first thing that should be done is a cylinder leak down test.

All these problems...... The answer can not be found until you know your motors leak down percentage on each cylinder.

If the cylinder leak down is awesome then the problem is worth discussing.

You should not own a snowmobile unless you have a leak down tester.

You can find them on eBay, or Amazon.

Heck....I will put them on our website if that is easier.

I would absolutely love to see just one person with low end performance post his leak down numbers.

Dan
 
3-850’s in our crew, all having poor run quality, had new mapping installed this week. So far 1 of three has blown up! Apparently the mapping works great until they pop!
Don’t have much detail yet but crossing fingers another doesn’t go on us today....������*♂️
 
Last edited:
indydan said:
Why is it that people ask the same poor performance questions on just about every snowmobile made before doing the basic troubling shooting first ?



As soon as you have low-end to Mid-range performance problem the first thing that should be done is a cylinder leak down test.



All these problems...... The answer can not be found until you know your motors leak down percentage on each cylinder.



If the cylinder leak down is awesome then the problem is worth discussing.



You should not own a snowmobile unless you have a leak down tester.



You can find them on eBay, or Amazon.



Heck....I will put them on our website if that is easier.



I would absolutely love to see just one person with low end performance post his leak down numbers.



Dan
Click to expand...
I have been staring at my leakdown tester for many years and now I will use it thanks to Dan.

Sent from my SM-G920W8 using Tapatalk
 
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