Patriot 850 rattling/knocking noise

lilkev · Feb 13, 2019

Hello there, i am wondering about a rattle noise in the engine (i think). I have an sks 850 146. It runs perfectly fine just that when you let off the gas from high rpms it makes some kind of rattling/knocking noise in the engine.

TheBreeze · Feb 13, 2019

My ski tips rattle on mine. I’d check there just to see.

lilkev · Feb 13, 2019

TheBreeze said:
My ski tips rattle on mine. I’d check there just to see.

My ski rattles aswell, but that is not it. It is something in the engine compartment for sure.

d8grandpa · Feb 13, 2019

Mine has done this from new, 41 hrs and 500 miles now. I couldn’t figure it out for the longest time what was going on. Sounded like chain case or drive shaft.
But after playing with on off the throttle a lot i am convinced it is something going on in the engine that echos through the exhaust. It only happens doing down hill descents in harder snow and the second you tap the throttle it goes away. So it is something in the engine when it is decelerating.
Other than an irritating noise it doesn’t seem to affect anything. I have been waiting for the new tune to come out and see if that has any effect on it.

kanedog · Feb 13, 2019

lilkev said:
Hello there, i am wondering about a rattle noise in the engine (i think). I have an sks 850 146. It runs perfectly fine just that when you let off the gas from high rpms it makes some kind of rattling/knocking noise in the engine.

Post a vid so we can all hear it. Its hard to diagnose from words but it was a very good description!

Sent from my SM-G920W8 using Tapatalk

willjogervais · Feb 13, 2019

I'll guess it's the quickdrive belt. I just skimmed the earlier posts, but can u only here it after letting off the throttle on a descent? Kinda sounds like a ratcheting? Obviously not the track. I never heard it on my 800, but for whatever reason it is noticeable on the 850. If that's the sound you are hearing, dont worry about it and keep pounding on it.
Just reread the OP, if it's coming from the engine, that is not the noise I was referring to

no_uh · Feb 13, 2019

I think I know what you are talking about. Sort of a light rattle from engine area when you let off throttle. Maybe more noticeable before engine is fully warmed up but I'm not sure on this - it had me concerned at first but I figured it was normal after I logged more time and I haven't been paying as much attention the last couple rides. I have a 163 with QD, 300 miles.

indydan · Feb 14, 2019

I have mentioned this several times on different threads.

You you own a high performance 2 stroke motor you owe it to yourself and anyone you talk with about the performance of your motor to buy a leak down tester.

They are very inexpensive

It's really not fair to even ask questions about your motor unless you know the cylinder sealing ability..... ( compression tests do not work the same way )

Depending on your experience level using a leak down tester ( you must also have a small air compressor ) ....... In under 20 minutes you will know if your motor is in great to poor condition by % of leakage.

And what's more important...... If you do this procedure several times you will see 1 or 3 very important things as you put more miles on your sled.

Your leak down tests over a short period of time with show either....

1- the motor leak % is getting lower.
2- the motor leak % is getting higher
3- the motor leak % is staying the same

If the leak % goes up form one test to another the top-end is junk.

There is really no run abilities questions that can be fairly asked without knowing your motors leak down numbers.

People have been asking where you can get a decent leak down tester, my first one was from a snap on dealer over 35 years ago and I believe it was just under $250 dollars.

We have since purchased several new ones and tested them against each other.

We ordered fair amount of them to hopefully put on our website yet this week.

Ours will come with detailed instructions how to perform this test correctly which most leak down tester fail to supply in the kits.

Or you can buy one from your local Snap on, MAC dealer, Matco dealer.... And so on.

All performance problems cannot effectively be trouble-shot without a leak down test.

Dan

Teth-Air · Feb 14, 2019

My pull start handle rattles at a certain rpm, usually on deceleration.

snowmobiler · Feb 14, 2019

might be a empty beer can under the engine

volcano buster · Feb 14, 2019

Exhaust valves?

shortstuff · Feb 14, 2019

My pull rope handle rattles as well at a certain rpm decelerating. Makes a heck of a racket.

Sent from my SM-G930V using Tapatalk

Scott · Feb 14, 2019

I rode around in the field a bit the other night. My sled was cold and slow to warm up... I was taking it easy just puttering around with really short braps that didn't go above midrange.

I was hearing a weird vibration sound as I accelerated and slowed down. Couldn't figure it out. Sounded like it was mostly on the mag side by the exhaust.

Was it rich and fat? Detonation? Quick Drive? Exhaust? Recoil? Crank?

NOPE!!!

Finally, after a couple of minutes, I discovered it.

It was my skegs slicing the icy crust under the couple of inches of soft powder.

Another time, a couple years ago, I was hearing a weird sound...my thoughts went all through the same scenarios.
Turns out the rubber boots on the steering arms were both broken and the nylon grommet/ring had slid down and was vibrating near the heim joint by the spindle.

indydan · Feb 14, 2019

snowmobiler said:
might be a empty beer can under the engine

BINGO !!! That's it :face-icon-small-hap

Killer Time Racing · Feb 15, 2019

volcano buster said:
Exhaust valves?

My thoughts exactly .. exposed mechanical part now probably flutters some on decel !

TRS · Feb 15, 2019

Two things are making noise on mine. The IFS spring rattles hard when at idle along with the ski to spindle pocket while set in the narrow position.

minus40 · Feb 15, 2019

indydan said:
I have mentioned this several times on different threads.

You you own a high performance 2 stroke motor you owe it to yourself and anyone you talk with about the performance of your motor to buy a leak down tester.

They are very inexpensive

It's really not fair to even ask questions about your motor unless you know the cylinder sealing ability..... ( compression tests do not work the same way )

Depending on your experience level using a leak down tester ( you must also have a small air compressor ) ....... In under 20 minutes you will know if your motor is in great to poor condition by % of leakage.

And what's more important...... If you do this procedure several times you will see 1 or 3 very important things as you put more miles on your sled.

Your leak down tests over a short period of time with show either....

1- the motor leak % is getting lower.
2- the motor leak % is getting higher
3- the motor leak % is staying the same

If the leak % goes up form one test to another the top-end is junk.

There is really no run abilities questions that can be fairly asked without knowing your motors leak down numbers.

People have been asking where you can get a decent leak down tester, my first one was from a snap on dealer over 35 years ago and I believe it was just under $250 dollars.

We have since purchased several new ones and tested them against each other.

We ordered fair amount of them to hopefully put on our website yet this week.

Ours will come with detailed instructions how to perform this test correctly which most leak down tester fail to supply in the kits.

Or you can buy one from your local Snap on, MAC dealer, Matco dealer.... And so on.

All performance problems cannot effectively be trouble-shot without a leak down test.

Dan

What do you like to see for % leak, whats average? And when would you repair, just when it goes up or you have a number?

TRS · Feb 15, 2019

minus40 said:
What do you like to see for % leak, whats average? And when would you repair, just when it goes up or you have a number?

Polaris historically was 5%. That is where I believe max should be on a 2 stroke.
After the push for leak down tests instead of compression tests here on SW, by many members, they moved the goal posts.

indydan · Feb 16, 2019

TRS said:
Polaris historically was 5%. That is where I believe max should be on a 2 stroke..

I agree completely.

Over 5% it either needs rings or complete piston kits. ( almost always complete piston kits )

Keep in mind...... If your sled is new or very low miles and it's a little over 5% make sure you ride it a few hundred miles more and take another test to see if it is getting better or worse.

Dan

indydan · Feb 17, 2019

Leak down test

Before anyone does a reflash, you should first do a cylinder leak down test.

Motor Performance before the reflash...... And performance results after reflash are worthless without leak down numbers.

The big problem with reflashes is...... ( we do NOT know the leak down % on the sled Polaris is using for the mapping ).

Are they using a brand new motor ? With 3-1/2% leak down?

Are they using a 500 mile motor ? With 1-1/2% leak down that had a great cylinder finish and rings sealed up nice ?

Are they using a 500 mile motor ? With 7% leak down that has rings that are on their way out the door...... ( basicly junk )

You see if we knew everyone's numbers...... Then we could see who's sleds the reflash works on and if there is a correlation to the leak down numbers.

And there will be........

If you build a map on a sub-par motor the map is basicly worthless to everyone except another guy with the same sub-par motor with the exact same leak down.

If you build a map on a broke in motor with 1-1/2% leak down...... The Map will be awesome for everyone with a good solid top-end with good % numbers.

As I have said...... All the different results are worthless to the masses without leak down numbers

Dan

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