Oh No! Another Pro Burn Down Thread – Sorry

RMK900Tractor · Feb 26, 2018

Oh No! Another Pro Burn Down Thread – Sorry

Just looking for some opinions,

2014 Pro RMK 800 with 2800 miles
2015 Installed MTNTK Fix kit last year and rode approximately 500 miles
Occasionally, I get a DET if at WOT then let off and WOT again quickly. If I ease back into it the second time then no DET. I have this issue quite a bit.
Not over revving - 8150 RPM max
2016 rode approximately another 500 miles. Had some minor missing issues but adjusted the connector pins on the injector / TPS harness and added some dielectric grease then ran great.
2017 road approximately another 500 miles. Broke clear portion of fuel cap so some snow many have gotten in.
- Cold night (-34 F).
- Next morning started to miss again (around 1 degree F)
- Changed spark plugs and caps
- Added fuel line antifreeze (isopropyl alcohol). Let sit for 15 minutes
- Sled started to run normally after restart
- Let engine warm to at least 100 F
- Went about 1 mile before the seizure.

My plan,
- Replace pistons with new MTNTK lightweight with Teflon coating
- Test fuel pressure
- Check fuel pump pick-up screen
- Replace fuel filter
- Replace injectors
- Do leak down test to check for crank seal/case seal leak
- Replace plug wires
- Pray

Any thoughts/suggestions from the community? (besides buying an Axys).

AdrenalineAddict · Feb 26, 2018

Sounds like you could possibly use my 2014 Pro engine parts and pieces I have listed in the swapmeet engine section.

400 mile perfect monoblock I'll sell for $500.00
2- 400 mile pistons- $75.00 a piece.

PM me if interested.

jshreds · Feb 26, 2018

Did you ever turn the oil pump up at all? Get the fuel injectors tested before just replacing them, they could be fine.

Octanee · Feb 26, 2018

Certainly an odd failure and the wear points on the pistons.... It's like she got super hot and melted? Perhaps a lubrication issue. Factory oil pump turned up? Many have found they run way lean from the factory which have led to engine failures.

RMK900Tractor · Feb 27, 2018

jshreds said:
Did you ever turn the oil pump up at all? Get the fuel injectors tested before just replacing them, they could be fine.

Yes, I did turn up the oil pump right after I got it. It was for sure using oil - filled it every day. Guessing 3/4 quart/tank??

RMK900Tractor · Feb 27, 2018

Octanee said:
Certainly an odd failure and the wear points on the pistons.... It's like she got super hot and melted? Perhaps a lubrication issue. Factory oil pump turned up? Many have found they run way lean from the factory which have led to engine failures.

I agree with the lean comment. I always struggle with DET, especially after the MTNTK kit install and on cold days. Thinking about adding a fuel controller and A/F gauge.

peaceofwork · Feb 27, 2018

Let's see a pic of the piston tops?
I have put methyl hydrate to clear ice but I hate doing it on 2stroke motors.
I think I would also drain out all the fuel and dump it in the wife's car- to start with fresh good fuel removes one more thing to wonder about.
Are your cylinder boars going to clean up ok?
A new 2 stroke oil filter might as well be on your list.

RMK900Tractor · Feb 27, 2018

peaceofwork said:
Let's see a pic of the piston tops?
I have put methyl hydrate to clear ice but I hate doing it on 2stroke motors.
I think I would also drain out all the fuel and dump it in the wife's car- to start with fresh good fuel removes one more thing to wonder about.
Are your cylinder boars going to clean up ok?
A new 2 stroke oil filter might as well be on your list.

Good idea on the filter.

I always hate putting the fuel antifreeze but at one time the manual mentioned 1 oz/gallon.

Attached is a pic of the piston top.

diamonddave · Feb 27, 2018

Sounds like you have a good plan (I like the injector replacement). I think the only thing I would do is tear down the lower end and replace the lower end seals.

-34F that's fricken cold.

peaceofwork · Mar 1, 2018

Seals are cheap insurance, every bit of thoughtfulness helps. Next up might be why not pull the crank and check the run out and to confirm the journals are phased right.
it would suck bad to eat another set of Pistons just because you can't wait to go riding. I wish you good luck but caution to deafinatly find the pre existing problem or to do every thing you can think of to help make sure it don't happen again.

RMK900Tractor · Mar 1, 2018

peaceofwork said:
Seals are cheap insurance, every bit of thoughtfulness helps. Next up might be why not pull the crank and check the run out and to confirm the journals are phased right.
it would suck bad to eat another set of Pistons just because you can't wait to go riding. I wish you good luck but caution to deafinatly find the pre existing problem or to do every thing you can think of to help make sure it don't happen again.

Good ideas, thank you for the input.

peaceofwork · Mar 1, 2018

Looking at the crown of your piston perhaps centre towards the exhaust side it looks like detonation or piston bits doing damage? Is your head damaged?
Next up is I am looking over the outer edge of the piston 360*for a wash pattern- I only see some wash pattern slightly on the intake side, my sled showed a deeper in from the edge in 360 wash when I opened it up for a look. Now the next thing I'll ask is if you look into your pipe is it wet/oily down the ports a little ways down or dry? One side or both sides?
If only one side burns down the crank seal on that side is suspect...as is the intake boot reed cage sealing area- upon disassembly are their any dirty trace line tel tail sighns that it's been sucking air?
Anyways thats **** I think about and it's only my opinion I,m sure this ain't your first rodeo.

peaceofwork · Mar 1, 2018

Ice in the fuel system weak fuel pump and gremlins

realbass · Mar 2, 2018

Tall pistons does not working correctly. We have a lot of customers who had same a lot of problems.

RMK900Tractor · Mar 2, 2018

peaceofwork said:
Looking at the crown of your piston perhaps center towards the exhaust side it looks like detonation or piston bits doing damage? Is your head damaged?
Next up is I am looking over the outer edge of the piston 360*for a wash pattern- I only see some wash pattern slightly on the intake side, my sled showed a deeper in from the edge in 360 wash when I opened it up for a look. Now the next thing I'll ask is if you look into your pipe is it wet/oily down the ports a little way down or dry? One side or both sides?
If only one side burns down the crank seal on that side is suspect...as is the intake boot reed cage sealing area- upon disassembly are their any dirty trace line tel tail signs that it's been sucking air?
Anyways that's **** I think about and it's only my opinion I,m sure this ain't your first rodeo.

I think what you are seeing on the crown of the piston is just carbon. The head is in good condition and no signs of broken parts getting smashed.

No, not much of a wash pattern on the intake side.

The pipe was dry on both sides and had a ceramic color. Not the normal golden brown but much lighter color.

I have not yet disassembled the intake boots or the PTO seal but I better. Lots of feedback on replacing this seal

Thank you for the feedback

RMK900Tractor · Mar 2, 2018

peaceofwork said:
Looking at the crown of your piston perhaps centre towards the exhaust side it looks like detonation or piston bits doing damage? Is your head damaged?
Next up is I am looking over the outer edge of the piston 360*for a wash pattern- I only see some wash pattern slightly on the intake side, my sled showed a deeper in from the edge in 360 wash when I opened it up for a look. Now the next thing I'll ask is if you look into your pipe is it wet/oily down the ports a little ways down or dry? One side or both sides?
If only one side burns down the crank seal on that side is suspect...as is the intake boot reed cage sealing area- upon disassembly are their any dirty trace line tel tail sighns that it's been sucking air?
Anyways thats **** I think about and it's only my opinion I,m sure this ain't your first rodeo.

Here are some pics from inside the Y pipe.

RMK900Tractor · Mar 2, 2018

Someone also mentioned the oil reservoir cap may be a problem. I took off the cap today and when I shake it - it makes a rattle sound.

However, if I try to blow air with my mouth in or out of either the inside or outside I am not able to make air pass through.

It would seem to me air should pass through to equalize the pressure inside the tank to atmosphere.

Does anybody know if this is normal?

XCaSSAULT · Mar 2, 2018

RMK900Tractor said:
Someone also mentioned the oil reservoir cap may be a problem. I took off the cap today and when I shake it - it makes a rattle sound.

However, if I try to blow air with my mouth in or out of either the inside or outside I am not able to make air pass through.

It would seem to me air should pass through to equalize the pressure inside the tank to atmosphere.

Does anybody know if this is normal?

They won’t vent properly at the 45ish degree angle they are at. Take a paper clip and heat it up red hot, then poke a hole or two (red arrows)for better venting. If it’s upside down for an extended period u might get a couple drips, nothing to worry about though

Dazzler · Mar 2, 2018

I have not had much luck with the mtntk kit on 2013 and up Pro's. We went back to OEM pistons and have not looked back.. I do agree that you should check for seal, fuel filter, or possible injector issue but I have had a couple poo 800's melt down after doing a mtntk install just to freshen up the top end. Both with under 500 miles on them.
Indy Dan has a good write up on poo 800 pistons in Polaris section on this forum. Well worth the read.
Good luck with rebuild.

Reg2view · Mar 2, 2018

The ball rattle is how the cap vents as the ball hits the plastic finger inside. Blow into it when the cap is square to the ground, or rattling around to see if it is venting. Doo cap with the one-way duckbill reed is an easy swap, too, then the rattle cap goes away for good.

Oh No! Another Pro Burn Down Thread – Sorry

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