Pro Cylinder Wash Pic Questions...Advice appreciated!

Vincenthdfan · Feb 25, 2017

My 2011 Pro RMK had 2500 miles on it when I bought it.

I immediately pulled it down and installed a MTNTEK Fix Kit as a preventative measure.

I did a careful break in on it and it runs really well.

I've had it out a several times this season trail riding with the wife on her sled since then and put a few hundred miles on it.

Only issues I have had, was it had been going into DET Mode anytime I jabbed the throttle really quick in mid range or let it get into the highest RPM's on groomed trails when riding with my wife.

I found the primary clutch had 10-64 weights in it and we were at 1800'ish elevation when I was hitting DET.

So, I installed 10-66's and it seems to have all but eliminated it riding in the same areas.

I found however, that if I tried a few times I could still get it to hit DET on top end occasionally.

So...I figured I'd scope the top end to make sure I don't have an air leak, or something to that effect.

It appears, according to what I have been reading on the web, that this isn't that unusual judging by these pics?

Is that correct?

The old stock Polaris pistons I took out were completely dark across the tops without any signs of wash like these have on them.

At any rate, if this is indeed normal, do I need to throw more weight in the clutch to get rid of that last little bit of DET I'm having?

Thanks!

Octanee · Feb 25, 2017

This may or may not help, I just got a PRO and It's turbo'd, clutching was way off and it would rev fast then boost would hit and yeah It just wanted to rev to the limiter and got a lot of DET codes happening whether it really was detonating or not..?? , once I got my clutching Dialed in it's much much better, no more det when hitting the throttle to let it rev out. Maybe your sleds revving too quick still and/or the rpm when wide open is also too high?

as far as piston wash goes I can't say much, but I know these engines seem to burn pretty clean, so it may take a while to get it to really show much of a carbon footprint on the pistons, I had a turbo ski doo 1000 and every few rides I'd pull the heads to check the wash and It never had much for carbon and burn patterns on the piston and took a while to build up.

diamonddave · Feb 26, 2017

Before you throw more weight at it, what kind of RPM are you getting in a full deep snow climb?

Do you primarily just ride groom trails?

What Helix and spring are you running in your secondary? How old is the sec spring? I can tell you the sliding sheeve bushing has to worn and is sloppy. I see them wasted/worn out in 1,000 miles. Could be a combination of both in your case.

Clutching can be a fine line between these low-track load issues and deep snow performance. Given your riding style, you can throw 10-66's in it to get rid of the once-in-how-often DET you have but you may be giving up too much high load-top end RPM, deep snow performance depending on what your current RPM are now.

I would try a new spring and sliding sheeve bushing first. A custom helix can help. Roosterbuilt has a special cut that works well for low load trail manners and high load deep snow.

Some guys leave all alone and will try to ride it as is and manipulate their trail riding manners to keep their deep snow perf.

It's up to you. But this is a good problem.

Sounds like your MTNTK Fix Kit is making power.

Vincenthdfan · Feb 26, 2017

The secondary is all stock and has never been apart.

I still have the 10-66's in it and it pulls really good when I get on it and will jump out of a standing start very hard...impressive honestly.

That's kind of why I'm hesitant to go to even heavier weights.

I do primarily ride trails with the wife, with occasional side hill pulls while she hangs out and takes a break, lol.

I don't really do much off trail because I don't have any other riding partners and don't really want to risk going out by myself.

Biggest reason for scoping my pistons...I wanted to ensure I wasn't getting a lean detonation and eroding my pistons (been there. done that on motorcycles!).

jim · Feb 26, 2017

Real easy to diagnose if the det is from revving or actual det...try adding a few gallons of race gas and see if it goes away.

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Pro Cylinder Wash Pic Questions...Advice appreciated!

Vincenthdfan

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Octanee

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diamonddave

Chilly’s Mentor

Vincenthdfan

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jim

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