High RPM DET

The wife and I were out groomed trail riding all weekend and my new to me 2011 Pro RMK 800 ran great all weekend (scratchers down, 127 degrees).

Except....when I mashed the throttle to the stop or got on it hard down a long smooth stretch of road where I could really get on it.

Then it would immediately go into DET mode, every time.

Shut off, restart...ran fine, until I repeated the high speed/rpm process again, then it would go back into DET.

I bought the sled used last season with 2500 miles on it. Immediately tore the top end apart and installed a MTNTEK Fix Kit in it.

Inspected skirts for cracks, got a professional hone job, ensured proper ring gaps, etc...

I installed a new fuel filter, made sure the reeds were good, made sure I had yellow injectors, etc.

I am using Redline Snowmobile Oil in the oil tank, turned up the oiler 3 turns, and pre-mixed the first tank full after rebuild at 32:1 with Redline as well.

Using Ethanol plug only and premium fuel.

I waited till I got a good 100 miles on the top end before really getting on it and it has always run perfect at all other RPM's other than the very top.

When we were coming back to the truck last night I finally got on a smooth enough road to watch the Tach and it ran well up to at least 8,000 or so, then went into DET.

I only got to do it a couple times due to traffic on road, etc...but seemed pretty consistent to that amount of RPM's.


Could it be the clutch needing a couple grams of weight?

Could it be the Redline plugging new fuel filter from pre-mixing?

Too much pre-mix leaning out fuel through injectors? (Ran last tank with much less oil in it after 100 miles).

First fuel injected sled I've had, but I'm a pretty thorough retired aircraft mechanic....pretty careful attention to detail. :face-icon-small-win

Id appreciate any and all advice...I looked through the search function and DET's threads are all over the place, so if someone could help narrow down my search it would be a huge help.

diamonddave said:

Response to your PM.

I always add 2 grams more with a Fix kit.

Always.

The DET code pops up from an engine over rev or engine revving up to fast. When you're on the trail, there's much less load on the engine then when you're in 3 feet of powder. Without getting into helix and secondary springs, try throwing next size weights in it.

You should be able to pull 64 gram either Polaris 10 series or Bellybusters with a 140/330 primary spring at our altitudes.

A few MTNTK kit's Ive had to go with 66 grams at our alt's.

Now if you went with an aftermarket head, then I'd recommend knowing your squish.

The oil is not an issue with adding redline oil. I've been doing that since the dragon days but I do change mine each season.

Click to expand...

I'm running everything stock, including the head.

I just ordered a set of 10-64 weights today, so I'll give them a shot and see if that does the trick at our altitudes.

If not, perhaps I'll try the 10-66's later...hopefully it wont come to that?

Well crap...just went to pull my weights in anticipation of the ones I ordered getting here and guess what?

Someone had already put 10-64's in it...that's what I get for assuming it was still stock. Ugh!

So....does my sled have some other problem, or should I still add more (10-66's)??


P.S.,

It also has a bright green primary spring in it, so it would appear someone changed it out too?