'12 rmk pro 600 with inconsistent power fade

[t30mg]

Testing my boys new to us 2012 rmk pro 600 today before we head west today.

Starts and runs great until you go WOT.
Then more often than not it cuts out to around 6000 rpm and will hold that until you let off. I should add that while stuck at 6k,it is running on both cylinders and not sounding rough.

Then if you let off and pin it again right away, it will usually rev to 8k again. Sometimes it will hold it for several seconds, sometimes it instantly cuts back out.
Sometimes from idle, it will rev full.
Sometimes from idle, it won't past 6k rpm.

But always if you are at even slightly less than full throttle it run great and not fade out.

Primary spring is good, weights are new 10-56.
I know in theory it could over rev at 1700' with those weights, but remember that several times it never even got to 7k rpm before cutting out.

Any insight on what can cause this?
It really feels like a electronic governing to me...

 

[dktraw]

Last time exhaust valves were cleaned? New fuel filter? Aftermarket can or stock?

 

[Bocephus]

lift the rear up, take the clutch cover off, and run it. make sure it looks like both clutches are functioning correctly.


the rollers that the weights roll against in the primary.......do all 3 roll freely? any flat spots on the rollers?


if you just bought the sled, do you know if it has fresh gas? 87 or 91 oct? is the octane resistor in the correct spot in the wire harness (above/behind the clutch cover)


fuel filter is problematic item on the proride chassis. they need to be changed every so often (im not sure what the symptoms of the filter being partially plugged are, i was just told about this issue by buddies that run pro's)


does it have a bunch of aftermarket garbage on it? exhaust? head? reeds?

 

[t30mg]

It's completely stock. It was almost out of gas, so I put some 87 non eth in it.
I'm not sure on the resistor, i guess I'll have to read up on that and see what it's set at.

Funny thing is though, if i use slightly less than full throttle, it goes really good.

 

[Bocephus]

i just checked about that resistor.......it is actually for ethanol or non-eth gas........NOT OCTANE. i believe it recommends 91 oct no mattter what. i doubt thats your problem, im just correcting myself


here is more info on it http://www.snowest.com/forum/showthread.php?t=287784


start watching this video around 2:00. it will show you where its at https://www.youtube.com/watch?v=n1TwzsRRrB8

 

[ak]

How many miles?
Compression numbers?
What is the coolant temp when this is happening?
Clean power valves?

56 gram weights are to light it will pull 64 gram weights at 1700 ft on the flats, but 62s work better at that elevation if there's any climbing. If it has more than 800 miles on the stock primary and secondary springs replace them they don't last. I ran my 2012 600 on 87 octane non ethonal at sea level and it ran good.

 

[xc6rider]

Test/set TPS, add to list of things to check.


Edit: Double check those weights! Not sure factory spec weights for 1700, but 58's seem low to me, and would cause it over-rev like you mentioned. I think we run 56's at 9000ft +

 

[t30mg]

Test/set TPS, add to list of things to check.


Edit: Double check those weights! Not sure factory spec weights for 1700, but 58's seem low to me, and would cause it over-rev like you mentioned. I think we run 56's at 9000ft +

Just got the weights from the dealer. Stock weights are 58 and are good to 6k'. 56g for up to 11k' i was told. So I know it COULD over rev, but that is why I said it sometimes/often cuts out around 7k rpm. No rev limiter there.

Will run perfectly and consistently above 7k rpm if I just stay a little off of wot.

 

[ak]

Put some 62 are 64 in there if your going to ride at that elevation. Report back with your findings

 

[t30mg]

Again, its only a test ride to check it out b4 going to elevation.

Besides, my '13 800 pro has 60g in it and it ran perfect in the exact same conditions today.

I wonder if the 600 really requires heavier weights than the 800 to do a side by side test run?

 

[t30mg]

Just drove it in the shop.

One other symptom it has is while driving slow, 4500-5000 rpms, it cuts in and out like your playing with the kill switch. Give more gas, and it cleans up.

Another faulty tps symptom?

 

[xc6rider]

Very well could be a TPS issue. Worth checking I'd say

 

[t30mg]

Leaving in 21hrs....i hope.

Playing with it with the track off the floor and have found that with the throttle stationary at around 2300 rpm it will run up and down and actually die.

Is the tps adjustable?
Can a guy just try trial and error at this point to try improve it?

 

[Bocephus]

Does the yellow check engine light come on on the left side of the gauge cluster when it cuts out?


I believe the throttle position sensor is just an electronic plug in sensor..... Nothing is adjustable.

 

[t30mg]

No lights coming on.

There is a sensor on pto side of throttle bodies that is mounted with screws through 2 slotted holes.

 

[t30mg]

Also at the lower 2000s when it cuts out, if i spray a snort of fuel in the air box, it picks up and runs smooth for a bit.

Seems like something is telling it to cut the fuel back at certain throttle settings.

Tried the eth/non-eth resistor in both settings and couldn't see a difference.

 

[t30mg]

So I just pulled the tps and tested it with a good fluke meter. I pulled the ohms off of center post and 1 outside post. I found while turning the shaft, the ohms increased. Slightly off of idle, the ohms decreased slightly and then continued increasing all the way to the end.
So I think that explains the dead spot around 2300 rpm, because i could move the dead spot by adjusting the tps while running.

But on the high end of the sensor, it was very consistent in its increasing and decreasing with my inputs on the shaft.

Pulling from the center post to the other edge post gave me a high value that decreased as i turned the shaft. It gave same results as the first test, only with descending numbers rather than ascending.

So while that was interesting, I don't think I'm any closer to solving the original problem yet....

 

[xc6rider]

Could also be throttle cable adjustment and the throttle safety switch...

 

[t30mg]

I might be onto something....

Decided to clean the power valves as a precaution, and found the plug wires had rubbed through the pv pressure line where the were zip tied together.

So the pv on the mag side could not have been pulling open all the way i think.

But would the computer pick up on that an limit me to 6k rpm??.

 

[xc6rider]

Dont believe the ecu would pick up on any of those valve hoses being rubbed thru...