Noise when letting off throttle

[NDFARMER95]

Ok guys I got about 75 miles on my 13. It's got RKT drop in(14.1), SLP pipe, HPS can, and PCV. Coming back on the trail from riding the other day I noticed a noise when I get off the throttle. It almost sounds like a really quiet wastegate on a turbo. Only noticed it on the hardpack coming back. Was in the trees all day on and off the throttle and nothing was out of the ordinary. Any ideads? thanks

 

[NDFARMER95]

Bump

 

[benltr]

quick drive maybe?

 

[Rev Kev]

Exhaust Valves??

 

[600ho]

Mine is the same set up and does it too. I have been hitting the det sensor so I figured it might be related to that

 

[NDFARMER95]

It's a standard so it has the chaincase. Shouldn't be hitting DET. 8350 with 50/50 AV to pump mix @ 9000'. What with the exhaust valves?

 

[ullose272]

My stocker does that faintly and my m8 mod did it. I think its normal

Sent from my SCH-I535 using Tapatalk

 

[obile]

i think what you might be hearing is brake whine..my 12 does this on the trail also the pads ar super tight on the rotor.read a post somewhere that there is no freeplay between the lever and the plunger on the master and needs to be ground down a bit to allow the master to fully retract to release the slave off the rotor. havent had a chance to try mine yet.try turning the rotor or even moving it . seems too tight to me. anyone else see this?

 

[NDFARMER95]

Na it aint brake whine. I had that on my 12. Cruising down the trail, snap the throttle, let off, and it sounds like a wastegate on a turbo. The first time I ever heard it was coming back on the trail after riding the whole day without an issue.

 

[modit]

I bet it is the exhaust springs vibrating. One option is to bend the tabs the springs attach to. This will make the springs tighter. The other option is to put silicone on he springs which will dampen the vibration. The silicone is probably the better option.

 

[NDFARMER95]

How come it never did it all day then all of a sudden on the way back? Could I use silicone on all the donuts too or not? I also thought it could be the belt or primary clutch. Idk..

 

[NDFARMER95]

bump

 

[robadoodle]

my '12 with the rkt drop in does the same thing (all day long not just coming back the trail on hard pack). i reverted to the stock exhaust upon installing the kit ( got rid of hps can). i kinda figured that the noise was always there and i just couldn't hear it over the hps can.? also thought maybe its a noise that is always there and with the unbalanced stock piston vibration eliminated now you can hear it? but i sure would like to know what it actually is.
btw mine goes into det once or twice a ride (even though its a '12 and you aint supposed to need a fuel controller) in consistent conditions/elevations with or without race fuel, eth plug or not. maybe this is related to the noise? boony box just came off backorder, anyone have any numbers running drop in kit and otherwise stock?

 

[NDFARMER95]

Hmmm interesting. It shouldn't cause any problems should it?

 

[gman086]

HPS can is tighter than stock to give more backcharge (makes the sled feel more "torquey"). Using it with the RKT kit and SLP pipe is a mistake - you are getting too much backpressure causing that popoff noise. HPS cans are for STOCK sleds only. Lose the can dude! Your sled will run cooler and better too.

Have FUN!

G MAN

PS - That's why you don't "mix and match" pipes and cans. The SLP can is more free-flowing to match their pipe (similar to stock can).

 

[NDFARMER95]

I realize I run that risk. I've read guys have the HPS can with the SLP pipe with no issues. What I'm wondering is why didn't it do it all day? Or the day before?

 

[gman086]

I realize I run that risk. I've read guys have the HPS can with the SLP pipe with no issues. What I'm wondering is why didn't it do it all day? Or the day before?

It's the combo with the higher compression RKT head, like I stated (yeah, some guys are getting away with HPS on SLP pipe but not with a head). You come back down off the mtn and the chances for deto go way up with that tight can because it's a holding a lot more heat, especially at the exhaust ports which is where you hear that pop off. You can run weaker springs in the exhaust valves which helps with this too (a must with those types of exhaust mods if you ask me). Been there, done that.

Have FUN!

G MAN

 

[NDFARMER95]

So what your saying is as I went up to elevation I was losing compression, hence no noise. As I came back down I was gaining compression, the hps can is causing even more back pressure. The head tied with the hps was causing a whole lot of back pressure forcing the joints to popoff or the exhaust valves? I don't have a SLP can for a 13. Just a 12. I've heard a guy can make a bracket?

Could you fill me in about the light springs for the exhaust valves?

 

[gman086]

Correct. And the springs are the Polaris green/white part# 7041786-03. You have to understand that the springs Polaris ships with is the best compromise for "all elevations" and no exhaust mods. The more exhaust mods and the higher the elevation, the less exhaust valve spring pressure you want. That's why the BRP adjustable spring caps were so sweet - you could dial in the spring pressure you needed!

Cheers,

G MAN

 

[NDFARMER95]

Alright sweet. I made a bracket to put the SLP can back on. I'm going to try that first before I change out the springs.

Thanks a bunch, Kody.