09 Summit 800 with Rkt 14.8:1 head, stock pipe, skinz can, everything else stock. What's everyone running for jetting?
jetting with rkt head
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R
RKT
Well-known member
430 main jet.. ran mine this year for 500 miles.. Also installed the 07 Summit needles but only did this for adjustability reasons
uuuuhhh.......... Wouldn't you want to know the elevation the sled will be ridden at ?
430's? why does that sound small?
09's should have DPM, compensating alt. & temps.
Dpm
True, the Doos have DPM, but you still need a rich enough base line or it will burn it up.
I can never figure out .... 1. How people can ask jetting suggestions without giving their riding elevation. and 2. How people ( especially professional engine builders) can actually give advise without knowing the riding elevation. It is 2009, maybe elevation doesn't play a role in jetting anymore, lol
True, the Doos have DPM, but you still need a rich enough base line or it will burn it up.
I can never figure out .... 1. How people can ask jetting suggestions without giving their riding elevation. and 2. How people ( especially professional engine builders) can actually give advise without knowing the riding elevation. It is 2009, maybe elevation doesn't play a role in jetting anymore, lol
R
RKT
Well-known member
True, the Doos have DPM, but you still need a rich enough base line or it will burn it up.
I can never figure out .... 1. How people can ask jetting suggestions without giving their riding elevation. and 2. How people ( especially professional engine builders) can actually give advise without knowing the riding elevation. It is 2009, maybe elevation doesn't play a role in jetting anymore, lol
VERY SIMPLE..
The compression ratio tells me wht elevation they ride at.. Afterall.. It is my head and my engine specs... So, I can tell what and where they ride by what I designed and sold them..
And on Ski Doo's elevation does NOT play ANY role in jetting.. I run the same jets at 10K ft as the guy in MN at sea level..
Kelsey
J
JohnnyH
Well-known member
VERY SIMPLE..
The compression ratio tells me wht elevation they ride at.. Afterall.. It is my head and my engine specs... So, I can tell what and where they ride by what I designed and sold them..
And on Ski Doo's elevation does NOT play ANY role in jetting.. I run the same jets at 10K ft as the guy in MN at sea level..
Kelsey
LOL
CHEERS Kelsey!!!
I wondered when the "biting retort" was coming. When I first read the thread I thought wow that's the cool thing about the forum, ask a question and get an answer right from the horses mouth. Then it kept going on and on and I'm thinking what gives? Did they not recognize the 2nd post as the guy that designed and built the head?
VERY SIMPLE..
The compression ratio tells me wht elevation they ride at.. Afterall.. It is my head and my engine specs... So, I can tell what and where they ride by what I designed and sold them..
And on Ski Doo's elevation does NOT play ANY role in jetting.. I run the same jets at 10K ft as the guy in MN at sea level..
Kelsey
Not trying to get into a pissing match, and don't take this as a personal attack in any way...
BUT..... not everyone who has an RKT head bought it from you. You may be able to tell what and where they ride if you sold it to them, but it is definately possible that the guy bought it used from someone who rides a different elevation than the original owner. I admit I went out on a limb and assumed that since the author of the post was asking forum members about jetting, I figured he didn't buy it from you. ( One may think if he did buy it from you, he'd already have the info from you)
And 2nd, I happened to buy an RKT head from an engine builder you supply heads to and he asked me what specific elevation I ride. I figured it had to do with jetting. But from your post, maybe it had more to do with the compression ratio? Although he did send me new jets that were a "baseline to get me in the ballpark" which suggested to me that not all elevations use the same jet size
I admit I deserved the slam for being a smart a**, but it still seems weird to me that all Doo's would be jetted the same from sea level to 10,000 feet.
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If the sleds got DPM.
0-10,000, pretty much set it-forget it
0-10,000, pretty much set it-forget it
X
Xrider
Well-known member
I was told the same BS by a head builder (RKT) a couple years ago. "14.5:1 at 5000', 91 octane will be fine" I will admit it ran pretty good for one little shakedown ride. Second ride completely trashed the mag side piston and cyl. Rebuilt the motor (at my expense of course) and switched to Union Bay's 13.5:1 head and it's been fine ever since.
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jetting
I bought a sled with the drop-in pistons and head already installed and it had 14.5 to 1 domes in it. It came from an altitude of 10,000 feet. I ride anywhere from 5500 to 10,000 feet. I changed the domes to 12.5 to 1 to be safe. The sled had 440 jets in it and still would get the pyro up to 1300 degrees. I have now changed my jets to 460 and testing this weekend hoping for lower egts. Thats all I know. You got me!!!!!!!!!!!!!!!!
I bought a sled with the drop-in pistons and head already installed and it had 14.5 to 1 domes in it. It came from an altitude of 10,000 feet. I ride anywhere from 5500 to 10,000 feet. I changed the domes to 12.5 to 1 to be safe. The sled had 440 jets in it and still would get the pyro up to 1300 degrees. I have now changed my jets to 460 and testing this weekend hoping for lower egts. Thats all I know. You got me!!!!!!!!!!!!!!!!
2 times now with trying to get my jetting figured out she wouldn't pull over 8000 rpms at riding area, clickering up made no difference. On the way back down she would pull over 8000 rpms and finally run right when on the trail.
1st time was at 4,500' (parking lot) to 6,000' with 420's
2nd time was at 6,000' " " to 8,000' with 410's, plugs looked good and reading 1100 on egt's.
I'm sure air temp had some play in this since the 1st time was cold and the 2nd time was warm.
I would try 400's so she'll run right at 8,000' but then running at 4,000' would make me real nervous even with running 1 gal of race gas.
1st time was at 4,500' (parking lot) to 6,000' with 420's
2nd time was at 6,000' " " to 8,000' with 410's, plugs looked good and reading 1100 on egt's.
I'm sure air temp had some play in this since the 1st time was cold and the 2nd time was warm.
I would try 400's so she'll run right at 8,000' but then running at 4,000' would make me real nervous even with running 1 gal of race gas.
So you are running 460's and that is not lean when you get in high elevation??
Lean? How could that be lean in higher elevation? The higher you go the fatter or richer your sled gets. Sled requires less fuel for less air. Not all sleds are the same, but mine sure seems to require more fuel to keep egt temps down. So, no actually it would be rich by standards.
