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Discussion Starter · #1 ·
well i did it and ordered the rkt head for my 900. he seems like a nice guy too deal with and was telling me that the stock head design is pretty dam stupid. the way he said is it going to make a pretty good difference and may increase gas mileage some too because of the increased combustion efficency. hope its pretty good look really trick. says i will need to remove thermostat because u really dont need it. everybody i talked to on here said he makes good stuff as do the guys on snowwest. :div20: rtk head linky
 

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He makes a beautiful product. To bad it slowed my sled up! Thats right, slowed up. I lost mid range to top end. The sled comes out of the hole great then lays right down. I jetted down over 4 sizes! No detenation, no excessive heat. Cold cranking compression is 142 lbs. Not bad, but could be higher safely. I'm hoping Kelsey will do good and either repair, replace or refund. He might make a great high altitude head, but for us lowlanders, not so good in my book. So far.

:frech32:
 

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Discussion Starter · #5 ·
i guess ill see
 

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Discussion Starter · #6 ·
Originally posted by Maydaze@Oct 7 2005, 05:58 PM
He makes a beautiful product.  To bad it slowed my sled up!  Thats right, slowed up.  I lost mid range to top end.  The sled comes out of the hole great then lays right down.  I jetted down over 4 sizes!  No detenation, no excessive heat.  Cold cranking compression is 142 lbs.  Not bad, but could be higher safely.  I'm hoping Kelsey will do good and either repair, replace or refund.  He might make a great high altitude head, but for us lowlanders, not so good in my book.  So far.

:frech32:
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just a thought on the head both u guys that have them have 800s who knows maybe his 800 heads arent the greatest. i have heard from a few people the head on the 800 is a little more trick to work with. hopefully he will help u out.
 

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I used the head on my 700 and can't tell the difference from stock. Will know more this winter. Not bashing his product, but I know I didn't gain any mpg.
 

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Some of these "head shops" play 'bilers like a fiddle. Almost as bad as musky fishing... There are baits that catch fish and there are baits that catch fisherman.

Stock heads aren't anything pretty to look at, chit people bitch enough about the price of sleds these days... Aftermarket = full on wannabee bling/bling!

Looks all nice and purdy and provides the illusion that it's better than the stocker... It's basically psychological warfare, open your hood and there's a nice piece sitting there, your buddy's are tremblin that you're gonna spank em... The "head shops" gotta do something to make you drop your hard earned coin!
 

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Well, I just wanted to let you all know that I spoke with Kelsey yesterday about my 'head' problem. I had the head c.c.'d and I measured the squish. I then called Kelsey to see what he had made the head to see if it matches up. It did. I then went into detail about what I did and how the sled performed with his head the last 2 weeks of the year riding. He stated that at high altitude, he knows exactly how to make them perform. At sea level he knows what is a safe margin, but he also needs to build in a safety margin. Polaris pistons have a very small dome, not much more than a flat pistion. The rise is very minimal. The compression test showed that I could safely cut the head and add compression, but after doing so I would then need to recut the squish angle to not go below .040' overall including the piston to deck height. Kelseys head is 3cc's smaller than the stock head. (47.5 vs. 50.5) The squish was .042' on the head and my piston to deck height is .002'. So the squish is .044'. I am going to do some work on his head and I'll let you know how it performs on the dyno. I just wanted to let you know that Kelsey stands behind his product and will do whatever he needs to make you a happy sledder.

:beer:
 

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Just wanted to let you guys know I've been doing some figuring this week on the 2 heads and this is what I came up with.

Polaris stock head * 11.83:1 comp.
RK Tek head * 12.80:1 comp.

The RK head definitely has more compression than stock. The magic number for running on 92+ octane is below 13:1 if I am not mistaken. Any thoughts?

:beer:
 

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Discussion Starter · #12 ·
Originally posted by Maydaze@Oct 12 2005, 08:59 PM
Just wanted to let you guys know I've been doing some figuring this week on the 2 heads and this is what I came up with. 

Polaris stock head * 11.83:1 comp.
RK Tek head        * 12.80:1 comp.

The RK head definitely has more compression than stock.  The magic number for running on 92+ octane is below 13:1 if I am not mistaken.  Any thoughts?

:beer:
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yes at low alt it is about 13.1 i always ran my 700s at about 12:85 and no probs dont know about 800s though 92 oct
 

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Originally posted by Maydaze@Oct 11 2005, 07:18 PM
Well, I just wanted to let you all know that I spoke with Kelsey yesterday about my 'head' problem.  I had the head c.c.'d and I measured the squish.  I then called Kelsey to see what he had made the head to see if it matches up.  It did.  I then went into detail about what I did and how the sled performed with his head the last 2 weeks of the year riding.  He stated that at high altitude, he knows exactly how to make them perform.  At sea level he knows what is a safe margin, but he also needs to build in a safety margin.  Polaris pistons have a very small dome, not much more than a flat pistion.  The rise is very minimal.  The compression test showed that I could safely cut the head and add compression, but after doing so I would then need to recut the squish angle to not go below .040' overall including the piston to deck height.  Kelseys head is 3cc's smaller than the stock head.  (47.5 vs. 50.5)  The squish was .042' on the head and my piston to deck height is .002'.  So the squish is .044'.  I am going to do some work on his head and I'll let you know how it performs on the dyno.  I just wanted to let you know that Kelsey stands behind his product and will do whatever he needs to make you a happy sledder. 

:beer:
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Not to drag this fairly recent thread back up to the top, but the stock 800ves head has 45.7cc uninstalled head volume (UHV). Confirmed this with the Polaris High Perf Manual as well as cc'ing my stock 800 head (Marvel's Mystery Oil & graduated syringe). Stock 800ves compression ratio is ~13.3:1, FYI.

So, RKTek's head is actually LESS compression than the stocker (If Kelsey's is 47.5cc), but that's not necessarily a "bad" thing, either.
 

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I dont care what the manual says. I cc'd the head at a local automotive performance machine shop with the RK head right next to it. We cc'd them, back to back using alcohol, not oil. The stock head was 50.5 cc's with the plug. The RK was 47.5 cc's with the plug. The stock head combustion chamber is quite a bit deeper than the RK head. Albeit smaller in diameter with a much larger squish band, but the squish band on the stocker drops off from .040" to .195" before it goes into the chamber. Whereas the RK head started at .042" and was a much milder drop off until it hit the chamber. With my .002" deck height, the stock head on my sled is 11.83:1 vs. RK's 12.8:1 ratio. Thats fact, not fiction.

:div20:
 

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Like I said, I both measured mine and confirmed with the Manual. Not sure how there can be "two" FACTS, but you can also call Indyhead, SLP, or RKT and they'll also all confirm for you that the stocker has a 45.7cc UHV or a CR of ~13.3:1.

Something was wrong with your stock head, perhaps it was already modified by a previous owner (?). Not bashing you at all, but there is something going on with your stock head if it was that far off from spec.
 

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Now that I think about it, this might also explain why you saw no gains with the RKT head versus your "stock" head. If your "stock" head had already been previously modified to eliminate the various deficincies and have it perform better, then going to a different modified head may not have then shown the gains that others have normally seen. Lots of shops modify stock heads but yet still look completely stock, ie, HTG, Indyhead, Carls, etc. etc. It would also explain a bit on why you said the RKT head of yours fell flat on top-end - everything else being equal, more compression usually reduces top-end performance.

Or.... Polaris figured out sometime during mid-2004 production that their 800 head design sucks and thus made some significant changes without anyone picking up on it.... Because as you said, if you had yours measured and I personally measured mine using the preferred fluid and technique, then there's no way that measurement error could account for 5cc's difference..... I'd believe a .5cc difference, but 5cc's is a LOT of fluid.....
 

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i hope you guys realize that higher compression on stock porting does kill you top end. the engine does not rev out as hard. it makes good midrange and bottom end. just something to think about.
 

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Discussion Starter · #18 ·
indyhead had said a couple of month ago that the 800 head is more tricky to work with. he said they reshape the head and use a little lower comp and it works better.
 

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Discussion Starter · #19 ·
i got my head today. i will cc the stocker on the sled before i take it off and cc the new to know what i am starting with.
 

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Discussion Starter · #20 ·
here is pic of the stock head off of rtk site
 
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