Rk Tek 858

Shobiz6 · Oct 13, 2014

Im considering the big bore kit for my 2015 pro, i remember reading a while ago about some detonating issues that they were having.

Would like to hear from someone that had this issue and what ever happened with it? Did you solve it, what was causing it?

Are people still loving these kits? Some feedback would be appreciated:face-icon-small-coo

die hard poo · Oct 14, 2014

Interested as well.

wfieldin · Oct 14, 2014

Many variables to this question:

Elevation, domes, fuel, BD box settings, clutching etc...??

I have one that has/had the higher comp domes 15:1, it would DET at certain times when in the flats. I found that it is very heat sensitive as well. Once I removed the t-stat I did not have any DET issues but it was at the end of last season and I was riding at higher elevations too (10000+). I was running 1 gal 112 to 4 gal 91. Kelsey cut me some 14:1 domes which I have installed but not run yet, I would like be able to run straight 91, we will see. I expect that I will have to play with my BD box numbers but hopefully not too much. Static compression in Denver with 15:1 domes was at 137 lbs, 14:1 lowered 10 lbs to right at 127 lbs. So my biggest find was after I pulled the t-stat this engine ran very cool, barely ever over 110 degrees, which it seemed to like. Snow is starting to show up here so hopefully will be on it in the next 2 to 3 weeks and will know more.

Jkinzer · Oct 14, 2014

wfieldin said:
Many variables to this question:

Elevation, domes, fuel, BD box settings, clutching etc...??

I have one that has/had the higher comp domes 15:1, it would DET at certain times when in the flats. I found that it is very heat sensitive as well. Once I removed the t-stat I did not have any DET issues but it was at the end of last season and I was riding at higher elevations too (10000+). I was running 1 gal 112 to 4 gal 91. Kelsey cut me some 14:1 domes which I have installed but not run yet, I would like be able to run straight 91, we will see. I expect that I will have to play with my BD box numbers but hopefully not too much. Static compression in Denver with 15:1 domes was at 137 lbs, 14:1 lowered 10 lbs to right at 127 lbs. So my biggest find was after I pulled the t-stat this engine ran very cool, barely ever over 110 degrees, which it seemed to like. Snow is starting to show up here so hopefully will be on it in the next 2 to 3 weeks and will know more.

The "det" issue 99% of the time is the motor not being loaded hard enough and over revving causing a false detonation code to be thrown on the computer. this can be solved by running heavier weights, adjustable weights are nice because they allow you to load the heel super heavy which is what this torquey big bore craves.

I'm having a hard time understanding your compression on your sled with the two different dome sets? All of the kits that we have done (8 in house so far) were 13.5:1 domes and all had between 146-149 psi compression running straight 91 pump gas at 2500-8k feet. Do you have a Rev 1 kit maybe? all of my testing has been done on 13's and 14's but we havent seen any cooling issues at all with the billet head, it will run 125-130 all day long which is right where the motor was designed to run.

The 858 kit has exceeded mine as well as my customers expectations, reliability has proven to be every bit if not more reliable than stock. When mapped and clutched right it is super torquey on the bottom end and in the mid range and the top end seems to pull and pull. 8500 rpm's has never sounded so good. I would highly recommend a 3" track to get that power to the snow though as it will spin the stock track and dig some pretty big trenches.

Have quite a few videos on my youtube channel from one of our shop build 858's last year

SPS YouTube Channel

edavis0202 · Oct 14, 2014

I had one last year and it was a blast to ride. When the snow is kinda setup and a turbo is over kill its a blast in the trees.

I would recommend the 858 over any other BB for price vs HP. 3k gets you a awesome engine and depending on where you live a few shops have these things dialed for your area. I had the chance to compare it to the carls 900 and its not as snappy on the bottom but out pulls by a bit.

I think you would be very happy for a couple seasons with this engine.

good luck!

wfieldin · Oct 14, 2014

Jkinzer said:
The "det" issue 99% of the time is the motor not being loaded hard enough and over revving causing a false detonation code to be thrown on the computer. this can be solved by running heavier weights, adjustable weights are nice because they allow you to load the heel super heavy which is what this torquey big bore craves.

I'm having a hard time understanding your compression on your sled with the two different dome sets? All of the kits that we have done (8 in house so far) were 13.5:1 domes and all had between 146-149 psi compression running straight 91 pump gas at 2500-8k feet. Do you have a Rev 1 kit maybe? all of my testing has been done on 13's and 14's but we havent seen any cooling issues at all with the billet head, it will run 125-130 all day long which is right where the motor was designed to run.

The 858 kit has exceeded mine as well as my customers expectations, reliability has proven to be every bit if not more reliable than stock. When mapped and clutched right it is super torquey on the bottom end and in the mid range and the top end seems to pull and pull. 8500 rpm's has never sounded so good. I would highly recommend a 3" track to get that power to the snow though as it will spin the stock track and dig some pretty big trenches.

Have quite a few videos on my youtube channel from one of our shop build 858's last year

SPS YouTube Channel

Mine would DET at around 6800 plus or minus 200 rpm, so I don't feel it was an over revving issue. I ride mainly above 9000 feet. I have a REV 2 with rooster weights set up by VOHK. Yes the domes are what I stated according to Kelsey 15:1 is what I bought it with and he cut me 14:1 late last spring. I did not say I had cooling issues I stated that it ran very cool without the stat and I never DET once with it removed, but I was riding higher elevations that late in the season, and in spring like temps it still ran cool. I've never found two compression gauges to read the same, I use a nice older Snap-On, engine was cold, throttle wide open, mile high in Denver, that's all I can say about that.

Seabass152 · Oct 14, 2014

wfieldin said:
Mine would DET at around 6800 plus or minus 200 rpm, so I don't feel it was an over revving issue. I ride mainly above 9000 feet. I have a REV 2 with rooster weights set up by VOHK. Yes the domes are what I stated according to Kelsey 15:1 is what I bought it with and he cut me 14:1 late last spring. I did not say I had cooling issues I stated that it ran very cool without the stat and I never DET once with it removed, but I was riding higher elevations that late in the season, and in spring like temps it still ran cool. I've never found two compression gauges to read the same, I use a nice older Snap-On, engine was cold, throttle wide open, mile high in Denver, that's all I can say about that.

Kinzer is right about the DET. Load it more and the mid rpm det goes away. I went through the same thing. It also feels meatier with the added weight. Mine was the worse when I would let off and then stab back into the throttle at around 7k.

wfieldin · Oct 14, 2014

weight

Seabass152 said:
Kinzer is right about the DET. Load it more and the mid rpm det goes away. I went through the same thing. It also feels meatier with the added weight. Mine was the worse when I would let off and then stab back into the throttle at around 7k.

what weight setup are you using and what elevation you running?

Seabass152 · Oct 14, 2014

wfieldin said:
what weight setup are you using and what elevation you running?

I do not have the 858 kit, just have experienced the same issue. Sled is a 12 155 with PAR 13.6 head, PC fueler w/slp stg 2 & 3 map, SLP full pipe, more air, power claw track. carls helix with bright green primary

MTX weight at 71g(Same as a 10-67) to run about 8100 at my usual Tahoe riding area 6500-9000ft. Weights are 68 w/3 in the heel.

Steamboat(7500-10500ft) I run EPI 64's

Summit County Co 10-62 or 63
Anything less than the 71 MTX's at home and I would get that mid throttle DET come up.

Also for reference, my compression with the 13.6 head is 127 at 6000ft at 500 miles. Only checked with my econo gauge and only at 500 miles.

Hope it helps

Jkinzer · Oct 15, 2014

Seabass152 said:
I do not have the 858 kit, just have experienced the same issue. Sled is a 12 155 with PAR 13.6 head, PC fueler w/slp stg 2 & 3 map, SLP full pipe, more air, power claw track. carls helix with bright green primary

MTX weight at 71g(Same as a 10-67) to run about 8100 at my usual Tahoe riding area 6500-9000ft. Weights are 68 w/3 in the heel.

Steamboat(7500-10500ft) I run EPI 64's

Summit County Co 10-62 or 63
Anything less than the 71 MTX's at home and I would get that mid throttle DET come up.

Also for reference, my compression with the 13.6 head is 127 at 6000ft at 500 miles. Only checked with my econo gauge and only at 500 miles.

Hope it helps

Jealous of the elevation difference but that would make since on the compression tests as my shop is only at 1000 feet elevation, kind of neat to see the elevation difference effect.

McKayMarine · Oct 15, 2014

It was my buddy's sled that had all the det issues last year that I'm sure you read about, it drove him nuts and lost the whole season. Luckily he had a back up sled. The problem ended up being the wrong domes being shipped.
Mistakes happen and RK Tek helped out on the repair at the dealer.

I have the 858 along with another buddy and they work perfect and are a big difference over stock.

You should have ordered one in the summer cause they get busy this time of year.

Shobiz6 · Oct 15, 2014

Here's a newb question too if I got this kit could I run my dobeck fuel controller on it I think it's a 2013 box I used on a turbo but won't need for that this year. Or do you need to use the boondocker??

die hard poo · Oct 15, 2014

The dobeck is designed for a turbo application, so it probably controlled aux injectors and not the stock injectors. You would need a controller that can manipulate the stock injectors. Dobeck does sell a box that does this, but I would recommend getting a PCV or boondocker just so you can get some sort of baseline map from RK or someone like SPS.

RFleck17105 · Oct 28, 2014

What domes and clutch weight for 9,000 ft and up? Just curious if I should go turbo or will the 858 run well at 9,000 ft +.

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Rk Tek 858

Shobiz6

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die hard poo

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wfieldin

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Jkinzer

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edavis0202

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wfieldin

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Seabass152

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wfieldin

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Jkinzer

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Shobiz6

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