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RK 858 fuel numbers

R
Jan 20, 2014
33
4
8
52
Hello Powerage

I understand from your previous post you are at 1200 Ft.

Can you please tell me what you are running for fuel octane?

Can you also please tell me what domes you have on your RKT 858 Big Bore

Please and Thank You

Scott
 
P
Dec 3, 2007
85
22
8
12.5 domes. 91 non Ethanol pump gas. Those numbers have been adjusted a little from my first post. They are almost exactly what kelsey recommends now. Somewhere between 100-130 miles this engine woke up and i had to throw more weight at it and add a couple numbers in the fuel department. My map looks like kelseys with a little added fuel in the 4000-5500 range. I did have a random top end bog and i actually caught the engine light on once. Check it and i had a bad exhaust probe that was adding 10% fuel. So with the fuel controller i was crazy rich. Seems to run pretty good where i have it now. Have somewhere around 73-74 grams in it and i think it could use .5-1 gram more. Using rooster weights. 150-340 spring.
 
P
Dec 3, 2007
85
22
8
Here is my fuel numbers running 91 NON ETH pump gas at 1200FT. I have 9 grams heel 5.6 mid and 3.5 tip on rooster weights. Total weight of 74.1 grams. Running a 150-340 (bright green) primary spring. Secondary is Team tied with a 140-200 spring (red/blue) and a 73-61 .46 helix. Gearing is at 19 top and 45 bottom. This setup is working very very good. I am hitting the rev limit every once in a while. I think i am going to add .5 gram more to the tip and see how it works. Snow is very light and it's cold here. Warm day in heavy snow i don't think it would need the extra weight. Hope this helps some of the lower elevation guys out.

EDIT** Clutches are very very cool with this setup also.


2500: 00 00 00 00 00 00
4000: 02 02 02 03 03 03
5000: 03 03 03 04 04 04
5500: 04 04 04 05 05 06
6000: 07 07 08 09 09 09
6500: 08 08 10 11 11 11
6750: 08 08 10 11 11 11
7000: 10 12 12 13 14 14
7250: 09 11 12 15 15 15
7500: 09 11 12 16 16 16
7750: 08 10 11 17 17 17
8000: 10 12 12 18 18 18
8500: 11 13 14 18 18 18
 
R
Jan 20, 2014
33
4
8
52
Thank you very very very much.

I forgot to ask if you are running the stock pipe and stock can or something different??

Please let me know and Thank You Again!!!

-Scott
 
P
Dec 3, 2007
85
22
8
Did 120 miles yesterday and tuned most of the way. It is running very very good at these #'s. Rode 800-1500 feet. Below 1000 i was still hitting rev limiter with 74 grams in. Even a couple times above 1000. Gonna try add some more weight yet i guess. The more i drive this engine the more power it seems to make!! I still think these numbers are a little rich on the top end. Next ride i am going to pull a couple more numbers out from 7500 and up. Right now it's running 11.4-11.7 AFR above 7500. The rev limiter needs to be disabled with this engine below 2500 ft i think. It just revs so fast and high that it trips it a lot unless the engine is very loaded. A couple minor inssues that never really bothered me during the 120 mile ride yesterday. About 300 miles on it now.


2500: 00 00 00 00 00 00
4000: 03 03 03 03 03 03
5000: 04 04 04 04 04 04
5500: 04 04 04 04 04 04
6000: 10 10 10 10 10 10
6500: 10 10 10 11 11 11
6750: 08 08 10 13 13 13
7000: 10 12 12 13 13 14
7250: 09 11 12 13 14 14
7500: 09 11 12 14 14 14
7750: 08 10 11 13 13 13
8000: 10 12 12 16 15 15
8500: 11 13 14 17 17 17
 

Sunvang

Well-known member
Lifetime Membership
Dec 4, 2010
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Did 120 miles yesterday and tuned most of the way. It is running very very good at these #'s. Rode 800-1500 feet. Below 1000 i was still hitting rev limiter with 74 grams in. Even a couple times above 1000. Gonna try add some more weight yet i guess. The more i drive this engine the more power it seems to make!! I still think these numbers are a little rich on the top end. Next ride i am going to pull a couple more numbers out from 7500 and up. Right now it's running 11.4-11.7 AFR above 7500. The rev limiter needs to be disabled with this engine below 2500 ft i think. It just revs so fast and high that it trips it a lot unless the engine is very loaded. A couple minor inssues that never really bothered me during the 120 mile ride yesterday. About 300 miles on it now.


2500: 00 00 00 00 00 00
4000: 03 03 03 03 03 03
5000: 04 04 04 04 04 04
5500: 04 04 04 04 04 04
6000: 10 10 10 10 10 10
6500: 10 10 10 11 11 11
6750: 08 08 10 13 13 13
7000: 10 12 12 13 13 14
7250: 09 11 12 13 14 14
7500: 09 11 12 14 14 14
7750: 08 10 11 13 13 13
8000: 10 12 12 16 15 15
8500: 11 13 14 17 17 17

Lifting this thread again.

I tried out most of you numbers, but it seems to run a little rich. What a/f ratio do you have with these numbers?

When my exhaust valves open i see a a/f ratio drop from 13.5-14.5 down to 11.5-12.5. It stays at that same ratio all the way from around 5500-6000 to 8400 WOT.

It stutters alittle on low rpms, and i have got some bogging, but nothing consistent, and only 2-3 times.
 
V
Nov 26, 2007
193
19
18
Seems like you are adding too much fuel in the lower throttle positions. I know the PCV is a bit different, but the maps I use from Jim at Dynotech work well and we don't add much fuel until we get to the 80% TP. I add some at the 60% and nothing in the lowers at all.
 

Sunvang

Well-known member
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Dec 4, 2010
1,043
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Norway
Seems like you are adding too much fuel in the lower throttle positions. I know the PCV is a bit different, but the maps I use from Jim at Dynotech work well and we don't add much fuel until we get to the 80% TP. I add some at the 60% and nothing in the lowers at all.


What a/f numbers are you seeing?


Sent from my iPhone using Tapatalk
 
V
Nov 26, 2007
193
19
18
What a/f numbers are you seeing?


Sent from my iPhone using Tapatalk

Sorry, no AFR on my sled. I can tell you from experience the mid fueling is plenty rich, especially on the 13's and 14's. ON HCS there is a guy trying to get his RTK sled to run with a map very similar to what is shown here and it doesn't work. Trying to tune with afr at part throttle is really tough.
 

Sunvang

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Dec 4, 2010
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Sorry, no AFR on my sled. I can tell you from experience the mid fueling is plenty rich, especially on the 13's and 14's. ON HCS there is a guy trying to get his RTK sled to run with a map very similar to what is shown here and it doesn't work. Trying to tune with afr at part throttle is really tough.

Took the sled out today, running well after I leaned it out on the lower rpms and throttle positions. Now i need to get the clutching straight.

Im running Cutlers TM series with a base weight of 65. Even with them empty I cant get it to hold the rpms high enough, and I run 10-68 polaris weights stock.
 
G

geo

Well-known member
Dec 1, 2007
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Kamloops B.C.
What do you consider is the mid fueling area? Throttle position, rpm.
Is this with stock reeds?

Elevation you ride should be included if giving advice. Most of the quality aftermarket suppliers for Pro engine supply at least 3 very different maps.
 

Sunvang

Well-known member
Lifetime Membership
Dec 4, 2010
1,043
379
83
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Norway
What do you consider is the mid fueling area? Throttle position, rpm.
Is this with stock reeds?

Elevation you ride should be included if giving advice. Most of the quality aftermarket suppliers for Pro engine supply at least 3 very different maps.

Mid fuel area is from 5000-7000. Throttle position is typical trail rding, all from 10% to 50%. Not stock reeds, V-Force 3R.

Elevation is 1500 to 4000ft.
 
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