ghost rider
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So my experience with a AFR is only on automobiles... Ones that run sophisticated ecu
That will read the AFR and constantly adjust the air, fuel, boost, timing and injector pulses
To always maintain an optimum AFR ....... Now on a carbureted sled it's up to me, the user,
To obtain the same results or risk blowing the engine or running pig rich.
Hear we go .... Idle is at 14.5 to 15.4
Cruise-no boost 13.5
Full boost 10.0 - with sputtering @ 9-10lbs boost.
I'm taking out fuel pressure 1 full turn at a time to ideally hit 11.2-11.5
At wot..... This is what my turbo guy tells me to do at 10.0 it's pig rich
Obviously bad.... Now I'm not sure how much fuel pressure I can take out of the regulator
Currently I have about 3/8" of threads above the base and I'm worried I have raised the
Plunger to its limits.
I'm running stock jets... New plugs... Boost @ 8-10 and 110 octane fuel.
Now ... How far can playing with the fuel preasure go?
Do I need to re jet? Or should I keep turning down the fuel pressure until I get the AFR that I need to stop the sputtering ?
As I turn down the preasure, It's now Idling beautifully and revs very fast and clean ....Just the wot sputter and 10.0 AFR
Any ideas?
Thanks,
Barry
That will read the AFR and constantly adjust the air, fuel, boost, timing and injector pulses
To always maintain an optimum AFR ....... Now on a carbureted sled it's up to me, the user,
To obtain the same results or risk blowing the engine or running pig rich.
Hear we go .... Idle is at 14.5 to 15.4
Cruise-no boost 13.5
Full boost 10.0 - with sputtering @ 9-10lbs boost.
I'm taking out fuel pressure 1 full turn at a time to ideally hit 11.2-11.5
At wot..... This is what my turbo guy tells me to do at 10.0 it's pig rich
Obviously bad.... Now I'm not sure how much fuel pressure I can take out of the regulator
Currently I have about 3/8" of threads above the base and I'm worried I have raised the
Plunger to its limits.
I'm running stock jets... New plugs... Boost @ 8-10 and 110 octane fuel.
Now ... How far can playing with the fuel preasure go?
Do I need to re jet? Or should I keep turning down the fuel pressure until I get the AFR that I need to stop the sputtering ?
As I turn down the preasure, It's now Idling beautifully and revs very fast and clean ....Just the wot sputter and 10.0 AFR
Any ideas?
Thanks,
Barry
mbarryracing
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Barry,
What is your base fuel pressure set at now? I recall with carbs that we had set the base FP around 6 psi so we weren't leaking past the needles and flooding. The regualtor will raise the fuel pressure 1:1 with boost so the needles will always see 6 psi fuel pressure differential and therefore fuel will always flow and fill the float bowls as quickly as possible. When you run lower FP then they won't fill as fast.
Not sure how much you are lowering the FP, and that is a way to change AFR, but I think the safer way is to change the mains to correct your AFR at WOT. 10:1 AFR is gonna cause sputtering, my Apex with FI does it. In fact this past weekend when I was running ethanol free premium in the Old Forge it lowered my AFR by 1 point and was seeing 10:1 at WOT and it would hick-up every now and then...
Mauri
What is your base fuel pressure set at now? I recall with carbs that we had set the base FP around 6 psi so we weren't leaking past the needles and flooding. The regualtor will raise the fuel pressure 1:1 with boost so the needles will always see 6 psi fuel pressure differential and therefore fuel will always flow and fill the float bowls as quickly as possible. When you run lower FP then they won't fill as fast.
Not sure how much you are lowering the FP, and that is a way to change AFR, but I think the safer way is to change the mains to correct your AFR at WOT. 10:1 AFR is gonna cause sputtering, my Apex with FI does it. In fact this past weekend when I was running ethanol free premium in the Old Forge it lowered my AFR by 1 point and was seeing 10:1 at WOT and it would hick-up every now and then...
Mauri
wantboost
Expert
Barry do not tune your wot afr with turning fp down unless the fp is set to high to start with.idle fp I believe is around 4lbs so that should be your base set up.10afr is way rich shoot for about 11.5 to 11.8 I dont know why it would be so rich with stock jetting, you know for sure that its stk jetting including needle position?
ghost rider
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Thanks for your insights guys . I also felt that AFR tuning should not be done by fp alone.
I don't know my actual fp - need to get a gauge. I also don't know where my needles are set
But I know the jets are stock as I installed the turbo on the sled.
Would adjusting the needles help at all or should I go with re-jetting?...
Again that's for your input.... It really helps me to sort this out.
Barry
I don't know my actual fp - need to get a gauge. I also don't know where my needles are set
But I know the jets are stock as I installed the turbo on the sled.
Would adjusting the needles help at all or should I go with re-jetting?...
Again that's for your input.... It really helps me to sort this out.
Barry
ghost rider
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I have a fuel gauge and a truck load of jets on loan from the modfather
I will start with 132.5 and see where it sits.... The curve is excellent it's only WOT that I need to raise from 10.0 to 11.8.
I will start with 132.5 and see where it sits.... The curve is excellent it's only WOT that I need to raise from 10.0 to 11.8.
Barry, is this the sled that you met me in Michigan and traded your sled on?
Not the same Barry 
ghost rider
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rxwarrior said:
No sorry wrong guy, I've never snowmobiled out side of canada.... Yet.
Pm'd you Dennis (Barry)
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We R running 127.5 main jets at 300 - 1300 feet elevation on a 11 ish PSI MPI Supercharged RX 1.
A lot of the Turbo RX 1 guys ran 130 or a little lower mains in the day.
I think you can skip the 1.325's and go to 127.5's to start from my experience, your AFR #'s and all I have read if your elevation is similar to ours.
rxrider runs 127.5's as well in his Turbo RX 1.
RX 1's like to be fat but not that fat.
A lot of the Turbo RX 1 guys ran 130 or a little lower mains in the day.
I think you can skip the 1.325's and go to 127.5's to start from my experience, your AFR #'s and all I have read if your elevation is similar to ours.
rxrider runs 127.5's as well in his Turbo RX 1.
RX 1's like to be fat but not that fat.
ghost rider
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Riceburner said:
Thanks for the help riceburner... I have a jet kit that has 130 or 125... I'm waiting on 127.5
They're on order but will take a week to get hear.... Do you think I should try the 130's
or wait for the 127.5's
We are 1040 ft above sea level.
Barry
rxrider
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ghost - what is Your fuel pressure.
Should be around 4.5 at idle but between 4-5 is ok.
If Your fuel pressure is Close, then work on the main jets. I ride at similar altitude, from 0-2000 ft. I run 127.5 mains. I'm lean on a Cold day below -10C, but OK from +5C to -10C. At -5 my AFR's are bang on around 12 AFRs. Running 22 lbs of boost spraying water/alcohol.
Should be around 4.5 at idle but between 4-5 is ok.
If Your fuel pressure is Close, then work on the main jets. I ride at similar altitude, from 0-2000 ft. I run 127.5 mains. I'm lean on a Cold day below -10C, but OK from +5C to -10C. At -5 my AFR's are bang on around 12 AFRs. Running 22 lbs of boost spraying water/alcohol.
ghost rider
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Fuel pressure us at 4.5 as you suggested... I had a bad coil so I replaced all of them.
Going for a test ride tomorrow and see where I sit with AFR ....I will try the 127.5 mains
But it is a pain to change them this late in the season... I will see if I sputter and if not
I will ride out this winter and change the mains over the summer when my garage is not at -25c
22lbs.... Must be a mind warp with that kind of power......
Barry
Going for a test ride tomorrow and see where I sit with AFR ....I will try the 127.5 mains
But it is a pain to change them this late in the season... I will see if I sputter and if not
I will ride out this winter and change the mains over the summer when my garage is not at -25c
22lbs.... Must be a mind warp with that kind of power......
Barry
rxrider
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Yes sir
ghost rider
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Up date..,, today the sled runs fine trough the trails for the first hour
No drama but also not pushing it too hard,
On the return take the lake route and give it wot and again sputter and shut down
AFR reading 10.0-10.4 wot... Now if I eas into the throttle it's fine.. But I need to creep it to wot very very slowly....odd.
Also once on the trail it kept running rich during cruise at 7 k rpm 3lbs boost light throttle
AFR at 12.7-13.4 the AFR goes crazy and the engine makes a brrrrrup noise like it has lost all
Power and ignition/ compression... Then sputter... Stall. This was off and on all the way home.
Now when it's on it hauls great.... Put in new coils plugs and 130 mains 4.5 lbs fuel pressure.. Starting to suspect the fuel preasure regulator ....maybe it keeps progressively adding pressure beyond boost... Or it's just f&&ed... I'm lost.....any ideas???????
Barry
No drama but also not pushing it too hard,
On the return take the lake route and give it wot and again sputter and shut down
AFR reading 10.0-10.4 wot... Now if I eas into the throttle it's fine.. But I need to creep it to wot very very slowly....odd.
Also once on the trail it kept running rich during cruise at 7 k rpm 3lbs boost light throttle
AFR at 12.7-13.4 the AFR goes crazy and the engine makes a brrrrrup noise like it has lost all
Power and ignition/ compression... Then sputter... Stall. This was off and on all the way home.
Now when it's on it hauls great.... Put in new coils plugs and 130 mains 4.5 lbs fuel pressure.. Starting to suspect the fuel preasure regulator ....maybe it keeps progressively adding pressure beyond boost... Or it's just f&&ed... I'm lost.....any ideas???????
Barry
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