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Shovel and evo full advance is 36 — our big block nova super gas car we add 2 degrees timing new engine each pass till it slows down in the cars ET
then back off 1 degree at a time till hopefully freezes in the ET - super gas is 9:90 so in all weather you need a 9:20 car to cover it
timing a weight is used to zero in on a number
and you do not need special gas with under 11 to 1 compression — tune it to the gas you can buy local at any station is the real deal - timing is the deal to get you in the right spot - 3 threads down 100 mile spark plugs is the correct heat range and a brown color is the right mixture - i have never used a tee or what ever its called to tune
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I actually found more mph pulling timing from my shovel. Mechanically it’s 11.7:1 and my favorite cam in it was the Andrew’s M grind. My timing was usually around 28 to 30, much more than that and it was too hot on the street, I risked detonation. With 100 octane and a cooler set of plugs I could stay in the 30 and run a bit rich. There were and are always compromises. Bike consistently ran mid to high 11’s with a 130 street tire, no shift assistance, and often pump gas.
While I’ve assembled and built two 127’s now I have little experience tuning anything this big. All new to me. So I appreciate the advice you folks share.
I think I’ve got the jetting pretty close now, the timing is just static at about 30-31. I’m running a 32/84. I might try a bigger air bleed and go 31/88..but that can wait till it’s broke in and I can play at the track. I also tried a new trick of marking the stator housing and inner primary to time from there.. we’ll see.
Last edited by Rains2much; Oct 28, 2023 at 05:37 PM.
The big thing with AFRs is that big evo motors run hot.. A little extra fuel can help cool the motor.. You can go pretty lean and still make good power but the heat goes up. Air cooling on Evos ain that good. I've got a mouse SnS 113 and it still pretty skimpy on the fins compared to a Twincam..
While pulling timing can loose power so can too much.. I'm running only 27 deg full advance and it don't hit full until 5000.
I wonder about your "pulling back timing richens .1 afr to every 1 degree" with EFI. If closed loop, does the efi add or remove fuel?
Did alot of street tuning time with a 10.2-1 89" Evo, 42 intake closing cam still running the M&M efi system. M&M follows a programmed map with no O2 sensors, it's not a very smart system. The Wego system I have has the ablilty to create fuel maps in a Powercommander format, roll on area was a problem, decreased timing 1 degree at a time in problem area only, running it again, the afr's in the cells timing was removed changed .1 degree richer, adding 1 degree timing which created more detonation recording .1 afr leaner.
Rains2much how much compression are you running on the 127?
Did alot of street tuning time with a 10.2-1 89" Evo, 42 intake closing cam still running the M&M efi system. M&M follows a programmed map with no O2 sensors, it's not a very smart system. The Wego system I have has the ablilty to create fuel maps in a Powercommander format, roll on area was a problem, decreased timing 1 degree at a time in problem area only, running it again, the afr's in the cells timing was removed changed .1 degree richer, adding 1 degree timing which created more detonation recording .1 afr leaner.
Rains2much how much compression are you running on the 127?
I actually found more mph pulling timing from my shovel. Mechanically it’s 11.7:1 and my favorite cam in it was the Andrew’s M grind. My timing was usually around 28 to 30, much more than that and it was too hot on the street, I risked detonation. With 100 octane and a cooler set of plugs I could stay in the 30 and run a bit rich. There were and are always compromises. Bike consistently ran mid to high 11’s with a 130 street tire, no shift assistance, and often pump gas.
While I’ve assembled and built two 127’s now I have little experience tuning anything this big. All new to me. So I appreciate the advice you folks share.
I think I’ve got the jetting pretty close now, the timing is just static at about 30-31. I’m running a 32/84. I might try a bigger air bleed and go 31/88..but that can wait till it’s broke in and I can play at the track. I also tried a new trick of marking the stator housing and inner primary to time from there.. we’ll see.
I think you got the air bleed thing backwards... If you go to a larger air bleed atmospheric on the bowl will change which will make the main jet come in later.. So if you put a larger air bleed in which will make the main jet come in later you'll need to run more on the intermediate jet, not go down but actually go up in size because you're going to stretch that out further In the RPM range.. I've seen that with my Wego III..
Personally I would just make sure I put the proper size intermediate jet in for low end drivability and then see how far that jet takes you into the rpms before starting to go lean for your liking..
With my Wego III I'll take the intermediate jet to 13.8@3000 rpm Max and then would adjust my air bleed so the main starts to add to without going to rich to soon.. on S&S carb 0.040" external air bleed will allow the main to start to come in at 2850 rpm. I'm currently using a jet I drilled out to .047" and I'm not to rich at 3100rpm.. I like to see 13.4-13.5 by 4000 rpm... And 13.1 by 5000 and 12.8 by 5500.. I also run a thunder jet which allows me to run a smaller main and not over richen the transition from intermediate to main..
Last edited by 98hotrodfatboy; Oct 30, 2023 at 06:49 PM.
I think you got the air bleed thing backwards... If you go to a larger air bleed atmospheric on the bowl will change which will make the main jet come in later.. So if you put a larger air bleed in which will make the main jet come in later you'll need to run more on the intermediate jet, not go down but actually go up in size because you're going to stretch that out further In the RPM range.. I've seen that with my Wego III..
Personally I would just make sure I put the proper size intermediate jet in for low end drivability and then see how far that jet takes you into the rpms before starting to go lean for your liking..
With my Wego III I'll take the intermediate jet to 13.8@3000 rpm Max and then would adjust my air bleed so the main starts to add to without going to rich to soon.. on S&S carb 0.040" external air bleed will allow the main to start to come in at 2850 rpm. I'm currently using a jet I drilled out to .047" and I'm not to rich at 3100rpm.. I like to see 13.4-13.5 by 4000 rpm... And 13.1 by 5000 and 12.8 by 5500.. I also run a thunder jet which allows me to run a smaller main and not over richen the transition from intermediate to main..
Were on the same page. I’d like to move up the bleed so it’s less rich at the transition and see where that gets me. If it doesn’t work then I’ll be tempted to go leaner intermediate and I dont think that’s what it wants. I’m 1 .5 to 7/8 out on the mix screw indicating I might need Richer, but with a 33 it’s turned in to about a half out and it gets sluggish. It’s kinda between a 32 and a 33. I can go smaller Main as well but it feels right on top, hence taking some out at the transition. Other than the popping.. it feels good right where it is.
I’ll check the float again when I get a chance just to be sure I’m not masking a lean or rich condition
Last edited by Rains2much; Oct 31, 2023 at 03:12 PM.
So you're running a 0.032 at 1 and 7/8 turnout on the mixture screw, is that correct? If that is the case I would leave the 32 and then start with your air bleeds to bring your main in so your AFRs don't go too lean by the time your intermediate jet is running out. Do you have anything to monitor the air fuel ratios with? And trust me if you take out that third jet "the Thunderjet" you're going to have to run a bigger main to carry you up through the higher RPMs and when you do that, that's when the transition point from intermediate to msin is going to be really fat giving you stumbles and whatnot. This is what makes the ThunderJet so valuable..
So you're running a 0.032 at 1 and 7/8 turnout on the mixture screw, is that correct? If that is the case I would leave the 32 and then start with your air bleeds to bring your main in so your AFRs don't go too lean by the time your intermediate jet is running out. Do you have anything to monitor the air fuel ratios with? And trust me if you take out that third jet "the Thunderjet" you're going to have to run a bigger main to carry you up through the higher RPMs and when you do that, that's when the transition point from intermediate to msin is going to be really fat giving you stumbles and whatnot. This is what makes the ThunderJet so valuable..
Sorry if Ive left the wrong impression. This is a bored out G with an adjustable air bleed and no t-jet. You may be thinking from another thread where I mention I have a D that has T-Jets and I would like to remove them and try the D down the road to see if more power is there.
For now with the G bored out shaved throttle shaft, adjustable air bleed Im running 32/84 and a 120 air bleed. Currently when the motors nice and warmed up around 200 degrees oil, the mix screw is between 1.5 and 1 7/8 out. With a 33 it was like half a turn out meaning 32 is probably right.
Personally I don't care how many turns out the pilot adjustment is when setting the idle mixture. I use the int jet to get the motor running its best with the smallest jet possible from idle to about 1/8 throttle.. Use main jet air bleed and main jet to get from there to WOT up to about 5K. Tjet beyond that.
I'm currently running a 31 int jet in my 113. 78 main, 120 keihin air bleed, 160 keihin Tjet, 0.062 cross drilled Tjet air bleed.
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