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Daniel McBride
Joined: 30 Jun 2012
Posts: 5
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 Posted: Mon Feb 11, 2013 11:54 am Post subject: Leopard Tuning Newbie Questions (Help!) |
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Preface: I'm a total novice when it comes to tuning the leopard carb. I know this is a long post, but I'd really appreciate any help ya'll could provide. Thanks!
In preparing to run my kart, I called the local shop and asked what they ran for leopard carb settings, to which they responded 1.5 T.O. on L and 1.0 on H. I used those settings for my first test, and saw what I thought were low EGTs and a lot of blowby (I've been told that a little is normal for the leopard, but not to the degree where the shoulders of your suit are covered with a litany of black oil spots).
So, today I tried to tune the kart according to the IAME manual (http://www.tagaustralia.com.au/downloads/leopard_manual.pdf, p. 22) , and ended up stopping when the engine reached max idle RPMs like the manual said, and the L screw was just below 3/4 T.O. Granted, I live in Houston, and today was raining (100% humidity), so a leaner mixture might have been appropriate, but half of what the shop said seems way off. The engine seemed happy at 3/4 T.O., but I don't want to run it and damage it by running to lean. At that setting, the idle screw was backed almost completely off the throttle lever.
Do any of those settings sound weird to you?
Does it matter that the engine was (likely) built in Arizona (Dry) and now are in Houston (Humid)?
Is there an idle EGT that I should be shooting for?
How should I tune the high speed setting?
Thanks again, really appreciate the help. 
Daniel |
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Greg Wright
Joined: 25 Oct 2001
Posts: 2495
Location: United States, Indiana, Clermont
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| Posted: Mon Feb 11, 2013 1:00 pm Post subject: |
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Those setting sound very weird. Air quality, altitude etc. make a difference but in my experience the settings are typically;
Low 1 3/4-2 turns out
High 3/4-1 turn out
There could be a carb problem haunting you.
DO NOT RUN THE ENGINE WITH 3/4 TURN ON THE LOW SIDE!!
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Greg Wright
Rapid Racing Inc.
NKN Columnist & Host "Karting News Live"
I AM INDY!!
"When in doubt, gas it. It won't help but it ends the suspense." |
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TJ Koyen
Joined: 03 Oct 2004
Posts: 1413
Location: United States, Wisconsin, Sun Prairie
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| Posted: Mon Feb 11, 2013 1:18 pm Post subject: |
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| Greg Wright wrote: | Those setting sound very weird. Air quality, altitude etc. make a difference but in my experience the settings are typically;
Low 1 3/4-2 turns out
High 3/4-1 turn out
There could be a carb problem haunting you.
DO NOT RUN THE ENGINE WITH 3/4 TURN ON THE LOW SIDE!! |
I second Greg's recommended settings. Those are good starting settings. Peak EGT we usually shoot for is 1020.
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T.J. Koyen
OKTANE VISUAL - Custom Helmet Paint & Graphic Design
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Dan Haynes
Joined: 17 Sep 2007
Posts: 2371
Location: United States, Pennsylvania, Ellwood City
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| Posted: Mon Feb 11, 2013 2:36 pm Post subject: |
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Same as TJ, we shoot for about 1020.
BTW-the Leopard will not idle with the carb set to race settings. And I wouldn't worry about the idle screw. It won't be doing anything anyway.
If it will idle the your low speed is too lean. 3/4 is good for idling on the stand. I can't remember off the top of my head what we use as a starting point for our settings (we haven't raced since last May) but I know it isn't 3/4 on the low.
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Blaise Haynes
#3 Arrow X1-CIK
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Cook Racing Engines Parilla Leopard |
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TJ Koyen
Joined: 03 Oct 2004
Posts: 1413
Location: United States, Wisconsin, Sun Prairie
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| Posted: Mon Feb 11, 2013 2:41 pm Post subject: |
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How high did you rev it on the test run you did that you saw the low EGT numbers on?
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T.J. Koyen
OKTANE VISUAL - Custom Helmet Paint & Graphic Design
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www.facebook.com/oktanevisual
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Daniel McBride
Joined: 30 Jun 2012
Posts: 5
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| Posted: Mon Feb 11, 2013 6:54 pm Post subject: |
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| Greg Wright wrote: | Those setting sound very weird. Air quality, altitude etc. make a difference but in my experience the settings are typically;
Low 1 3/4-2 turns out
High 3/4-1 turn out
There could be a carb problem haunting you.
DO NOT RUN THE ENGINE WITH 3/4 TURN ON THE LOW SIDE!! |
Any specific carb problem you're thinking of in general?
TJ, I saw ~530 and probably got to 10k (not on a kart track, very short run area). Does that sound rich, right, or lean?
Thanks!
Daniel |
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Dan Haynes
Joined: 17 Sep 2007
Posts: 2371
Location: United States, Pennsylvania, Ellwood City
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| Posted: Mon Feb 11, 2013 8:27 pm Post subject: |
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You won't get a good EGT reading at 10,000 RPM. In sprint racing we turn about 16,200-16,400. That low of RPM and you will be spitting oil out the exhaust. I think the road racers only rev theirs to about 14,000 but can't say for sure. Maybe they set their carbs differently. Don't know.
Also, make sure you have the water temp up to at least 100* F. We make sure to get ours to 110 before running it hard. That won't affect your EGT but will effect your piston and cylinder!
To get a little more temp try running your water pump bands directly off the axle with no pulley. That will slow down your water pump.
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Blaise Haynes
#3 Arrow X1-CIK
TaG
Cook Racing Engines Parilla Leopard |
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Greg Wright
Joined: 25 Oct 2001
Posts: 2495
Location: United States, Indiana, Clermont
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| Posted: Tue Feb 12, 2013 6:53 am Post subject: |
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| Daniel McBride wrote: |
Any specific carb problem you're thinking of in general?
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Leaking needle and seat, improper pop off, improper fulcrum arm height, misassembled pumper stack.
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Greg Wright
Rapid Racing Inc.
NKN Columnist & Host "Karting News Live"
I AM INDY!!
"When in doubt, gas it. It won't help but it ends the suspense." |
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TJ Koyen
Joined: 03 Oct 2004
Posts: 1413
Location: United States, Wisconsin, Sun Prairie
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| Posted: Tue Feb 12, 2013 7:16 am Post subject: |
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| Daniel McBride wrote: | | Greg Wright wrote: | Those setting sound very weird. Air quality, altitude etc. make a difference but in my experience the settings are typically;
Low 1 3/4-2 turns out
High 3/4-1 turn out
There could be a carb problem haunting you.
DO NOT RUN THE ENGINE WITH 3/4 TURN ON THE LOW SIDE!! |
Any specific carb problem you're thinking of in general?
TJ, I saw ~530 and probably got to 10k (not on a kart track, very short run area). Does that sound rich, right, or lean?
Thanks!
Daniel |
Like Dan said, sounds like you never got going fast enough to have the EGT come up. You won't see peak EGT until about peak RPM. And if you're driving around slowly you won't burn that fuel off.
It's a 2-stroke, it only likes to scream, not put around. 
I'd put the settings back to baseline of what was recommended to you and go at it again. We even get a lot of oil coming out sometimes when it's just a bit too rich so that's probably not a big deal.
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T.J. Koyen
OKTANE VISUAL - Custom Helmet Paint & Graphic Design
www.oktanevisual.com
www.facebook.com/oktanevisual
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al nunley
Joined: 13 Nov 2006
Posts: 3030
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| Posted: Tue Feb 12, 2013 8:00 am Post subject: |
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| Daniel McBride wrote: |
TJ, I saw ~530 and probably got to 10k (not on a kart track, very short run area). Does that sound rich, right, or lean?
Thanks!
Daniel |
EGT readings are a little harder to read than CHT.
You want the maximum reading you can get. (you can’t run in a parking lot and get any useful information)
Detonation Is caused by excessive heat and/or pressure. The fact that a 2cycle produces peak torque at the lower end of the RPM range, means it’s producing maximum pressure at the lower end, this means you have to get more fuel, (run richer) into the engine to prevent the detonation. This will give you lower EGT readings. At the top end, because the pipe and the engine are less efficient, the engine can run leaner and the EGT will read higher. You want the highest RGT reading you can get on both the low end and the top end. They will be different. Unlike the CHT, if you get a little lean, the EGT will go down. If, on one lap you see, just for demonstration, a number like 1150, on the top, and the next lap you see a number like 1075, or something in-between, first open the high speed, if it goes lower, then you were rich, if it goes higher, then you were lean. Always start off rich and then lean it down until you see that drop, (it drops way before the engine is going to stick) and then richen up till the reading is just below the peak. Same on the bottom end, if you see a reading, coming out of the tightest turn, that is lower than the previous lap, open the low speed and see if it goes up, if not, lean it down a “little”. it takes some practice, but at some point the readings, (unless you develop an engine problem) will stabilize.
EGT readings will change with air density, (air density changes very little with a change in humidity, or even with very high, or very low, readings.) so be aware of it. On a hot, low air density day, the readings will be lower, the carb settings will be leaner. But just because it’s hot doesn’t mean you will see low air density readings. It can be hot, (say low 80’s) and the barometric pressure can be high, and thus you will see high air density. Just the same for a cold day. This is why the air density gauge is so important.
So, with the air density readings in your head as you go out to race, you will be better able to understand the EGT readings you’ll see during the race.
“Very important”, don’t get it in your head that there is a “perfect” EGT reading that will be good in all air density conditions. The correct reading will change, depending on the conditions.
And remember, humidity has very little to do with performance. If it does anything, it will lower the barometric pressure, (just a little) and so the air density gauge will account for it. If it does anything, it will make you feel terrible and that is what makes people think it’s effecting the engine.
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All else being equal; Compression is the Holy Grail.
45 years, in and around karting |
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Daniel McBride
Joined: 30 Jun 2012
Posts: 5
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| Posted: Tue Feb 12, 2013 10:38 am Post subject: |
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Thanks a bunch guys, very helpful. I'll take it to the track and see if I can get a better reading at the recommended settings there.
Cheers,
Daniel |
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John LaBarbera
Joined: 23 Dec 2012
Posts: 14
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| Posted: Wed Feb 20, 2013 4:17 am Post subject: |
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| I was told to set my Hi and Lo at a pop off pressure of 10 psig. I bought a pop off pressure gauge, how do I use it??? I'm a newbie as you can tell... |
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Russell Stevens
Joined: 15 Oct 2012
Posts: 100
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Juan D Gomez
Joined: 28 Apr 2010
Posts: 262
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| Posted: Wed Feb 20, 2013 7:00 am Post subject: |
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| Dan Haynes wrote: | | I think the road racers only rev theirs to about 14,000 but can't say for sure. Maybe they set their carbs differently. Don't know. |
Same carb set up for Road Racing, you also shoot for the same EGT temps. although getting the set up just right is not as critical and you can still be competitive running a little rich. Gearing will determine your RPM but you usually shoot for 13K running by yourself. In the draft it'll go up to 13.5K-14K. 14.5K if pushing. It doesn't matter how many teeth you put on, most usable power is gone after that and the drag is too much at 95mph to get close to 15K. You might see that if you hit a bump.
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JIM SILVERHEELS
Joined: 22 Jul 2006
Posts: 587
Location: United States, Massachusetts, LUDLOW
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| Posted: Fri Feb 22, 2013 1:48 pm Post subject: QUESTION |
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Where is everyone setting their lever height please on the Leopard's Tilly? I just set mine even with the deck. thanks
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