egt on kt100

spincycle

Member
wondering what temp range is desired on a mychron egt lead on a superstock kt100 with RLV L4 pipe, walbro wb3a carb on gas and on alcohol...Thx!
 

Ted Hamilton

helmet painter and racer
As high as you can get it without crossing the peak and falling....ie. it doesn't matter if it's 1100 or 1400, so long as it doesn't rise, then dip back down due to detonation....you want it to keep climbing until the end of the straight, then cool off-throttle for the corner, then repeat... See Al Nunley's posts on the matter from some time ago...
 

Phiddy

Member
Really depends on how tight the motor is setup. After break in is done I would say if you ran 1250* on gas it would be close, and safe. Once you are familiar with it, tune it closer to that line. Not sure on alky KT's? I would guess 1000* on alky would be also safe. I would also recommend a consistant fuel/oil mix. Never know whats coming out of the local station pump? Buy a top rated race fuel for it, it will maybe save you someday? Oh, and I mount my probes as close to the flange as possible.
 

spincycle

Member
Im on gas, mixing VP C12 with Burris hi-rev 8oz/gal....there is a fitting on the exhaust manifold for the egt probe....motor was purchased used, really no idea on how tight it was built....thx!
 

AudiOn19s

Member
does can / pipe / expansion chamber have an effect on EGT?

With 75-80 degree air temps and Spec WKA pipe (SR-Y) we only see low 1100's. I'm afraid to go any leaner because I'm already at the lean end of where the builder told me to be on the carb and I'm afraid to stick a piston looking for every last little bit.
 

Chris Cooper

Premium User
1250 would be an upper limit - check your plug and header for color. If it's a nice brown color, you're in good shape and you may be able to go higher; just watch the plug and header.

Also, the big advantage of EGT is that you can check to see if you're too lean near clutch engagement. Watch the EX temps - if they drop at clutch engagement, open up the low speed a little.
 

Phiddy

Member
The real advantage of EGT, it is "real time". Its whats going on now, not 30-45 seconds ago like head temp. Also ambient air temp doesn't affect the reading. The ambient air does affect the mixture or tune though. The Mychron numbers are so small they are hard for me to read underway. When I used a Digatron I could tune the needle and watch the temp change as I turned it. In the photo tuning and watching the gauge.
 

Attachments

AudiOn19s

Member
One last thought here. When I originally inquired to my builder about EGT's and was only getting a little over 1000 degrees he immediately asked "Are you using the jam nut on the sensor?". The answer to his question was yes.

I didn't want to cause too much of an exhaust restriction by having the sensor all the way in the exhaust flow but apparently it makes a difference in the reading. Sure enough I pulled the jam nut off of the thing and installed it all the way in and my EGT readings immediately went up 100 degrees the next session.
 

nobozos

Member
This past weekend we ran 1200-1250 all day long at Charlotte with the enduro on gas. Air temp was 85-95 tsow pipe for what it's worth. Info ^^^^ above is spot on. On alki short oval 850-1000 about topps . Chuck
 
The real advantage of EGT, it is "real time". Its whats going on now, not 30-45 seconds ago like head temp. Also ambient air temp doesn't affect the reading. The ambient air does affect the mixture or tune though. The Mychron numbers are so small they are hard for me to read underway. When I used a Digatron I could tune the needle and watch the temp change as I turned it. In the photo tuning and watching the gauge.
Nice Pic! Old skool NCK at Sears Point. Love it!
 
IMHO etg is just a "reference tool" just as cross weight is to scaling a kart..... it will vary with the way the motor is built, the probe you are using, how it is mounted, where the prob is mounted, the fuel you are running, how you drive etc etc etc..... One needs to learn to read a plug and find the optimum EGT for their setup. But to address your original question....not sure what you are referring to by a "super stock" KT?..... the old IKF superstock rules were reed/rotary only.... in general, the safe egt range for an IKF/WKA legal KT on non-oxygenated race gas would be 1000 - 1200. I've never run one on alky. Wouldn't waste my $....would build a sudam or reedjet on gas before I'd go kt on alky route. but that's just me.
 

Don K

Member
Our dyno proved the worth of egt. Tuning to the top and not past is the fastest the motor can be. Egt is an excellent tool for tuning to the front of the pack. It doesn't matter if the probe is in the exact location, doesn't matter if it is in to far or out to far. It is the number that says you are at the best you can be. You can guess by seat of pants or trust your tool. Tools rule.

Additionally, if your not looking at the wet line your not in the game. One to one and a half inch.

Works for two-strokes and four-strokes as well.

DK
 

Don K

Member
2 stroke wet line tuning sets the correct flex length from the face of the piston to the junction of the first cone. Expansion chambers work on the principle reflective pulses first drawing the fuel charge through the cylinder out the exhaust and then rams it back into the cylinder to pack the cylinder for the most fuel charge. The flex length determins if just enough fuel is left outside of the cylinder to prevent over heating or worse. To short flex and the wet line is to close and hot to the piston, to long and the wet line is to far from the piston face and the fuel doesn't get rammed back into the cylinder efficiently. With the KT or other kart engines we are only concerned with tuning for wide open throttle. About an inch to inch and a half from the beginning of the manifold cylinder juncture. It is where we settled for safety and performance.

This same principle works for dirt bikes too. Difference is the dirt bike needs the carb tuned for the three stages of carburation because the flex is not adjustable.

DK
 

spincycle

Member
2 stroke wet line tuning sets the correct flex length from the face of the piston to the junction of the first cone. Expansion chambers work on the principle reflective pulses first drawing the fuel charge through the cylinder out the exhaust and then rams it back into the cylinder to pack the cylinder for the most fuel charge. The flex length determins if just enough fuel is left outside of the cylinder to prevent over heating or worse. To short flex and the wet line is to close and hot to the piston, to long and the wet line is to far from the piston face and the fuel doesn't get rammed back into the cylinder efficiently. With the KT or other kart engines we are only concerned with tuning for wide open throttle. About an inch to inch and a half from the beginning of the manifold cylinder juncture. It is where we settled for safety and performance.

This same principle works for dirt bikes too. Difference is the dirt bike needs the carb tuned for the three stages of carburation because the flex is not adjustable.

DK
Thanks for the info :)
 

spincycle

Member
raced the other night, finally have time to look at this closer on my own kart today, would you define "wet line" as the point inside the flex where there is an obvious difference in color from end to the other from where there is dark to light, or should there maybe be some unburned excess fuel sitting in there? BTW, ran it on a mixture of 8oz burris hi-rev to1 gallon of VP C12, max rpm was right at 13,000 and EGT max temp was 1120...Thx!
 

spincycle

Member
"wetline" appears to be at about 1 1/2", spark plug looks a little black with some wetness on it, may have been running it a little on the rich side, but was trying to avoid leaning it out too much...still trying to get the hang of driving with one hand....:)
 
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