flexpipe length help...

alvin l nunley said:
12,500? A stock KT 100 can easily turn 15,000+ RPM. After you get the correct header length from RLV, work on your tuning. Years ago, with their pipes, we most often ended up setting the carburetor at 1/4 top and 2 1/2 low. One advantage we had was the EGT. Nothing better for tuning in my opinion.
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Al I have read many of your posts and you seem to know your stuff. Can you elaborate on the EGT. What are idea temps for a kt100 with a L2 pipe?
 
mtbikerbob said:
Al I have read many of your posts and you seem to know your stuff. Can you elaborate on the EGT. What are idea temps for a kt100 with a L2 pipe?
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A quick search here on Bob's will answer your question. Use EGT as your search criteria. Or use my name. I've explained the use of the EGT many times.
There is no ideal peak temp for the EGT. On a hot, low air density day, the max might be lower than on a cool high air density day. That's the beauty of it, you tune for the conditions of the day. Your main concern would be, if you've been racing for 4 or 5 laps, with a steady peak EGT, and it starts reading less, simply richen the high-speed. Coming out of a corner, same thing. The EGT registers very swiftly, and coming out of the corners, because the engine is at, hopefully, peak torque, and the pipe is making the pressure in the cylinder higher, the EGT will be reading a lower temp.
This is important; if the EGT temp goes down, the 1st thing you want to do is richen the mixture. If it goes up, you know you were lean, if it goes down further, you were probably rich.
Tuning is tough! (Al Nunley)
 
alvin l nunley said:
A quick search here on Bob's will answer your question. Use EGT as your search criteria. Or use my name. I've explained the use of the EGT many times.
There is no ideal peak temp for the EGT. On a hot, low air density day, the max might be lower than on a cool high air density day. That's the beauty of it, you tune for the conditions of the day. Your main concern would be, if you've been racing for 4 or 5 laps, with a steady peak EGT, and it starts reading less, simply richen the high-speed. Coming out of a corner, same thing. The EGT registers very swiftly, and coming out of the corners, because the engine is at, hopefully, peak torque, and the pipe is making the pressure in the cylinder higher, the EGT will be reading a lower temp.
This is important; if the EGT temp goes down, the 1st thing you want to do is richen the mixture. If it goes up, you know you were lean, if it goes down further, you were probably rich.
Tuning is tough! (Al Nunley)
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Al, can you help me understand why you would use the high speed vs the low speed to richen?
 
Where are your needles typically set?
With the typically accepted tune 2-2-1/4 on the low any more is not going to give much more fuel .
The high being at 1/4 -1/2 there is some room for adjustment .
 
mtbikerbob said:
Al, can you help me understand why you would use the high speed vs the low speed to richen?
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My theory (read my sig) is this. The high-speed discharge nozzle is in a venture. As the air velocity increases through the venture, the pressure drop increases as the RPM increases, allowing more fuel to be pumped into the venture. The low-speed discharge nozzle is not in a venture so the fuel supply tends to be more linear. Just a theory. Add to this the fact that the pipe becomes less and less efficient, as the RPMs increase, thus decreasing the absolute pressure in the cylinder. Detonation is caused, in part, by excessive heat and/or pressure, thus, with less pressure, you can run a leaner, hotter, mixture. Just a theory, yes, but observations tend to validate the theory. At least to me. lol
 
For what it's worth it might not be the pipe 12,500 won't get it done . A decent kt should run 13,800 to 14600 all day long. Sounds to me that you might be gear bound. Shorter flex ,more top end and usually more heat , longer flex better out of the hole and alittle less temp. Be careful experience and experiment should not be in the same sentence. Chuck.
 
When I had my KT setup at Patriot, I was turning it 15,500... It was a stock KT, and I was staying with the Limited UAS field pretty well. It's probably the last time I saw Chuck in person. LOL
 
And that's the beauty of the UAS rules. Grand Nationals aside, week in week out racing punctuated with diverse combinations of kart/motor/driver variations all with abilities to win. We had an accomplished racer in a KT100 powered kart. She was a pixy and I dought if scales touched 300 pounds. She was competitive and she was battling for top place finishes from time to time. One of my favorite UAS karts was a twin limited flathead kart that sounded like top fuel Harley on the grid. When those two motors synced coming out of turn four it was mechanical heaven and defined cool.

A new thread, "My favorite UAS kart" would be interesting.

DK
 
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