Originally Posted by
Do-Over
Thanks buddy,
I hate it that you had to right all that out on my behalf but I appreciate it all the same. I understand the tolerances and why they have to be so perfect. I used to race 2 strokes and have done my share of rings and/or complete rebuilds in the garage, usually twice a season. I can usually get what I think is a good tune on 1 needle or the other but believe I may run a lean top that disguises a rich bottom or vice versa. It's that balance for the sweet spot that evades me. I think I just need more time to develop a better "ear" for this. I can get decent run times and steady temps also but my engines still don't sound like the pro's at the tracks I go to but I can be patient and work up to that. Thanks again for your time and I apologize for the lengthy nonsense, I'm just a talker I guess...
No problem!! In a nutshell, ALways verify you idle gap is correct first before you try and tune, it should be approx .5 to .8mm, then just always tune the top needle first, and dont even start tuning until the engine and chassis are heat saturated, Run the engine for at least 5 minutes before you start tuning. Start with the top, Richen the needle to where it will not open up and clean out, the just keeep leaning it an hour at a time until it screams, Now you know you are at the richest part of the top needle, if you back it out an hour or 2 and it goes fat nad will not "scream" then you know you are at a rich but good running needle setting for the top. You can go in "leaner" later, but this is a starting point. then after tuning the top with those high speed runs, then bring it in and see how it idles. if it idles high then richen the low speed needle until it idles low and smooth, if it want to die and stall, lean the low end needle until it idles steady. You should not have to adjust the actual throttle idle screw at all, excpet for maybe an hour once the idle gap is initially set, so the low needle screw is what you will be tweaking to in a sense , set your idle at this point.
Then just throw it on the track, and check temps you can then lean the top out more if your temps are on the cool side, and once you feel you have the top leaned out to where it screams but the temps are good and there is still good smoke coming from the exhaust, then go back to the low speed nedle and re-adjust it. how it idles will tell you if you need to lean or richen it after you do more adjusting on hte top. Then tune the bottom for steady idle and strong accelration, just be careful not to go to lean on the bottom. I see it all the time, guys tune the bottom to where it runs good,then in the midddle of a race 5 minutes into it the bottom loses punch because it got up to temp and was to lean on the bottom and they had no bottom end power. Thats why it good to tune when the engine ii is up to race temps.
A lot of guys try to tune in the first minute or two and have problems later after it warms up. Anyway Practice makes perfect.... Hope this helps!
Take care,
Lance
Rcrenew.com