I usually run a 99 Honda CR125 in my shifter chassis. It’s mostly stock, running the Keihin PWM 38 pump around system. I notice when everyone is firing the engines for the first time of the day, they get a considerable about of smoke, and it continues to smoke some until they get going on the track. Mine never smokes. I’ll get a small puff or 2 when it first fires, then nothing. It seems to run fine, and doesn’t get hot, makes seemingly decent power so I’m not too worried, but I do wonder why mine doesn’t put out near the smoke everyone else’s does. It’s also a bear to start when cold. If it didn’t have a choke I’d spend a long time trying to get it to fire.
I don’t have my notes in front of me so I can’t share current jetting, needle, or position settings. Could my pilot jet be too lean? What jets/needles/needle position do you guys usually start with? Once I get my notes around I can update what I’m currently running.
I’m not too worried about breaking, because like I said it seems to run fine on the track. But I would like to make sure it’s ok at low RPM/cold running, and make sure I’m not missing out on any potential power. I have been running Klotz Super Techniplate at 18:1. I heard synthetics do smoke less, but it seems like I should still be getting more than I do.
Seems like you’re running a lot of oil. I have always run 32:1 with Motul 2T. Jetting will definitely vary depending upon elevation and temperature, but below is what I have run on my Stock Moto Honda at sea level and 60-70 degrees F.
One of the guys I run with recommended that mixture. He’s been racing for a long time, and really fast on the track. Usually either first or second in his class. I tend to listen to what he says. I always forget to ask him about the no smoke issue I have, and when I see him next I’ll be sure to bring it up.
But with the heavier oil mix, it seems like I should be seeing more smoke than I do. I’ll get access to my notes and carb tomorrow and report back what I find out.
Maybe they oil down their engines when they’re done racing.
Maybe it’s the way they shut down. If you rev it then cut it quick it will not load up with oil, if you let it wind down slow and die it will have a bunch of oil in it on start up.
Can you keep pace with them? Maybe they have to be richer because they’re pushing hard.
BTW, Klotz Super Techniplate is 20% castor.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience