I’m asking for a friend. 
Haha. Actually, I’m asking, because I’m doing another engine break-in this weekend, and the thought crossed my mind. What do you think is the best approach to properly do a break in? I know several engine guides have suggestions, but I want to know people’s opinions.
2 cycle or 4 cycle engine?
For Leopards and X30s, we always tape up the radiator, and go out and cycle the engine from 8-12k for a few laps. On throttle to 12k, then coast and repeat. Then start pushing to 13k, then 14k, then 15k, then to the limiter over the course of the next several laps. Keep the high speed needle pretty rich on the carb. Once you get it to the limiter a couple times and coast, then I just start driving at full speed, and maybe choke the airbox a couple times at the end of the long straights to keep it lubed out.
We always aim for a water temp of around 150-160 during break-in. Let everything get nice and hot and settled.
Don’t know if choking it is necessary, but it feels super cool, like you’re a Formula Super A rockstar like @KartingIsLife or @NikG.
Be careful overchoking a reed, cracked reeds bad!
2 laps at 10k
2 laps at 12k
2 laps at 14k
2 laps at 16k
and on if you have a 100c lol.
Drive flat out but choke the engine to maintain the rev. If you lift off you starve the cylinder of oil when it needs the lubrication the most. You need to drive flat out to bed the cylinder in, if you just drive round on part throttle it’ll take 3 times as long.
As a side note, most pistons in TAGs are like throwing a sausage into a wet cave, nice and loose and flap around. Its not like a KZ or an old Formula A that was tighter then a nads nats.
On a side note I once ran a Formula A in during 3 lap warm up
Well, seeing that this was posted in the 2 Cycle forum…
So since I’m running a PRD in this weekend, I’ll post the instructions they give. They’re way more intensive than what people have suggested above. 45 minutes and at least 3 break in sessions.
3.1 Ensure the engine is mounted to the chassis correctly, all mounting bolts and nuts are tight and the
drive chain is correctly aligned with the correct tension. Check all electrical & fuel line
connections are secure.
3.2 Ensure that the accelerator cable is correctly fitted and adjusted and the throttle valve in the
carburetor opens and closes correctly. For starting set the walbro high & low speed needle jets to
turn 1/2 HI & 1-1/4 LO.
3.3 The 45 minutes run-in period should be divided into 15 minutes periods.
3.4 Do not at any time allow the engine to overheat. If the engine shows signs of overheating abort
the session and allow the engine to cool down. Check for any obvious cause of overheating
before continuing. To excess heat may have simply been caused by an overlong on-track session
or incorrect carburetor setting.
3.5 TRACK SESSIONS 1 & 2:
Do not allow full throttle for prolonged periods. Round the engine in short bursts between 1/2 to 3/4
throttle. Do not allow the engine to labor nor remain on a constant throttle opening for any
prolonged period if using a tachometer limit engine RPM to 7500 [1/2] to 9000 [3/4] maximum.
3.6 TRACK SESSION 3:
Gradually increase throttle opening from 3/4 to full for short bursts full throttle can be used for
longer periods in the 4th & 5th sessions if using a tachometer limit engine RPM to 11,000
maximum when using full throttle.
It’s PRD, the clutch is going to fly off and decapitate someone by lap 4 anyway.
Wouldn’t worry about the break-in procedure.
Heh, well that’s encouraging. lol
Based on how work and the weather has been over the past few weeks, I’m not going to get to break in the piston on my KT on track before Sunday’s race. Can I do it on the stand following @NikG’s method?
Another site I visited said, “The engine should be broken in with starting with 1-second bursts of full throttle followed by about 5 seconds of cool down throttle blipping. Gradually increase the length of the full throttle bursts until full throttle is applied for the whole longest straight after about 15 minutes of run time. The 15-minute break-in should be broken into three 5-minute sessions.”
Thanks, I’m running out of time! But then again, who isn’t with karting?
Typically you get a 10 minute warm up in the morning. I would think you could do my method in that session.
I don’t particularly know the KT100 very well but my understanding is its not an engine that’s run to edge of its capabilities so the chance of seizing it because its run in to fast is surely slim? Maybe someone else could jump in on that one.
Our race day schedule generally is a 5 minute practice in the morning, which if you’re on it hard, you can get maybe 8 laps, before a 3 lap qualifying. If possible, I’d like to do it on the stand. I’m going to be out of town on Saturday so basically I need to be able to show up on Sunday ready to go.
This is pretty much what my Kart Store suggested for me