Engine Break In


Berkeley, CA
What is the proper brake in process for a 2 stroke gas engine? I never really thought much about breaking these things in, always thought that was something only for nitro since they don't have the same compression methods and have pinch.

Anyway, enlighten me, what should I be doing to new gas engines before running them hard?


Active Member
Fredericksburg Va
Run it hard from the start. seats the ring as fast as you can to prevent blow by. did this with my cy29 head kit and it just got faster and faster. You'll see a big difference in rpms going through your 3rd tank. don't be afraid to open her up


Bajastafarian Madnes
PLUS member
yup. start it up, run it for about 10 minutes to wamr the motor up well.

then start doing tuning runs.. Run at any given rpm for 10 to 15 seconds straight. immediatly shut off the motor, pull the spark plug out and look at the ceramic piece under the electrode. you want that to have a Medium Brown color to it. as long as your plug is a medium brown color thru varied rpm runs. ie. idle. low rpm, low/mid rpm, mid rpm, high high rpm, and finally WOT runs, you. ll be good. each time after a 10 second run, stopping the motor as fast as you can, pull the plug and check the color.

you L needle will handle fuel flow from idle to about 1/3rd throatle. the H needle will then ADD fuel to the Low needle for 1/3rd throatle to the top rpms.

clockwise Leans the needle. counter-clockwise Richens the needle.

color of plug should be medium brown, safe bashers tuning, to a medium dark tan (performance tuned- this is where most your track racers will tune.

performance tuning is on the edge of being too lean. you really want to know the motor, how it run, and how it tunes b4 you try to performance tune it.

its only a stumble from performance tuned motors to a squeeked top end and a repair bill.

so i suggest tune for basher tuning. medium brown color to the plug.

if its dark brown, black in color is proly rich, and needs to be leaned up a tad, if its light tan or lighter in color its TOO LEAN, richen the appropriate needle.

also know you can not tune a gasser like you would a nitro, they will not take a lean run like a nitro will
use 1/18th to 1/12th turn on the needles. once the needles are close to right, you ll notice a differance in the power and top rpm.

just use small needle adjustments, and keep an eye on the plug color. keep it medium brown and your motor and your wallet will be happier.


Mpls/St. Paul
I broke mine in the first race of last year. Never started it before that. All I did was keep an eye on the mixture. It still screams and I've been running weekly club races as well as a couple of big events (week long running all day).
My .02
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