Originally Posted by pro4_racer
ok, so does this sound right for heat cycling break in?
MM, do you agree with this?
here is what i plan to do:
slightly richen mixture
run engine for 3min at slow speed and let fully cool down with piston on bottom of case. repeat this until 15min of run time has passed.
run engine for 4min at slow to medium speed and let fully cool down with piston on bottom of case. repeat this until 25min of run time has passed.
then onto track tuning and just leaning it out slowly bit by bit and if the engine hesitates turn back needle 1/4 and continue leaning until it runs good.
In Response to Pro Racer
Hey guys i havent had time to read all the posts including Ron's break in which im sure is great god bless him !
So ill just answer with the way i recommend , if ive repeated info already said i apologise
Ok
Clean flush the motor
Fuel up with same fuel you intend to run on
Pre heat engine with hair dryer to loosten up ( tight motors need this)
Start and very quickly tune HSN to clean 2 stroke , not rich not lean just nice
Put it on the ground on hi traction surface and run the thing around up to half throttle, Cool BDC and repeat for say 4 to 5 tanks depending on the situation
By the 5th tank it will have done some 750,000 revolutions , its ready to to go hard .
Ok reason it has to be hot ? So the sleeve expands to operating temp, this relieves the piston of smashing into an un expanded sleeve and linishing its self. Its not heat cycling like in lapped iron engines that need to be conditioned, it does help settle the motor but with the materials used one hot run will do this, the repeated heat cycling is purely to condition the motor to its desired operating temps. Running in an engine cool will create a certain tolerance fit between the piston and sleeve, the problem is when you go to lean on it and it gets hot the sleeve now expands further and can create loss of power and blow by.. Not to mention TDC notch.
Second thing , take your temp gun , remove the battery and throw the little F$#KKER in the ocean . Learn to use your ears , they will tell you much more of whats going on with your donk ( engine)
Now whatever the engine likes to run at thats the temp its happy with.. There are too many variables from situation to situation to recommend a temp or a needle setting. Things that will change this are fuel type, pipe, tank, pressure line, tyres, body etc etc
So i hope this helps guys
Cheers MM
PS one thing i forgot to mention, depending on how tight the motor is new the engine might take a few litres to come into its own. anywhere from 2 to 5 litres , you will know because it will start to pick up in performance and acceleration. Temps during run in will go all over the shop, thats why you dont need to use a temp gun, it will confuse you .