250 EXC 2T Running In !!!
Does anyone know what it says in the book for running in a 2 stroke 250 ? & what are you guys recommendations ??
i was thinking along the lines of; 2 x 15 minute heat cycles & then easy for the remainder first tank of juice ?????
Welcome your sugestions & reasons :-)
Sounds very similar to what I've done in the past with no embarassing side effects What youve said + the usual precautions of not labouring the motor and I reckon you will be fine with this.
Yeah sounds Ok but use cheap 2 stroke oil give the rings chance to bed in properly getting better compression.
Originally Posted by fred
Originally Posted by THE FLUTE
never heard that one before ?????????
Yeah with mordern oils being that good the piston ring dosent cut in to the bore very well and you lose compression. Hawk kawasaki use mineral oil when running in and found over 5 bhp more than when they used fully synthetic to run in
Originally Posted by wardy
Mixture at 50:1 with what ever oil you generaly use. 20-25 mins of half throttle with no labouring then nail it. Must of done this over 50 times and never once had an engine failure.
Whenever I've had a new enduro bike, I've ridden it in to work a couple of times - job done!
I am assuming this is not a new bike or you would have the manual and know what the book says.
Originally Posted by THE FLUTE
If it is just a top end rebuild; then if the bike starts, its run in for me. The idea is a gas tight seal on the rings as soon as possible and the new way of thinking is the quicker and harder the better. The main bearings and big end tollerences on modern bikes are so good as not to worry about.
This is only my opinion I am giving before everyone starts ripping into it. This is an extract from a good link I believe in:
"For those who still think that running the engine hard during break-in falls into the category of cruel and unusual punishment, there is one more argument for using high power loading for short periods (to avoid excessive heat) during the break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls. This is expensive, and it is an expense that can be avoided by proper break in procedures."
Running in an engine is like making love to a beautiful woman - she needs a firm hand, and a variation in the rythm, but not an excessive pounding....
Race it, DON'T HEAT CYCLE.... use it like it you would in a regular practice.... DO not heat cycle....
Let me explain....
Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.
If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.
How Do Rings Seal Against Tremendous Combustion Pressure ??
From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.
The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.
There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!
If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.
Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
which is why more engines don't have this problem !!
An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!
There is no need to "heat cycle" a new engine. The term "heat cycle" comes from the idea that the new engine components are being "heat treated" as the engine is run. Heat treating the metal parts is a very different process, and it's already done at the factory before the engines are assembled. The temperatures required for heat treating are much higher than an engine will ever reach during operation.
The idea of breaking the engine in using "heat cycles" is a myth that came from the misunderstanding of the concept of "heat treating".
Now, imagine if the engine is run in the garage. There is no load on the engine, so the rings are just going up and down "along for the ride". Only a small portion of their surface is actually contacting the cylinder wall. The ring area that does contact the cylinder wears down the roughness of the honing pattern on the cylinder walls. Once the roughness of the cylinder is gone, the rings stop wearing into the cylinder. If this happens before the entire ring has worn into the cylinder and sealed, you will have a slow engine no matter how hard it gets ridden after that point.
The difference between what happens in an engine running in the garage, versus one being ridden is a hard concept to put into written words, so if I may use the sounds that we all can relate to: it's the difference between "zing-zing-zing" and "bwaaaaaaaaaAAAAAA"
During "zing-zing-zing" the rings don't get loaded for more than a split second, whereas during "bwaaaaaAAAAAA", the engine is in 100% ring sealing mode.
I've had 8 two-stroke ktm's in the last five years, and i just pinn it from the first day, never had a piston failiure, never had any problems with my bikes, even after 4 hours of boiling at the erzberg enduro-----