Running in time and method

[tonyc]

I have just fitted a new piston, cylinder, gudgeon pin, rings and bearing to an ETZ 251. How long does it take to run it in and how should I do it?

[manumensa]

Hello tonic.

An old DDR book. Text from the web of Pedro.
Thank you Pedro!

Google traslator :


"Do not do anything wrong," does he think he will first use a new motorcycle, or even a new engine fitted.
A fearful and hesitant attitude has no place because it is not going to lose value when it comes to awaken the temperament of an engine, and bring slowly to give the best of himself.

We have done many filming MZ motorcycles, all following the same recipe, you no longer feel bad our method of performing the shooting, or showed signs of weakness to yield insufuciente. On the contrary!

The same principle as new shoes fit is valid when making the engine running, where the sliding surfaces must comply with and support each other. Today, machining surfaces estánderes has reached a quality such that the completion of filming involves no science. During the first hours of operation really is completing only mutual adjustment between the moving parts, including piston and cylinder liner segments. The best preconditions for this purpose and provides manufacturing and installation of the engine (only the materials used in their manufacture).

MZ is an engine with a propeller that can go without more of a long journey. This is even advisable necessarily prevent the use on short trips during the filming.
However, on a trip of this magnitude should one take the time to do the shoot: you should not play any role the time taken to reach the destination. Any brutality makes you ask the engine more than it can supply. Therefore, it is best from the weekend raised the motorcycle without a goal. We should only have in mind the goal of achieving good shooting, then neither will anything wrong.

How do I start?

The shooting is not an automatic to go a certain amount of miles or meet a certain hours of operation. It is "as" what has the greatest significance. Investigate this more closely.

One circulates in the 2nd gear and wonder: when I change to 3rd or 4th? What are harmful rotational speed, or do what we are in an rpm ETZ 250/251, when it reached a speed of 50 km / h in 3rd speed?

cuentarrevoluciones.gif (14.1 KiB) Viewed 1961 times

Fig.1a. Graph relating km / h with rpm depending on which gear you are cruising.

Anyone who owns a machine with counter, one must read on the clock the number of rpm. Otherwise we will be guided, especially during filming, with the MZ velocity diagram (Fig. 1), to find out what speeds are reached at different speeds to approx. 4000 rpm. Not much more than the scheme of 4000 rpm is circulated during filming.

But back again to the speed chart for the ETZ 250/251 of Figure 1. 50 km / h in 3rd speed according to this assume 3500 rpm! A similar scheme is not a new engine destroys nowhere near!

Only in the interval from 5200 to 5400 rpm the maximum torque is reached (which is the more "pulling" the propeller) of this engine. The velocities corresponding to these regimes should be remembered, as we know, during the shooting and additional adverse conditions, which speed up our engine since it is easier.

In the case of the ETZ 250/251, this happens in 1st gear from the 32 km / h in the 2nd from the 53 km / h in the 3rd speed from 75 km / h in aa 4th from 95 km / h.
If the speed drops below these limits at different speeds to tackle a steep slope, or by a strong headwind, the engine starts to "pant" is "torture" itself. Under these conditions, even to the throttle and the speed increases under such conditions.
The engine can not transform the excessive air-fuel mixture that is offered, because the transmission ratio change is not adjusted to the resistance it finds. The engine can only develop its full strength when it is held between the rpm values for the maximum torque and maximum power. So down at the right speed!

Three rules for filming

Knowledge derived from these three principles for the shoot:

Rule 1: do not ever drive the engine at too low rpm! This means that regimes below the maximum torque is not seized with a steep slope or overtaking.

Rule 2: avoid constant speeds! Whoever engages in the shooting on a highway, does not provide the best conditions for it. The variation between high and low regimes, such as in driving on the road, and which requires a frequent gear changes and speed (curves, hills, valleys, towns) will feel the engine much better.

Rule 3: the number of revolutions increase gradually with increasing intermediate cruising speeds longer! This translates in practice to the following: for example, has already circulated in an ETZ 150 new, for 100 km between 40 km / h 70 km / h, and has frequently changed from the 4th to the 5th speed and vice versa. Also the 3 speed is inserted occasionally. However, the 4500 rpm were not exceeded at any time.
Well, it's time to get used carefully turn the engine to higher speeds (the end of the day, later the motorcycle will achieve eg 90 km / h in 4th speed).
It try to open the throttle a little more than until now, before switching to the following March. Also in 5th, to spend a short time of 70 Km / 80 km / h. At first, this one will take place during a space of 100 to 200 m, and then for ever more space. In doing so, you will notice the change between cruise speed and breaks in middle that slows down at low rpm, the engine makes considerably more cheerful in his reply.

If at first you had the feeling that the engine did not allow the gas "more" that was offered, and set aside 60, 80 km of running is more sensitive to the twists of throttle. This is the indication that the friction losses between the various moving parts have been reduced.

The seizure of the piston (seizing)

Now comes the point in our opinion, is the risk of shooting itself motorcycles: the temptation to give the engine full throttle and prepared ... Is great!
"How much pull?" Is what one wonders, and is already leaving "climb" to the tachometer needle. Who, at this point, no special attention, not only can cause damage to the engine, if not even himself.
Attention should be paid to the sound of the engine, trying to find out if the engine speed rises to its joy or, conversely, just sounds more serious, or even begins to creak (sonar). If the latter happens, the test should cesarse full throttle, and after several miles of walking, try again.
If in this situation, it still leaves the full gas, piston seizes up within seconds in the cylinder with a shrill and grating. A seizure of this type occurs very rapidly as the piston expands by strong heating and no longer has enough freedom of movement in the cylinder. Stiffness is favored if the gas is cut off suddenly after having forced the engine immediately before.
The abrupt withdrawal of the gas at high speeds results in both the cooling (due to the almost total absence of fuel-air mixture) and lubrication (no oil mix = no) are not sufficient. Then the piston is seized, and who does not pull at the time (better yet a little before) the clutch, he will fall hopelessly. With the rear wheel locked at high speeds, few are mounted on the motorcycle!

The index and middle finger should be positioned on the clutch lever, ready to operate it if necessary. Suspecting a jamming (seizing) is driven clutch lever quickly.
Even if the clutch the engine, it turns off, which means that the piston has been stiff in varying degrees, with the rapid clutch has avoided direct harm.
In these cases must be left by the motorcycle roll inertia (momentum). The cooling of the cylinder during this short interval is, in most cases sufficient to relieve mild stiffness, and by a cautious disconnected, put the engine moving again. After first trials to be forgotten "butt". Only gradually more could you ask cylinder "scratched" because of the pressure areas should be smoothed stiffness by a relatively cautious driving. The film was stretched by a jamming of this type.
When fever affect us "give cane" should think about them. A certain restraint in this respect is rewarded.

A question arises with some frequency the motorcyclist: can ruin a MZ engine for driving with few gear changes and lower speed? Or put another way "if there has been a very content running the engine when full power will not yield?

In practice: what was not done during the shooting can not be retrieved later!

The most important process that takes place during the shooting is the smoothing of the sliding surface for the piston in the cylinder. The real journey of the piston, limited by the upper and lower dead point, is not constant along the whole range of revolutions per minute. Conditioned by the inertial forces, the deadlock is highest at high speeds, some fraction of mm higher than at low revs.
As in the point of the motion (TDC) is produced by one notch wear clearly visible, and during filming try to locate the step so as to allow sufficient freedom of movement to the upper edge of the piston, and we encounter after it collides with a recess or step too low, caused by an operation at medium or low speed (careful filming).

Saludos/Regards.

[DAVID THOMPSON]

what i do on new or rebuilt motor
1 do not run at low rpm common term in English is LUG
2 do not over rev it
3 do not run at a steady speed for very long
4 this applies to both 2 and 4 cycle motors
5 on a very hot day pass on riding it unless you need to go
6 on a 2 cycle i use the oil sold in my area for STIHL 2-Cycle chain saw Engines
but use 9/10 gal of fuel for the bottle that says for one gallon
on a bike with auto lube pump i use the oil the bike manual calls for
and do make sure the pump is working ok
and on some bikes the auto lube pump does not run if the clutch lever is pulled in
so remember to not set in gear at a long stop light or in stop and go traffic
get it in neutral as much as you can
dave
i am not too green with my two smokers i think they need to smoke a bit
my 20 year old STIHL fs80av weed eater still screams and runs good and has mowed a bunch of weeds

[tonyc]

All was going well, but today I went out and went up to 60mph and the engine now knocks when I am slowing down. It's done this before, but not since I put the new cylinder and piston on. The idle has also been a bit eratic of late. Help...