Why do people want to use a different oil for the first minuets of a motors life?

I have been racing using two stroke motors for many years, from club level up to Works team level, and we never used any different oil for the first few minutes of an engines life. In fact if we changed oil at any time, we would totally strip the fuel system and carbs to flush out the old oil before ever adding a new one, especially going from a natural to a sythetic based oil.

I have heard that its to allow the rings and bearings to "bed in", but in reality the revs we run these motors at ring fit is far more important than bedding in.

The wear on the piston in the first few seconds of an engines life is greater than it will for most the remainder. So why is it recomended we sarifice wear on the piston, to get the rings to bed in that bit faster.

Is it to get the bedding in process over with that bit faster, or is there a real reason?

Peter

Your carb is another 13.5mm venturi like the others. It's a number I haven't seen before. My vender says DL uses different carbs probably depending on supply. They are all 13.5 mm carbs and look the same. What the differences are in the models I have no idea.

As for the ignition all of mine have a small green sticker that has a date on them and say version 2.

First hours.
A mineral oil has a very low film strength which allows all moving parts to wear out faster for a better fit. Imagine the cylinder of a new engine to be nicely round and the piston ring a bit oval. The idea behind breaking the engine in is to have the piston ring take the shape of the cylinder which results in less friction. Less friction = less heat = higher performance. Because most synthetic oils are actually much better lubricants than mineral oils, this process will take much longer and therefore the chance of damaging the engine during the first runs is higher.

OK so you are saying people use mineral oils because they are not as good, and the want the ring/piston to wear faster to speed up the running/bedding in process. Isnt that a risky option as you have no idea when to change, it could take 10 minutes or it could take 75 minutes. If it finishes in 10 minutes then the rest of the time is just wearing out a good motor.

How can a better oil damage an engine? Some mineral oils will damage the seals in an engine, as will some strange synthetics, but that will happen at any time you use the oil not just the first few minutes. The better lubrication qualities of synthetic oils will keep the motor cooler, and more importantly when the mixture is a bit too week, the oil is also reduced, synthetic oil will still keep working, as you dont nee anywhere near as much oil compared to Mineral oils.

Surly the best option with a new engine is to use the best posible oil, and use a higher ratio of oil to fuel rather than mess arround changing oils.

OK I can posibly go with that argument on an old motor where the cylinder has worn, or has been distorted due to overheating, and you want to fit a new ring/piston. But on a brand new motor, are you telling me the manufacturers do not make the cylinders round?

On plain bearing motors, like your average car engine, or the majority of Glow motors, I can take your point about the film strength as caster is just about the best oil for fourstroke motors. (not YS) All of the current petrol motors have roller bearing big and little ends, so there is no need to use mineral oils.

Changing oils can be quite risky as one or two synthetic oils do react with mineral oil and turn to glue. Unless you are sure the best thing on a new motor is to stay on the oil you plan to use.

Peter

Ideally the cylinder and ring of a new engine fit perfectly and are perfectly smoothed out but this is never the case, especially with cheaper engines like DL.

I agree, no bore is perfect, even the best racing engine needs a short time to allow the rings to bed in, and the less care that is taken on the honing of the cylinder the longer the running in process.

These motors are very well made, they may be cheaper than the DA's of this world, but the DL, Area 51 etc are all well made. How many posts are there on here that says the motor is turning a 23a prop at 7300 rpm after just 15 mins running, the answer is most of them!

It really bothers me that so called experts tell people new to this wonderfull hobby what is basicaly the best way to reduce the life of their new motor. If you are going to use the motor in competition a week after you buy it, and you need every last 100 RPM, then it may be worth it. But most of us have far more power than we actually need, so waiting a few weeks for the motor to reach its best is no big deal.

Far better to use the best oil you can get, add a little more at the start, then as the motor settles in reduce the oil to the optimum level. This will give you a motor that will last for years giving great performance, flight after flight.

Peter

Everyone has his/her own methods and most will work out fine. But if you want to squeeze each and every ounce out of your engine, a break-in period on mineral oil is the best way in my opinion. My DL does 7900rpm on a Vess 22A. I have 3/4 gallons Lawnboy Ashless 32:1 mix left, think I'm gonna feed that to my Volvo and bolt the Vess 23B on tomorrow I have 2 gallons Amsoil Saber 80:1 ready. Will post some results.

And if you're concerned about any chemical reactions between the mineral and your preferred synthetic oil, simply mix a drop of each and let it sit overnight.

I just finished doing my second attempt at rebuilding my first DL50 after the bearings spun. The first time I rebuilt last week the bearings jammed tight and were binding. After disassembly I found that the new crankcase I bought had a small ridge in the rear bearing cavity causing the bearing not to seat all the way. So when I tightened down the propshaft it pulled the rear bearings inner race forward causing the binding. I had used Loctite 620 so it took alot of heat to get it apart again. I played it safe and ordered new bearings again and this time it all went together correctly after cutting out the ridge that was left over from when DL machined the crankcase. I had a spare DL50 on hand so it replaced this one in my Wagstaff 300. This one will be destined for a 33% Spacewalker now that it is rebuilt.

Hi, i posted earlyier this week to say my dl50 was not runing well. It was mis firing or that how it sounds. Well i have tried again tonight to fix it. I set the mixture, but the motor is still what i would call missing. I move, rerouted the ht lead a little and that helped a little the motor ran better, but still not perfect. I changed the plug, but this made no diffrence. I then noticed that the rudder was moving and the throttle arm moved to through inerferance. I have never seen this before. The model is on 2.4. I was touching the throttle servo linkage when i turned the ingnition switch of, and got a shock. Any ideas whats going on?

Check the cap, be sure it is fully pressed onto the plug....start the engine in the garage, or back yard at night, and kill the lights...look for sparks If you power on the ignition and get hit, it isn't grounded properly.

Hi Gents In need of some advice DL50 as now run for 1hr50min but it just wont start, it fires, it flood, when i start it with the electric start it runs fine but hand start never any ideas what to try next.
PLUG is NGK CM6 20th gap
fuel 30% oil
I have changed the reed valve (not sure why but had to try something)

any help please

Hi, i have tried that and no cannot see a spark, but i think that it is the probblem. I just dont want to buy a new ignition just to test it, but i cannot think of another way.

30% oil? 1/30 I hope. In case of the latter, your engine is most likely running soaking rich.

...even without seeing a spark, if you are getting zapped, the ignition isn't grounded.

Does that mean it is broken? Can i do anything, or is it a new ignition?

Sounds like you're using metal linkages and clevises. Never use metal on metal for moving parts.

....could just be a bad cap, and/or grounding spring inside. As for your pushrods, that's a good point made above....go ahead and use the metal pushrods, but use nylon ball links or clevis' to prevent any metal to metal contact.

Hi, yes metal linkages, but with plastic ends on both sides, on choke and one end on the throttle. The other end is metal onto the cardon bit on the carb. When i got the shock the choke and throttle where off the servo anyway as i was checking if it was getting back to the rx that way, even though i could not see how. Is there a replacement after market cap i can buy?

www.ch-ignitions.com or PM user TKG on here. Do you still have the little grounding spring inside your cap?

Hi, ni thats a thought!!!!! No not seen a spring. Could that be it???

Did you get a spare spring along with your ignition in the new DL-50 box? Or did you get this one used? In any case, you can get an extra spring. Bob at DL-USA.com, TKG on here, or call ch-ignitions and you can get one. You'll have to disassemble the cap to put the new contact spring in place.

Yes got it new, but dont remember a spare spring. Will look in the morning. Thank you for the help. I would never of worked it out. Do you think this will cure it?

The RC EXL ignitions appear to be pretty robust, I doubt there's been any harm to it otherwise. Fitting the contact spring should cure the grounding problem, RF interference...etc. So its a great place to start.

Many thanks

Howdy All.
I have read through most of this thread and have found little to no reference to "Timing" on the DL50. Most other engines can be advanced and retarded to gain optimum hp yet carburetor settings are all that's referred to for optimizing the DL50. Is the timing fixed so it can not be changed? or is the factory setting always perfect?