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4 cycle lubrication

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Old 07-18-2010, 07:24 PM
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a.bailey
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Default 4 cycle lubrication

Hey everyone.

I have an ASP .61 4 cycle engine and I'm wondering how the fuel gets to the crankcase. I have a machining background and from my inspection of the head I see no way for the fuel to get to the crankcase. I'm just curious about it and I'm wondering if there's a way to improve lubrication.
It seems to sound pretty rough from the back while running it on my break-in stand.

Thanks.
Adam
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Old 07-18-2010, 08:52 PM
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Default RE: 4 cycle lubrication

My understanding is that oil makes its way into the crankcase via ring blow-by. I know that's the way my Saito .80 works and I've never had a bit of trouble out of it. Before running your ASP again remove the back cover and make absolutely certain there are no metal particles left over from the machining process. I've heard of those engines (and the Magnum brand from the same manufacturer, Sanye) sometimes having some machining debris still present. Also turn the engine through and see if you feel any roughness from the bearings. One thing is to make absolutely certain that your fuel has enough lubricant. Magnum (same as ASP) recommends 20% castor oil and no more than 10% nitro. Make sure the glow plug is one designed for a 4-stroke as well.

The roughness could be something as simple as an engine that still needs breaking in, but giving it a good going over never hurts.
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Old 07-18-2010, 08:53 PM
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Default RE: 4 cycle lubrication

Most 4-stroke glow engines rely on some oil leaking past the rings to lubricate below the piston (crank/connecting rod/wrist pin). Seems to work OK.
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Old 07-18-2010, 08:55 PM
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Default RE: 4 cycle lubrication

Fuel doesn't get to the crankcase. It goes directly from the carb into the combustion chamber. The lower end of 4-strokes get their lubrication from blow-by gasses and oil that goes past the piston and ring into the crankcase. That's why they have a vent, to provide an exit for the excess oil. It sounds like a hit or miss method, but it works.
Paul
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Old 07-18-2010, 10:57 PM
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a.bailey
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Default RE: 4 cycle lubrication

Another question....
Is it normal for the exhaust valve to leak before the engine is fully broken in? The intake valve seals good but the exhaust valve leaks. I notice it a lot when I crank it over by hand. Does it get better the longer the engine is run?
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Old 07-19-2010, 05:56 AM
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Default RE: 4 cycle lubrication

Hi
valves should not leak, they should seat properly. I would check the valve lash to ensure you have the correct gap! It could be that too little gap is keeping the valve from seating properly.
This could also be the reason the engine is running roughly for you as you will also be losing compression. Set them up correctly now and then recheck after run-in.
As far as lubrication goes, some oil gets to the crankcase via piston ring blowby and lubricates the bottom end/cam gear /valve gear. Its a good idea to prelube these areas prior to breakin as it will probably not have any lube there from new. Most manuals tell you to do this prelube as a lot of wear will take place till oil finds its waycompletely through the engine.

Let us know how it runs after adjustment.

Regards
Steve
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Old 07-19-2010, 09:34 AM
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Rodney
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Default RE: 4 cycle lubrication

I have found that it is wise to always check the valve settings, even "new out of box" as I have found some not properly set. Again, after the first hour of running, it is wise to check again as initial wear can cause some change. After that, I only check if engine performance is changing for the worst.
Another thing to watch for on 4 strokes, if you use after run oil, it needs to be injected into the crankcase in order to do any good. The bearings that need the protection are located there and putting after run oil into the carb or glow plug hole does little if any good.
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Old 07-19-2010, 12:20 PM
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Default RE: 4 cycle lubrication

The valve lash is properly adjusted. I even took the rocker arms off and cranked it over several times. I could hear the air leaking through the muffler.
I plugged the exhaust and the compression was much better. I heard no leakage through the intake so I know the problem is limited to the exhaust valve.
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Old 08-19-2010, 07:01 PM
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Default RE: 4 cycle lubrication

Still having the valve leak issue. Anyone have any suggestions on how to fix it by any means less than a new valve and possibly a new head? I took the valve out and there's a small groove where it contacts the valve seat. I'm thinking about regrinding the valve. If that doesn't help I'll order a new Magnum head and valves.

I love 4 bangers! (someone would have to force me to go back to 2 stroke)
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Old 08-20-2010, 09:47 AM
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Default RE: 4 cycle lubrication

I had two of these 61's, an ASP and a Magnum. They were the same except for the name.

The Magnum had a leaky exhaust valve. I tried all sorts of lapping things to get it to seat completely but was never successful.

However, in running the engines, the Magnum ran just as good as the ASP.

I traded the engines to a friend. He uses the Magnum more than the ASP. He's had them for 5 years and never done anything to the Magnum except use it.

I suppose it still leaks?
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Old 08-20-2010, 12:18 PM
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Default RE: 4 cycle lubrication

Just an FYI. I fly with a fellow that is running an ASP and he was having no end of trouble trying to get it into tune and run right. Someone mentioned he should try to run it without the pressure line to the tank. It cured all his problems and the engine is running fine now??
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Old 08-20-2010, 12:44 PM
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Default RE: 4 cycle lubrication

The problem with these is that it is usually the valve guide in the head and not the valve itself that is the problem,

also ASP/Magnum valve springs are very weak compared to OS valve springs

Another situation is that Magnum/ASP parts quality control is terrible. I suppose their final QC is the person putting the engine together at the factory?

I ordered two valve sets from Hobby People for a 30 and the valves were cut to the wrong length and I could not use them. They must have been rejects from the assembly line at Sanye?
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Old 08-20-2010, 03:54 PM
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Default RE: 4 cycle lubrication

I think I'll keep running this engine 'till it goes out and then get an os or saito.

The engine is currently in my brand new H9 super stick. it's maiden flight will hopefully be monday. I'm hoping the power to weight ratio is good enough to start practicing hovering.

Am I being way too optamistic?

I havn't weighed the plane yet and I'm running an 11x8 prop......
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Old 08-20-2010, 09:21 PM
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Default RE: 4 cycle lubrication


ORIGINAL: a.bailey

I think I'll keep running this engine 'till it goes out and then get an os or saito.

The engine is currently in my brand new H9 super stick. it's maiden flight will hopefully be monday. I'm hoping the power to weight ratio is good enough to start practicing hovering.

Am I being way too optamistic?

I havn't weighed the plane yet and I'm running an 11x8 prop......



That engine should fly it well....however, if you really want to try hovering, I would suggest a larger diameter prop with less pitch, like a 12x6 or maybe a 13x5 or 13x4W

Your 11x8 would be better for speed...not hovering.
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Old 08-20-2010, 09:45 PM
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Default RE: 4 cycle lubrication

I ran a regular APC 13 X 4 and it did pretty good
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Old 08-21-2010, 06:54 PM
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Default RE: 4 cycle lubrication

Just picked up a couple 12x6 props. Gonna try them out. I'll also try out the 11x8 and a 12x8.

Decided to try and re grind the valve. I'll do it when I have time sometime next week.
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Old 08-22-2010, 09:15 AM
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Default RE: 4 cycle lubrication

a.baily. Use toothpaste, not valve grinding compound, you WILL grind away the whole valve. The best way that I found, was to CA the valve to the end of a pencil eraser, and use that. Cut loose and clean up when finished.

Les
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Old 08-22-2010, 09:41 AM
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Default RE: 4 cycle lubrication

I was planning on using the grinder attachment on my lathe. I'd be regrinding it just like full size valves. I'll only take about .0005- .001 off the sealing surface.
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