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Old Nov 16, 2012, 05:15 PM
Complete RC Idiot Savant
The Netherlands
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Originally Posted by Gluehand View Post
After use, particularily before any "storage", turn the engine until you just about feel the compression.....this indicates that both valves are closed.
This way both valves will be forced to "unstick" at next start attempt...

This is a great routine with all single-cylinder 4-strokes....since I learned this trick ages ago, I have practised it with motorbikes, lawn mowers and model engines...never a stuck valve ever since...

Can't really believe this is a cure for a problem that actually exists, because the consequence invariably is, that multicylinders do have the occasional sticking valve, and I can not say I have EVER, in 20 years of professional engineering, as many years of motorcycling, more so in modelling, and general messing around with engines of very various configuration and fuel source, encountered a sticking valve, not even on the Engines operating on Heavy Fuel Oil that I work with professionally. And you wouldn't believe what kind of dirt buildup these engines can have in the intake and exhaust channels....

Brgds, Bert
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Old Nov 16, 2012, 08:36 PM
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The windy west coast of Sweden
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Quote:
Originally Posted by Brutus1967 View Post
Can't really believe this is a cure for a problem that actually exists
Of course it isn't.....I posted this as a slightly off-topic, general hint on single-cylinder 4-strokes, as I find this practice beeing basically a good thing...

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Old Nov 16, 2012, 09:25 PM
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United States, WA, Lynden
Joined Nov 2004
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that lil 4 stroke ring is prolly fine.....im thinking the lack of compression is a stuck valve. they do not like to move to well after sitting for a extended period, pretty weak springs. flush it with fresh fuel, warm it up with a heat gun, not hot, just 110 or so good and warm, see if you have compression then. been thru this many times with four strokes that have sat. if a castor oil content was used, I pretty much gaurrenty thats your prob.
I thought the 2 stroke 40's were abc.... no ring involved.
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Old Nov 16, 2012, 09:42 PM
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white lake michigan
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Quote:
Originally Posted by Brutus1967 View Post
Can't really believe this is a cure for a problem that actually exists, because the consequence invariably is, that multicylinders do have the occasional sticking valve, and I can not say I have EVER, in 20 years of professional engineering, as many years of motorcycling, more so in modelling, and general messing around with engines of very various configuration and fuel source, encountered a sticking valve, not even on the Engines operating on Heavy Fuel Oil that I work with professionally. And you wouldn't believe what kind of dirt buildup these engines can have in the intake and exhaust channels....

Brgds, Bert
I can say it happen's I just had a four stroke stick a valve at the beginning of the year. I left it stand on its spinner over last winter. I had no room so I left it like that and didnot oil it before storing. I flew it a few times then went to start it and nothing. I thought it was the plug so I changed it and nothing so I pulled the valve cover and watched as I turned it over. I forgot which valve it was but it was stuck open so I rinsed it down with a bit of fuel and hit the starter to it and watched to make sure it loosened up. I also agree they do not have much compression while shut down. I know saito's are better when not running but this was a magnum and it has very lttle compression. And it is only two years old and only a gallon threw it. So I didn't think it would stick a valve when it was almost like new. I could see if it were old and all crusted up but I guess it happens from time to time.
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Last edited by unclecrash; Nov 16, 2012 at 09:58 PM.
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Old Nov 16, 2012, 09:46 PM
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white lake michigan
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On the OS 40 I have not seen a ringed one. You should be able to fire it right up. If anything throw a new plug in it and a bit of fuel in threw the plug hole will get it going quick. Just a dribble though. You don't want to hydrolock it and chance bending the rod. Chances are on the 2 stroke if it is a good plug and still won't fire pull the needle valve and hook a piece of fuel line and blow through it and make sure the the tiny hole isn't plugged in the spray bar.
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Last edited by unclecrash; Nov 16, 2012 at 10:08 PM.
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Old Nov 17, 2012, 11:00 AM
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Devon,UK
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stuck rings

My OS is an OS Max 40 SR. I bought it eons ago in the USA when I worked over the border in Canada. It has a ring and runs very well.
It is now ok after two days soaking with fuel down the plug hole. Thanks for the help. I will take a look at the 20 4Stroke in the near future. Got to get flying with the 40 first.
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Old Nov 17, 2012, 03:32 PM
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white lake michigan
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Next time how about posting the motor specific's at the start of the thread instead of having everyone guessing what motor you are trying to fix. It would help heaps in getting the help needed. Instead of having to speculate and wonder what you have,Im sure most know the four stroke is ringed but most OS 40 two strokes you see people asking about are the cheap non ringed motors.
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Old Nov 27, 2012, 03:00 AM
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Israel, Ramat HaSharon
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I had an HB.40PDP, which did have a Dykes ring.
It made great power; out-revving Webra, OS and ST engines of the day.

The Pipe intended Blitz model did use a normal ring, however.
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Old Nov 27, 2012, 07:37 PM
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Adelaide, South Australia
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Quote:
Originally Posted by franciscan View Post
My OS is an OS Max 40 SR.
By sheer coincidence right now I'm in the process of getting a ring for one of them from Frank Bowman. There are two versions of this engine, the first uses a standard type pinned ring while mine (second version) uses an unpinned Dykes ring. I think the main difference between them was that the first version used a barrel type shut-off (for pylon racing) while the later one just had an enormous CL type venturi.

Another engine I'm getting rings for is a Taipan 61 which I was given a couple of weeks ago and probably hadn't been run for 20 or 30 years. Both rings were stuck tight in their grooves but one simply refused to unstick no matter how much I soaked it in acetone or heated in the oven and it finally broke. Frank has never made rings for one of these so I've had to send him the piston and liner but, being new to him, the first ring is free .
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Old Nov 27, 2012, 11:43 PM
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Lucky devil.
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