John Tee Posted June 17, 2020 Share Posted June 17, 2020 I have been setting up a Saito 125A four stroke engine today. Has never flown but has been run before as a short running - in exercise. Not sure if I have a problem or not. The engine runs nicely,plenty of poiwer, smooth and after a bit of fiddling idles and picks up nicely. I have used old fuel - age unknown, with 5% nitro 9% synthetic oil and I think the label says 8% but may be 5% castor oil. The query is that when running with the exhaust on the right of the model and pointing away from the model there has been a thick castor type goo over the left wing leading edge which appears to be coming from the cranckcase breather tube ( extended) as it was blown that way in the prop wash. Have I got a problem with maybe a piston ring letting by? I know very little about 4 strokes. I have some prosynth 2000 fuel which is purely synthetic I will try next time to see the effect. I have had the motor for some time but never finshed the model it was in until the lockdown. Trying to get the model ready to see if it will pass the noise test at the field in the next week. Any advise welcome , Thanks in advance. John Quote Link to comment Share on other sites More sharing options...
Concorde Speedbird Posted June 17, 2020 Share Posted June 17, 2020 No issue, mine did this when running in. It will stop doing it after more running. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted June 17, 2020 Share Posted June 17, 2020 Very little oil is actually used John, so put simply, if you put a lot of oil in, you will get a lot of oil out. I have a few Saitos from new, and they get fresh clean Laser 5% full synthetic fuel, and no oil of note comes out. Oil does come from the breather Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted June 17, 2020 Share Posted June 17, 2020 Dont worry it sounds fine . The only problem is the Castor oil. use up the fuel you have and buy synthetic based fuel with NO castor . As Denis in previous post says if a lot of oil goes in then it will come out . even with low oil content a little will/should come out of the breather Quote Link to comment Share on other sites More sharing options...
bert baker Posted June 17, 2020 Share Posted June 17, 2020 I had a Laser engine that came my way in a plane it had a small container pipes to the crack case breather to collect the oil I have removed this as I was told never to extend the breather as this may cause the engine to overheat Quote Link to comment Share on other sites More sharing options...
John Tee Posted June 17, 2020 Author Share Posted June 17, 2020 Thanks for the replies. That is a relief. I did wonder about the castor content so will not use that anymore.As I sadid above I do have some syntheitic so will use that from now on. Bert I only extended the breather as it is a cowled motor ( the head is in fresh air) so didn't want any oil dripping out of the cowl, I knew a small amount of oil would come out but didn't expect what I got today. The engine did get quite hot but I didn't ru it for too long. John Quote Link to comment Share on other sites More sharing options...
John Tee Posted June 17, 2020 Author Share Posted June 17, 2020 I should add that I was running the engine without the cowl for ease of adjustment. John Quote Link to comment Share on other sites More sharing options...
John Tee Posted June 17, 2020 Author Share Posted June 17, 2020 The tube extension was about 3 1/2 inches. Not sure how this would cause an engine to overheat though. John Quote Link to comment Share on other sites More sharing options...
bert baker Posted June 17, 2020 Share Posted June 17, 2020 As I understand it with no pipe on the nipple oil just gets blown out of th nipple and stays clear,, with a bit of pipe on it eventually the oil builds up in the pipe and a gloopy oily lump just goes back and forward in the pipe and doesn’t breath to atmosphere,, some of the heat will go out with oil Quote Link to comment Share on other sites More sharing options...
John Tee Posted June 17, 2020 Author Share Posted June 17, 2020 OK Bert I will remove it and see what comes out. John Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted June 18, 2020 Share Posted June 18, 2020 Posted by John Tee on 17/06/2020 20:26:24: The tube extension was about 3 1/2 inches. Not sure how this would cause an engine to overheat though. John All 4 stroke motors run Very Hot !!!!! John, especially the silencer Hot enough to injure you That is why getting up into cooling air is a good idea Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted June 18, 2020 Share Posted June 18, 2020 All my four strokes run with a tube on the crankcase breather to run the oil out of the fuselage. Mind you I did have to recently change the bearings on my 1986 (I think) Laser 75, but maybe that's a bad one as my similar vintage 61 is still on it's original bearings. Quote Link to comment Share on other sites More sharing options...
Jon H Posted June 18, 2020 Share Posted June 18, 2020 As Denis points out, engines get hot. I often get questions customers saying their engine is too hot. I ask how hot is too hot and they reply that its so hot they cant hold on to it after a flight. My reply is always, why would you want to hold it? You dont lift the bonnet on your car and give the engine a cuddle after a run! As a general guide model engines run at between about 80 and 120'c As such, you really should not be able to hold the engine after a run. If you can hold on to it after a run, its probably running well rich and wasting fuel. The oil as coolant argument is also kicked about but the amount of heat taken away by the oil is really not worth getting excited about and can be ignored. I agree with the other comments regarding castor, just dont use it. Laser 5 or techpower 5 are my go to fuels and both work extremely well in saito engines. Quote Link to comment Share on other sites More sharing options...
John Tee Posted June 18, 2020 Author Share Posted June 18, 2020 I won't use the castor fuel agin, I will keep it to free up several motors that are gummed up after using the castor fuel. Thanks again for the info. John edited for bad typing again Edited By John Tee on 18/06/2020 09:53:15 Quote Link to comment Share on other sites More sharing options...
Nigel R Posted June 18, 2020 Share Posted June 18, 2020 Surely, if goop is coming out the breather, then the breather tube is ok? With somewhat limited experience here (I've only ever owned one brand new four stroke) I would assume that the ring seal will improve after running in, to the extent where crank pressure is reduced and less gunk gets ejected via the breather? Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted June 18, 2020 Share Posted June 18, 2020 If you need to extend the breather tube more than a couple of inches then it should be enlarged. As already said a short piece that fits onto the nipple then a larger diameter that fits over that so oil can drain away . If narrow I/D tube is used then oil will simply bounce back and forth and an excess will/can build up in the crank case and in extreme cases can bog down an engine. The piston ring wont stop all oil passing to the crank case , its not supposed to as the engine rely's on this by-passed oil for it lubrication . Don't forget its a total loss system as opposed to a dry sum system used on bigger/full size aircraft engines or wet sump used on car engines Quote Link to comment Share on other sites More sharing options...
Alan Hilton Posted June 18, 2020 Share Posted June 18, 2020 I run mostly Laser engines and keep a stock of 10% synthetic oil fuel (southern model craft ) I have one Saito 180 which gets the laser fuel and runs with no problem and little mess . I use a short length of fuel tube to extend the crankcase breather to the edge of the cowl and have experienced no problems with this Alan Quote Link to comment Share on other sites More sharing options...
Thomas Nilsen Posted June 28, 2020 Share Posted June 28, 2020 I've got a Saito 125 in a Goldberg Ultimate mounted inverted - the engine that is. Always been running it on 12-15% nitro fuel with synthetic oil, lately using Optifuel 12%. It is the best engine I've ever had. Always starts easily and runs like a dream with a APC 16x4W propeller. The idle is superb and low and plenty of power. I've also got a piece of fuel tubing on the breather nipple about 10 cm long and never noticed any issues with it in the last 10 years I've been running the engine. - Thomas Quote Link to comment Share on other sites More sharing options...
John Stainforth Posted June 28, 2020 Share Posted June 28, 2020 Thomas. I have had the same experience with a Saito 125 for ten years in a Hangar 9 Funtana. I also use a 16 x 6 prop and 12 to 15% nitro fuel. The engine is side-mounted with a Pitts-type muffler. The piece of fuel tubing I have on the breather nipple is about 15 cm long, and I have never had a issue with that. Indeed, I hadn't realised that there was any issue with the length of the breather tubing. Quote Link to comment Share on other sites More sharing options...
J D 8 Posted June 28, 2020 Share Posted June 28, 2020 The only engine I have had suffer " bogging down " was an Enya 90 and it had nothing to do with extension pipe length. Took a while to find but it was that the breather nipple had not been drilled through fully and only had a pin sized hole. It would still run for five to eight min's before stopping. My Major Mannock also Enya 90 powered has an extension running all the way down the uc leg with no problem's. Quote Link to comment Share on other sites More sharing options...
Doug Moss Posted June 28, 2020 Share Posted June 28, 2020 Has anyone here experimented with feeding the crankcase breather back into the inlet tract? Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted June 28, 2020 Share Posted June 28, 2020 OS did, and it worked Quote Link to comment Share on other sites More sharing options...
Doug Moss Posted June 28, 2020 Share Posted June 28, 2020 Yes, I notice that they took it from the cam drive area, presumably so as not to bypass the gears and bearings? Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted June 28, 2020 Share Posted June 28, 2020 Have seen a few motors with a nipple tapped out by the owner, into the manifold but it is such a small amount of oil. Granted, even a small amount sloshing around the cowl is not desireable, but a short pipe through a hole is not so noticeable. Edited By Denis Watkins on 28/06/2020 10:00:30 Quote Link to comment Share on other sites More sharing options...
J D 8 Posted June 28, 2020 Share Posted June 28, 2020 OS looked to have dropped the idea from newer models. Quote Link to comment Share on other sites More sharing options...
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