Oily glow powered models

[TartanMac]

These are the filters I have on hand they are both the same brand but you can see the size difference the Saito is a 1.80 with a 1/8 scale Hyper ST PRO Air filter. The small engine is an RTR Hyper 10 TT engine with its Air filter attached without the 2 sponges in it. Modelsport and other places have loads of filters. I was going to use one too to keep it clean but also I wanted to see if it would be a little quieter as I hate any drumming or plastic vibration noises just sounds cheap. If you don't know if your air filter gets soaked it can richen up the mixture I was going to line the tube with foam to stop it running into the filter element. Easy fixed though just take the element out squeeze it in a paper towel job done.

[charles aldous]

Thanks Mac, the air filters look interesting, but no room in this particular model's cowl. The prop on question is actually 12 x 7. I'll tune the engine per John Harper's method and report back peak and idle rpm's achieved.

Thanks all for interest.

[Gordon Whitehead 1]

@ Peter Miller

Hi Peter, is that a 4-stroke in Peggy Sue 2, and if so, how do you keep the crankcase breather oil off the model?

@Charles Aldous

Hi Charles, you haven't mentioned whether the rear of the prop ends up coated in oil residue after a run. If that's the case, then it's likely to be caused by oil leaking through the front bearing and being flung out along the prop blades, as well as coating the inside of the cowl. As the engine is secondhand, perhaps a previous owner replaced the crankshaft bearings with non-Saito ones which were a bit slack on the shaft, or perhaps he didn't fit sealed bearings. Either or both of these acts would result in crankcase pressure blowing oil out of the front bearing housing.

Gordon

Edited By Gordon Whitehead 1 on 01/11/2017 19:14:22

[charles aldous]

Thanks Gordon, no oil on prop and as far as I could tell the original bearings.

[Steve Hargreaves - Moderator]

Charles, did I read in one post that you had sealed the crankcase breather & in another that you had connected the breather to the muffler?

Both options are, I would suggest, not a good idea...the engine needs the breather to be open to atmosphere to a) equalise the pressure in the crankcase during each stroke & b) to get rid of excess oil.....

A pipe from the breather should be routed to just clear of the fuselage & left open or I have seen it piped into a small container to collect the excess oil. This container is emptied every couple of flights or so...

[Denis Watkins]

Sport on Steve

Crankcase Vent: Check that the crankcase vent nipple is tightly attached. I once had one that was loose.

IMPORTANT !! The crankcase vent must be kept open to the atmosphere. This is NOT a pressure tap. It should not be connected to the fuel tank. Its purpose is to allow excess crankcase oil to drip out and it must never be sealed. It is convenient to connect about 4 inches of fuel tubing to this vent so that excess oil drips can exit outside the model; the fuel tubing is also useful because it is easy to squirt after-run oil into the crank-case through this tube

[charles aldous]

Hi Guys and thanks for all the comments thus far: I will update as follows:

1. I had the cowl off on Thursday and re-tuned the two mixture valves. It now peaks around 9300 rpm and I can a great transition and a spretty smooth idle at around 2200 +/-.

2. Whilst running with the cowl off I found the cause of the oil slick, see attached pics. It's not coming from the carb as I could clearly see no spit at all. It is coming from cam gear housing, so I will replace the gasket and hope that fixes it. However the gasket set is out of stock at Macgregor so any ideas?

3. Just for info, the breather has always been open to atmosphere, I have just moved where the tube is fixed in efforts to reduce the oil hitting the fus.

4. Whilst zero oil getting past the front bearing I intend to replace the bearings anyway whilst the engine is apart

[Peter Miller]

Posted by Gordon Whitehead 1 on 01/11/2017 19:13:50:

@ Peter Miller

Hi Peter, is that a 4-stroke in Peggy Sue 2, and if so, how do you keep the crankcase breather oil off the model?

@Charles Aldous

Hi Charles, you haven't mentioned whether the rear of the prop ends up coated in oil residue after a run. If that's the case, then it's likely to be caused by oil leaking through the front bearing and being flung out along the prop blades, as well as coating the inside of the cowl. As the engine is secondhand, perhaps a previous owner replaced the crankshaft bearings with non-Saito ones which were a bit slack on the shaft, or perhaps he didn't fit sealed bearings. Either or both of these acts would result in crankcase pressure blowing oil out of the front bearing housing.

Gordon

Edited By Gordon Whitehead 1 on 01/11/2017 19:14:22

Hi Gordon

Yes, ot is a four stroke, an OS FS 40 Surpass.

I am afraid that the breather just vents straight into the cowl. There is the faintest smear of oil over the first couple of inches of the belly of the aircraft. The oil drains out of the needle valve hole. IT works

[Peter Miller]

Posted by charles aldous on 05/11/2017 11:36:36:

2. Whilst running with the cowl off I found the cause of the oil slick, see attached pics. It's not coming from the carb as I could clearly see no spit at all. It is coming from cam gear housing, so I will replace the gasket and hope that fixes it. However the gasket set is out of stock at Macgregor so any ideas?

You can easily make a new gasket with thin copy paper.

Take the cam box off, moisten the face with oil, just a smear. Press the paper onto it to mark a perfect pattern. Cut it out and you have a gasket.

We always made gaskets for two strokes this way and two strokes must have a perfect seal on the crankcase or they don't work well.

If you want to be really fussy you can buy very thin gasket paper or possibly scrounge some from a local engineering works

[Gordon Whitehead 1]

Posted by Peter Miller on 05/11/2017 12:15:09:

Hi Gordon

Yes, it is a four stroke, an OS FS 40 Surpass.

I am afraid that the breather just vents straight into the cowl. There is the faintest smear of oil over the first couple of inches of the belly of the aircraft. The oil drains out of the needle valve hole. IT works

Thanks Pete. That sounds like a good way of localising the oil as a dribble on the fuz underside, so that it doesn't spray the entire underside back to the tail.

[Gordon Whitehead 1]

Hi Charles,

I'd follow Peter's advice as Saito spares can be out of stock for ages. For years I looked for Walbro carb diaphragm kits to hold as spares for my two 9 year old Saito 36cc petrols. Neither Macgregor nor Horizon Hobby in the USA ever had them. As it's a special to type model engine carb the items aren't available from Walbro dealers. Three weeks ago I was surfing MacGregor's website and nearly fell off my chair when I saw that they had two diaphragm kits in stock. So I got 'em both, the carbs are now like new again, and MacG are out of stock again.

[TartanMac]

Might want to measure the thickness of the original gasket as the saito has fine teeth on the cam drive gear and the clearance of the teeth is dependent on the gasket. Too thin it will be tight and wear too thick you risk them slipping. I would still just make a gasket though just get the thickness right.

[charles aldous]

Found online the guage of gasket to be 0.2mm and Just Engines are sending me a 300 x 400mm sheet for £5 posted. Let's hope this will cure the oil slick.

Thanks once again for all the input.

[charles aldous]

I made new gaskets for the cam drive gear housing and rocker covers as well and a quick test run on Friday showed no oil leaks.

Thanks to all.