Dear All,

I was planning to purchase an OS 4 stroke engine. It will likely be either of FS-71A or FS-81A. Only Magnum is otherwise available to me. Someone at the field had earlier told me that I must not consider running 4C engines with plain castor as the performance will not be good. Just wanted to know if this is correct. I will be using 20% castor home-brew fuel with no nitro initially

Ameya

I run all my engines (2S/4S) on a similar fuel mix, 20/80, and they all like it. Using synthetic as part of the total oil content wil make the engines rev a little more, say around 200~400rpm.

Don't worry, just fly

Full castor is OK. It will leave your engine a brown mess on the outside, but it is a good lubercant for the engine. Some nitro would help though, especailly at idle. The engine may be a bit harder to tune without it, but there are a lot of guys that do run FAI fule in their four strokes. I would reduce the castor to18%. The four stroke doesn't have the raw fuel going though the bearings and such but is lubercated by blow by from the power stroke. Most of what is in the crank case and elswhere is just the lube. The castor will portect the engine in the event of a lean run.

If you have access to Model Airplane News magazine, the October 2009 issue has a great article on oil in glow fuel. I can't locate the article on line though.

Don

My experience is the following.

I have a Thunder Tiger F-75S....the first 5 liters of fuel were 22% Castor oil, 12% Nitro and the rest Methanol.... and ran very good.

I've tried coolpower 5% and the engine didn't like the fuel at all!

I tried another fuel with 15% syntethic oil and 12% nitro and the engine didn't produce as much power as with the castor oil...

The problems you may experience running castor oil on 4 strokes are normally not related to performance, but related to carbon build up on the exhaust valve....you may have to clean it regularly (de-coke).

You don't have to use 20% neither... With about 15% Castor oil you will be fine.

The engine may just run fine without nitro as well...maybe you won't get a very low idle or super clean transition...But I haven't tried my 4 stroke without nitro.... I've run all my 2 strokes always without nitro.

Just give it a try! it won't hurt anything in the engine you plan to buy!

I'm a little concerned about castor oil and the small vent passage in the OS four strokes. If left to congeal this hole may or may not clear up after taking the engine out of storage. A little preventative maintenance would be in order. Any glow engine has no problem with castor oil as a lubricant.

So I guess there is really no difference?

Also, what care does the 4C engine require as compared to the 2C engine. Personally, I always afterburn all my 2C and clean them externally regularly. Never use after-run oil though. But "valve clearence adjustment" and "de-coking" are all new terms to me

Ameya

I am running wildcat 20% oil 20% nitro, all of my four strokes love it.

Sure they love it

But not everywhere such fuels are easy to get...and their costs are prohibitive....

Now That I'm living in germany I can get nitro, at a reasonable cost....

Back in Colombia, there is no way you can get nitro.... and a gallon of omega 5%...imagine like paying 60 Dollars for a gallon... Sometimes no nitro is the only viable solution!

$60 a gallon!!

Other than my YS motors, I use castor in everything...2 & 4 stroke. Always has been Omega or Wildcat.

The YS gets Powermaster YS 20/20...don't quite know what the blend is.

Articrider....what I mean is an analogy...

If I talk in Colombian Pesos... a FAI gallon would cost me about 14.000 pesos....if I buy a gallon of omega 5% nitro it would cost me about 45.000 pesos....and 15% about 68.000 pesos.... now go and think how would it be for a 20/20 fuel...

For us the USD is very unstable... but lets say about 2000 pesos for a dollar... and what you normally buy with a dollar (let's say a coke) you buy with 1000 pesos...so you have an idea how expensive is the hobby for the people in my country (about 2 times more expensive than in the usa)....and how expensive is fuel with nitro!!

Here in Germany I paid 37 Euros for 5 liters of 12% nitro and 22% castor oil....

The point is...Nitro is very expensive in the other countries.... Syntetic oils are not cheap....and castor oil is normally readily available and cheap...and maybe cheaper than in the USA....maybe not the best refinement quality, and may gunk more...but works...



Now going back to the original question....I was trying to point out...that yes...engines run very good with nitro...and the guy wants to know if the engine will run with castor oil and no nitro.... and I think that it will run ok, since the engine is a 4 stroke...he has to pay attention the maintenance...like checking the exhaust valve for carbon buildup....and use after run oil if the engine is going to be stored

A couple years ago, an old flyin' buddy (he's 80 and kinda old fashioned...likes a castor based fuel ) and I tried an experiment and ran his Saito 1.80 on an all castor fuel. On about the third gallon the exhaust valve started sticking...the stem was varnishing up. We first noticed a problem when occasionally, it had no compression (the valve was hanging open a bit from time to time ) gradually the problem got worse, until we got fed up with it, so...

I disassembled the jug and cleaned the valve (de-coked or de-varnished what ever ya wanna call it ) and it ran good as new.
We quit running it on all castor though, and went back to powermaster std. sport fuel...which is 18% oil (2/3 synth and 1/3 castor )

Both fuels were/are 15% nitro.

Global Hobby has quite a few of their product manuals online http://www.globalhobby.com/review/reviews.asp

This is the direct link to the Magnum .91 four stroke manual http://media.hobbypeople.net/manual/210970.pdf On page 3 they specifically recommend castor oil, mixed with synthetic. There is definitely nothing wrong with using pure castor oil as your lubricant.

Page 8 discusses adjusting the valves and has a drawing. All brands are pretty similar so this manual can be a reference for any of them.

I mix my own glow fuel, and have done so for 30 years, the only thing with straight castor and 4 strokes is it requires more maintenance due to carbon build up around the exhaust port and piston ring. With regards to performance, I find that all of my engines run better on 100% castor lube fuels, though I don't have any exotic type engines, i.e. no ABC, ABN, and AAC. In fact Ken Enya still recommends a straight caster oil fuel mix for all his engines including 4 strokes. The nitro content will give you more drama though, you may need to increase the compression and or use a hotter plug for a reliable idle, and most carbies are set up for nitro so it will have a negative effect on the low to high speed transition.

This is an old Enya 46-4C with 10% nitro and nil nitro, but both are running straight castor oil...

http://www.youtube.com/watch?v=xHYmE4NGEzY

http://www.youtube.com/watch?v=O6q358B260I

OK, I said I wont use nitro initially, but may be later. I am currently using fuel with a conservative 5% nitro on my 2C, having flown for 2 years initially without any. However, I would like more details on what maintainence activities are required for 4C. Can you give me some directive on the same with OS? This will be the first time I will be using 4C and I can but 2 Nos 55AX in the same price as one 72Alpha, so if it is too troublesome, I could stick to the 2C

Ameyam

About the only special maintainence you'll have to do (with the O.S. 4 stroke ) is clean the exhaust valve from time to time.
It's possable to clean / unstick it with spray carburetor cleaner...but that is just a temporary solution...the best way is to remove the head, then the exh. valve. I use an x-acto knife w/ a very dull #11 blade as a scraper to clean the carbon off then a scrap of worn 1000 grit wet/dry sandpaper and a drop of light oil to clean/polish the valve stem.

If you would need help disassembling a 4 stroke head, we will give you help when required...you can also do a search on the subject in this forum (it's been discussed numerous times previously )

I run everyone of my four cycle engines (and that's a lot of them) on straight 20% castor oil fuel with 10% nitro. Never have a problem and seldom if ever get rusty bearings.

Klotz KL-200 and KL-100 are available through Tower. As I see, KL-100 is a castor synthetic blend while KL-200 is pure synthetic. Should I be considering either of these for brewing 4c fuel? What I would be doing is mixing the contents (0.946L) with about 3.5L of mehanol and 250ml of nitro (5%) and 250ml (5%) plain castor. This will give me best of both worlds at a relatively affordable price.

What say?

Ameyam

PS: Cant obtain pre-brew fuel as it cant be air shipped

I would buy oil from either Morgans Fuel or Fox Manufacturing before I spend lots of money on Klotz oil. It's good oil, but cost way more than it should, and it is no better than Fox or Morgans oil.

I would too, but they are not available either

Ameyam

my OS, THUNDERTIGER, AND MANGNUM 4 STROKES all run on morgan omega, which is a castor/synthetic blend. All run fine and just an occsional clean up of the muffler, is a small price to pay for castors added protection.