Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines
The Regular Stuff: Chat, Buy, Sell, Off Topic, etc. => General Discussion - Scale Model Gas Engines - Hit & Miss - Throttle Governed - Non-Compression – etc => Topic started by: Jim on October 15, 2020, 09:20:32 pm
-
I’d get off the two stroke oil if possible. That’s the soot, just like you’ll get on the tail pipe of a two stroke bike or leg of an outboard. I’m not seeing much of it from my M91 using a fair bit of marvel mystery oil. Bog standard hydraulic fluid would also work. It’s designed for fairly high heat, high pressure in applications such as high speed hydraulic pumps and rams subject to far worse abuse than our engines. It will leave a bit of slippery slime, but not black, and won’t gum up in storage. A hint of how well hydraulic oil handles combustion. I’ve used it as a bore preservative inside black powder guns, and after a good post firing swabbing, they’re still oily.
-
Up until my ignition black box packed up, my M90 engine ran faultlessly on both zippo, ordinary unleaded petrol and a mixture of both. I don't think fuel is at the root of Raphael's problems with his engine. **
The variables that decide whether an engine will run are:
Compression
Fuel/air mixture
Proper energy of spark
Spark timing
Valve timing
Free movement of engine parts (ie not binding up and absorbing all the energy).
I don't think there is anything else that can stop a working design from working.
My M90 worked great, then it didn't when the ignition unit started to fail. The failure may have occurred because while I was trouble shooting a sooted up spark plug, I may have inadvertently spun the engine over without the spark plug body properly earthed to the engine, because I had the plug outside while I was looking at the spark energy to diagnose the sooted plug. This leaves the HT energy to make its way back through the ignition unit electronics to ground and is a common cause of breakdown and failure in electronic ignition systems. Having been brought up in the robust era of contact breakers and tough as iron coils, I didn't take account of this inherent weakness.
** EDIT.
I have run a little two stroke oil in my fuel - varying from about 20:1 when it was brand new, to about 40:1 after it had run a little while. Mine spits out carbon coloured oil too.
-
Hi Jan, the Marvel Mystery Oil I use won't gum up so no worries on this end either.
That said, thank you for the info on the no oil added.
-
I admittedly don´t own a M92, but my M90 have not seen a single drop of oil/lubricant in the fuel, and after more than 2 cans of Zippo fuel, i have noticed absolutely no difference in running characteristics or output.
Since the engine runs quite cool and wet from fuel on its own, and the pistonrings are made of rubber/nitrile, little to no wear is expected in the cylinder.
Personally i prefer this to avoid any chance of gum forming during longer storage, over the slight inconvenience of having to change a very cheap rubber-ring...which by the way will decay and stiffen up over time on its own anyway, nomatter if its greased up by the fuel or not.
-
To get the oil away from the engine, I bored a hole straight through the front of the muffler and plugged all 4 holes.
And now you have a clean engine, but oil spray all over your shirt ;) :D
-
Hi Jim, we just got back from 4 days at the Coolspring Power museum.
Regarding your too much oil question.... You do not have too much. Oil should pass through the engine. As long as you are using a naphtha based fuel and plenty of oil, the O-ring will last a long time. Since I started mixing fuel a bit rich with oil, I have not yet needed to replace an O-ring.
To get the oil away from the engine, I bored a hole straight through the front of the muffler and plugged all 4 holes.
Or... you could replace the muffler with a short straight brass tube about 1-1 1/4" long.
Wither way the engine will stay a lot cleaner.
Enjoy!
Gil
-
Hard to say how long the O-rings may last. It seems to be the consensus that only one is needed, so you automatically have a spare right there.
I have broken a spark plug myself, which I found to be very easy to do by mis-aligning a slightly oversize long socket, and putting a little torque on it. They are rather delicate me thinks!!!
Properly handled, they'll probably last a lifetime though, I just screwed up!
Still, it probably is best to have a spare around, just as a bit of Murphy prevention if nothing else!??! ;c)
-
How many hours do you all think these are good for? Is the easily replaceable 'O' ring the thing that cops the wear and tear?
How many hours have you logged?
Spare spark plug a good idea to have on hand?
-
Looks like you got a good runner there 8)
I don’t have this model, and your videos definitely making me want to change that!!
LOL....I'm well pleased to be able to return the favour :)
-
Looks like you got a good runner there 8)
I don’t have this model, and your videos definitely making me want to change that!!
-
Yes presently Raphael I don't want to change anything until I know a lot more about it.
I've been reading through all the threads in this section of the forum and picking up a lot of info from other members.
-
Bonjour Jim,
If your engine work, ad it does well, DON'T TOUCH ANYTHING ;)
On my side, I was suggested to use Zippo lighter fuel instead of Unleaded 98, I will do that.
-
Raphael, I haven't touched the spark plug or carburetor needle. Its as it came out of the box.
I'll have to read a bit more about the carburetor needle until I'm game to touch it.
-
Bonjour Jim,
Be sure I will try Zippo fuel as your experience is quite positive. I like sharing my experience to help people who could live the ssame situation, that means I sometimes share mys frustration.
Then people like you and also Jin come to help me and generally, I finally succeed.
Did you check the spark plug ? Did you modify / check the needle screw adjustment before its first start ?
-
Bonjour Jim,
Very interesting video, your one seems to run perfectly with Zippo gas when mine is awfully capricious with Uneaded 98. I will try with your gas.
Raphael, I have read of your woes and frustrations. I would try some Zippo lighter fuel and see if that remedies the troubles that you have had.
-
Bonjour Jim,
Very interesting video, your one seems to run perfectly with Zippo fuel when mine is awfully capricious with unleaded 98. I will try with your fuel.
-
LOOKS good!Jin
-
Jim's Hit & Miss Engine M92
Having a lot of fun with this engine since getting it yesterday.
How's it running?
https://youtu.be/PIcuH9E2TVw