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Author Topic: 2:17 Running with 10 cc in tank of a Jin M90. edited.. It holds 16 cc (ml) running nearly 5 hours!  (Read 292 times)

RedRyder

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I decided to give it a little test with a full tank.


I was able to get about 10 cc of av gas with mystery oil into the little tank and tube.


This has been modified to run a little slower. It was firing 28-30 times per minute for the first 10-15 minutes and then coasted a little more and fired just 24 -25 times per minute for the remainder of the run. The little engine free-wheeled 40 revolutions (plus or minus 2) between firings and fired once each time it hit.


This gave me a thoroughly enjoyable desk-top run while I finished editing and publishing the Coolspring video footage.


Even after 2 hours 15 minutes, it never even got warm to the touch. Highest temperature found was 88-90 degrees Fahrenheit (where the top of the head meets the hopper).


Gil

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My M90 tank held about 14ml Gil, and I was able to get just over 2 1/2 hours out of it on old stale Coleman fuel with just a few drops of MMO. Mine was hitting somewhere around 50 times a minute with very few double hits, and likewise ran quite cool for the whole time. I'd guess that if I could get mine down to hitting under 30 times a minute, it should be able to clear 3 hours on a tank, no problem.

You certainly have been fine tuning that little pup ...... and I'm still totally amazed at how well built these little engines actually are ... amazing!
"Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music: Music is THE BEST...   
Wisdom is the domain of the Wis (which is extinct). Beauty is a French phonetic corruption of a short cloth neck ornament currently in resurgence..."
F. Zappa ... by way of Mary, the girl from the bus.

Nick

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Very interesting Gil, what all has been done to yours for slower running?
Nick

St Paul Steam

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interesting endurance runs fellows, I guess I never tried to see how long they would run, but I have a show in about 2 months & this will be good to know. thanks for the information.
Bruce
St. Paul Indiana , USA

RedRyder

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My M90 tank held about 14ml Gil, and I was able to get just over 2 1/2 hours out of it on old stale Coleman fuel with just a few drops of MMO. Mine was hitting somewhere around 50 times a minute with very few double hits, and likewise ran quite cool for the whole time. I'd guess that if I could get mine down to hitting under 30 times a minute, it should be able to clear 3 hours on a tank, no problem.

You certainly have been fine tuning that little pup ...... and I'm still totally amazed at how well built these little engines actually are ... amazing!




Thanks for the info re 14 ml. I suppose I just thought it was full with 10. If it holds 14 ml, I had room for 4 more because I put in exactly 10 with a graduated syringe.

RedRyder

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Very interesting Gil, what all has been done to yours for slower running?





Removed 1 spring from the governor weights.
Retarded timing a little.
Used 100 LL aircraft fuel with Mystery Oil.


The aircraft fuel with higher octane burns slower than Coleman fuel so has a little less punch.
You can also stretch the governor springs a little at a time until you get the desired effect. This way you keep both springs.

Stoker

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14ml was just an approximate at the time, though it was measured with a graduated syringe also, but maybe not with an eye to true precision. So I'll have to say it was 14ml +/- with an tolerance factor of may 2ml .... YMMV.

I'll do a carefully measured fill-up this afternoon when I get back from my shoot. As this is a double shoot weekend I'm a bit busy just now, and will be leaving in a few minutes.

Heck, after I do a carefully measured fill, I might as well do another timed run too, and see if the two battery ignition has any effect on that.
"Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music: Music is THE BEST...   
Wisdom is the domain of the Wis (which is extinct). Beauty is a French phonetic corruption of a short cloth neck ornament currently in resurgence..."
F. Zappa ... by way of Mary, the girl from the bus.

Stoker

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Good info Gil ... thanks for posting that. I wonder if my old stale Coleman fuel also has a bit less punch?

I will add the caveat that you need to be careful not to overstretch your springs like I did. I stretched a little and didn't see any change, so stretched a little more and still didn't see any change, then stretched a little more and all of a sudden my throwout weights would no longer pull in against the hub, so the engine would barely run if at all. You can't really re-compress this type of coil spring effectively, so I made arches of them which were held in place with the clamping action of their mounting screws, thus making them somewhat adjustable by varying the amount of arch present. I'll try to post a photo to show what I'm talking about this pm.
"Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music: Music is THE BEST...   
Wisdom is the domain of the Wis (which is extinct). Beauty is a French phonetic corruption of a short cloth neck ornament currently in resurgence..."
F. Zappa ... by way of Mary, the girl from the bus.

RedRyder

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Good info Gil ... thanks for posting that. I wonder if my old stale Coleman fuel also has a bit less punch?

I will add the caveat that you need to be careful not to overstretch your springs like I did. I stretched a little and didn't see any change, so stretched a little more and still didn't see any change, then stretched a little more and all of a sudden my throwout weights would no longer pull in against the hub, so the engine would barely run if at all. You can't really re-compress this type of coil spring effectively, so I made arches of them which were held in place with the clamping action of their mounting screws, thus making them somewhat adjustable by varying the amount of arch present. I'll try to post a photo to show what I'm talking about this pm.


I know exactly what you mean by arching the springs. I have done it on other engines and my older blue engine from Jin.
If your springs are now too long to hang straight, You can cut them shorter and re-bend the ends where the screw goes. This way you can possibly unarch them. You can practice by trimming just one coil off. Might need 2 small needle-nose pliers for this. Oh yes, please trim off one end only.

RedRyder

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Jin tells me these M90's (ET1) hold 16 ML fuel.


So I filled my 10 ML syringe, then filled it to 6 ML and got it all in.


Now at 3 hours 20 minutes... still going but I think it must be getting close to the end. Ambient temp of the room is also warmer than yesterday.


Running a little warmer at 98 degrees F today and firing 28-32 times per minute.... a little more than yesterday.


Edit:  3:40 and still going.


Edit:   now 4 hours and still going!


Final Edit: The run is over at nearly 5 hours. It was just 4 minutes shy of 5 at 4:56 to be exact.


I was able to restart and run it for another few minutes by holding it upright with the spark plug pointing to the table top which allowed the last of the fuel to have the help of gravity to get it from the tube into the engine. Still not enough to call it 5 hours.


Gil



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Gil ... glad you took it to the limit as my attempted run this afternoon was a flop .... well mostly a flop. I can say that one fill of my tank got me well over three hours run time, but I did have problems that caused me to lose track of actual time as the engine quit on me a couple of times, and wouldn't restart right away. I was also not right there when it stopped, so don't know how much actual run time was lost, though certainly less than ten minutes each time. Can't figure out what the problem was/is as it stopped again somewhere near four hours and now won't start, but there is no air showing in the fuel line so I know it hasn't run out yet.

I got 14.6ml from a high quality glass medical syringe (B*D Yale) into the tank, but I also had the needle valve on the carburetor open 1/4 turn so some of the fuel I was putting into the tank may have been lost into the cylinder. It did take me half a dozen flips to get it to start and it obviously started up very rich. Another problem I had was that while adding in the MMO I was trying for 25 drops, but around 20 drops got a squirt that probably doubled the oil I put in the fuel, so perhaps my run problems were due to too much oil in the mix. That was the very last of my old Coleman fuel, so I couldn't rectify the MMO overdose in any way.

The first time the engine quit, I thought it might be a break in one of the wires, the way the thing bounces around could easily pinch a wire, but no ..... I pulled the spark plug wire and gave the engine a flip, and YOWWWIEEEEEE, nope not an electrical problem. So I pulled the plug to see if it was fouled, and broke it (Oops) as my wrench had no room to turn and my socket fit at a very slight angle that was enough to break the ceramic when torqued. The plug was not especially foul, with just a little black carbon showing, hardly anything at all really, but the plug was really wet. With a new plug installed it took right off, but stopped again within an hour.

Another problem with my endurance run today was that I did a little tweaking of the springs on the counterweights and even though that did seem to slow the engine down some, giving me about three hits every five seconds, it also caused it to double hit some and even triple hit once in a while, so clearly not an optimum situation. Still I'm certain that I did get something over three hours run time (likely well over) and the tank isn't empty yet.

I'll try again later and see what I can do with fresher Coleman and perhaps a bit less MMO, and perhaps messing around a little with the timing.

Congratulations on your very nearly five hour run!!!

ps: Yes I fully realize I can trim the springs back to a shorter configuration, but thought I'd play with the "arch adjustable" concept a bit first, before I go whacking on them. Shortening them even one coil does make them less elastic (stiffer) so is not ideal. May see if I can get a few spare springs from Jin at some point, so that I can get back to a nominal configuration and have more options.
"Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music: Music is THE BEST...   
Wisdom is the domain of the Wis (which is extinct). Beauty is a French phonetic corruption of a short cloth neck ornament currently in resurgence..."
F. Zappa ... by way of Mary, the girl from the bus.


RedRyder

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Hi Daniel, I know it zapped you but you still might try a fresh set of batteries. It makes a difference. My batteries had been in a while and it started to act up about 3 hours into the run. I turned it off long enough to replace the 3 batteries.


Also it doesn't jump around because I run a bungee cord across the desk over the top of it.


Gil

RedRyder

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Nick

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Quote
I pulled the spark plug wire and gave the engine a flip, and YOWWWIEEEEEE, nope not an electrical problem

Yes these really do send out one heck of a spark!  :o

Quote
I hope this is helpful.

Haha on the spark plug!  :D

Have never really messed much with mine yet, but home to get it running as well as yours in the video  8)

I know a few have recommended running on two batteries, but are you running on three all the time Gil?
Nick

 

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