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4 Stroke Mystery - 6/22/2008 9:48:22 PM   
ZoomZoom-RCU



Posts: 471
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		OK, guys. I've been fooling with this issue for over three weeks and have gotten nowhere. Thought maybe some of the experts in here might shed some light on it. I've been having trouble with reliably hand starting my Magnum XL 52 4-stroke. Its turning (or poorly attempting to) a 11x7 prop. I'm using 10% nitro and hand cranking it with a chicken stick. Here's the wierd thing. It used to start (although sporadically) after a ridiculous amount of cranking, and run ok. My goal was to get it to start more reliably. It improved somewhat and, a few times it fired very easily from the back stroke...bumping it in the wrong direction and it firing on the kickback in the right direction, and that even on the first couple flips. I'm improving I thought! Riiiiight. Anyway, after a few runs (maybe 5) like this, it has stopped starting altogether. It will sputter and turn over a few times on the crank at best, and this very reliably, but never really start. Only sputter-tick over a few turns and die. I've tried everything. I pulled the valve cover and checked the gaps, you can get a shim of flashing aluminum in the gap. I don't have a gap tetser but it seems both gaps are the same, so they probably haven't moved. I tried all of the nuts and bolts to be sure nothings loose. All seems good. There don't seem to be any air/fuel leaks. My glow plug seems to have a touch of brown film, but I've cleaned it off with no improvement. I think its due to unburned fuel from all of the sputtering no-starts.Anyway, I'm stumped. You guys have any suggestions before I pitch it off a bridge?! This is my first foray into 4-strokes, and, as it stands, I may not be coming back.

TIA for the help!

ZZ.

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RE: 4 Stroke Mystery - 6/22/2008 11:09:24 PM   
The Ghost



Posts: 873
Joined: 3/18/2004
From: UlladullaNSW, AUSTRALIA
Status: offline 		First the prop is wrong (too small). Read the instructions that came with the engine and use the settings that are in it. Are you using an OS 'F' plug. When checking the tappet clearence you should only use the correct feeler gauge(check the INSTRUCTIONS) and only need to be looked at after run in. Some 4strokers will need an electric starter untill it is run in and high and low needles are set. Also you will need a tacho to set the max RPM as you will not be able to hear the peak.

Cheers

< Message edited by The Ghost -- 6/22/2008 11:14:25 PM >

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RE: 4 Stroke Mystery - 6/22/2008 11:52:44 PM   
ZoomZoom-RCU



Posts: 471
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		Sorry Ghost, I meant 12x7 for the prop. So what I'm using is whats recommended. And the glow plug is a 4-stroke plug, but I'm not sure if its the same as the OS-F you recommend. Will that matter? I have a miracle plug, for 2 AND 4 stroke I could replace it with. As for the rest I haven't altered anything from factory, so it should be ok. Thanks for the suggestions.

ZZ.

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RE: 4 Stroke Mystery - 6/23/2008 12:33:25 AM   
Scar



Posts: 2277
Joined: 10/1/2002
From: Peoria Hts, IL, USA
Status: offline 		Mine's inverted, in a World Models Ultimate 30. I prefer a 12X6 APC, and am using a Thunderbolt 4-stroke glow plug I got from Hobbyshack (now Hobby People.) And, I like using an electric starter, because I can't get at the carb to prime it.

The ones I've started by hand, I like to prime & then work the fuel a bit by turning the prop over briskly about six times. Then I turn it backwards up against compression and attach the glow driver. I let it sit perhaps 20 to 30 seconds, warming up the fuel/air mix in the combustion chamber, and then roll it 180 degrees forward direction, and slap the prop backwards. It hits compression, ignites and runs in the proper direction. (usually.)

If yours doesn't, start changing things, like the fuel jug, the glow plug, the fuel delivery system. There are engine guys who won't look at your engine on the plane, they want it on a test stand (where they can see & control the fuel tank & lines.) Might be a good idea to start there.

Good luck,
Dave Olson

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RE: 4 Stroke Mystery - 6/23/2008 12:55:23 AM   
ZoomZoom-RCU



Posts: 471
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		Thanks Scar. Thats an interesting proceedure, and I will try it. I'm new to 4-stroke so its all an unknown to me. To prime do you cover the exhaust and crank the prop? How many times? I've been blowing in the pressure return from the muffler till I hear it gurgle in the engine, then turn it through 4-5 cranks. Im worried about flooding it, but don't think I am cause it won't even try to fire unless I do this. I can't use an electric syarter in my config....so I'm gonna have to make it work somehow.

ZZ.

P.S. I think you have a clue in your proceedure there, cause I've noticed a tendancy to kick a bit more on the back stroke when its been allowed to sit a bit before cranking it. Hmmmm.

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RE: 4 Stroke Mystery - 6/23/2008 5:11:25 PM   
Rodney



Posts: 4782
Joined: 12/8/2001
From: FL
Status: offline 		The easiest way to prime is as you say here, cover the exhaust and turn the engine over (holding the prop firmly so it doesn't backfire and cut your fingers) a few times. Mine like to start a little wet but; if mounted inverted, be careful not to get a fuel lock or you may break or bend the con rod. When I use an electric starter, I do not even prime first, just put the igniter on and apply the starter. Most of mine, once warmed up or properly primed, will start with a simple reverse flick by grabbing the spinner between thumb and finger and give a sharp clockwise (backward) snap. It kicks and starts in the proper direction.

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RE: 4 Stroke Mystery - 6/23/2008 10:30:24 PM   
The Ghost



Posts: 873
Joined: 3/18/2004
From: UlladullaNSW, AUSTRALIA
Status: offline 		Check out Saito Setup I know that you don't have a Satio engine but the information is simmilar for all 4strokers.

Cheers

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RE: 4 Stroke Mystery - 6/24/2008 2:24:26 PM   
ZoomZoom-RCU



Posts: 471
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		Thanks guys for all the help. I've tried all the above for over three weeks with no improvement. All I can say is its a Magnum POS , and I am done with it. Guess in this case you get what you pay for, and the reduced dollar sign lured me in and I got bitten on this one. Sooooo, anyone here have any experience with the OS-56a? Easy to hand start? Run on 10% nitro? All my OS engines are great, so I'm thinking, go with proven reliability and ease of use. Any ideas?

ZZ.

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RE: 4 Stroke Mystery - 6/24/2008 3:36:55 PM   
cracker


 

Posts: 38
Joined: 7/21/2002
From: Blaine, MN, USA
Status: offline 		Sounds like your needle valves are not adjusted properly. Put them back at the factory setting and follow the break in procedure. This engine takes a little bit to break in. I have 1 and it runs excellent. You will need a starter for this engine. Run it as recommended and lean the settings according to the instructions. These engines IMHO are not a pos. I have several magnums and they run as well as more expensive ones. You will like it once it is broke in and adjusted properly.

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It's only bad if you can't fix it!

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RE: 4 Stroke Mystery - 6/24/2008 3:49:15 PM   
ZoomZoom-RCU



Posts: 471
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		Appreciate the attempt at rescuing Magnums good name, but it doesn't cut it here. I tried every needle valve combo possible including first and foremost thier factory settings repeatedly!! Annnd, what part of I CANT USE an electric Starter doesn't get across. So, since Magnums seem to be waaaaaay too finnicky to allow ease of hand starting, much less reliability in finding a needle valve setting that can be maintained......(or startable!!), I'm going in a higher quality direction, and recommend others do the same. Unless of course they have thiers mounted on a flying plank where they can electric start it and fiddle with the settings all day. I'd rather fly...thanks. My confidence in thier product is shot, and in addition to this, I now have to replace the bottom of the fuselage in a brand new AC where it spewed gunk and fuel from maybe 1000 failed start attempts. No thanks, I'm done. Perhaps I was just unlucky and got a lemon, even so...my 4th chance drawer is empty. The Os 56fsa is lookin pretty good right now.

ZZ.

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RE: 4 Stroke Mystery - 6/24/2008 3:55:46 PM   
khelsea


 

Posts: 79
Joined: 2/7/2005
From: Detroit Lakes, MN, USA
Status: offline 		I have one on my Cap 232, the second plane. It starts and runs excellent but I do use an electric starter. Follow this thread and give it time to breakin, you'll like it. Khelsea

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       Post #: 11

RE: 4 Stroke Mystery - 6/24/2008 3:58:43 PM   
khelsea


 

Posts: 79
Joined: 2/7/2005
From: Detroit Lakes, MN, USA
Status: offline 		And get it back on the engne stand till you get it figured out, you have something wrong and need to eliminate the possibilitys. Khelsea

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RE: 4 Stroke Mystery - 6/24/2008 4:01:30 PM   
ZoomZoom-RCU



Posts: 471
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		This has already been done. Its heading back to Magnum today, for the SECOND time, for repair...then I'm selling it. You got $120.00? it can be yours!!

ZZ.

Seriously

< Message edited by ZoomZoom-RCU -- 6/24/2008 4:04:59 PM >

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RE: 4 Stroke Mystery - 6/24/2008 4:39:13 PM   
TFF


 

Posts: 742
Joined: 10/30/2006
From: Memphis, TN, USA
Status: offline 		I have never had much luck hand starting a 4 stroke even though I see it done all the time at the club; 2 strokes easy. I only started my Mag .91 one time by hand as my old flying buddy was not with me and I was at a new club. They felt sorry for me and lent me a starter for the day. Every other 4 stroke I have I have never tried to hand start. That .91 is 7 years old and runs great, not the same quality as an OS or Saito but it is 93.5% as good. I think the secret to getting a 4 stroke to start by hand is to get it truly flooded, but I am too scared for my fingers and face to do that, and the ones who do hand start theirs seem to to it rather franticly not methodically.

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       Post #: 14

RE: 4 Stroke Mystery - 6/24/2008 4:53:49 PM