Hi, I'm new here so i hope I'm posting in the right area. I have a old Masport Iron Horse motor mower that was running up until a few months ago when the pull start cord spring mechanism unravelled, I finally got round to fixing it but now there is no Spark when i pull the cord with the spark plug out. any suggestions what it might be ? thanks
We need more information on the mower. Is there a plate saying what make and model the engine is? It sounds as if the magneto has been disturbed when you worked on it - perhaps something has happened to the kill wire. Did you remove the magneto? If so, there is a bigger range of things that might have happened. However to get started we need to know something about the engine.
Hi, Yes a little riveted plate on the motor says model D 4019 serial 890720 and on the body it says SER NO RC 610945 model 5. excuse my stupidness what is the magneto is it the magnetized side of the flywheel or the green thing that the other end of the spark plug cable is plugged into. it has 2 wires coming out of it one is attached to the screw and goes into the green thing the other comes out of the green thing under the flywheel and out of site cant see the other end.if the green thing is the magneto then i unscrewed the 2 screws to look at the contacts to see if they were dirty then put it back together. I don't know where the kill wire is. sorry as i said i am new to this but determined to learn more about small motors. I haven't removed the flywheel. Thanks
No problem, we are all here to gain experience and talk to each other. The magneto is the unit the flywheel magnets move quickly past, thus generating electricity in the magneto's coil. There are actually two coupled coils, one to generate a strong current at low voltage, and another, coupled coil to step that up to 10 to 20 thousand volts to make a spark. The diagram below shows a breaker-point magneto. Most modern ones use an electronic switch instead of a mechanical one, to achieve the same result. We need to think about what you may have done that stops your magneto from working. The first point is, how close to the flywheel did you put the exposed metal part of the magneto when you reinstalled it? It needs to be parallel to the surface of the flywheel, and about 0.012 inches away (the thickness of a visiting card). Second, did you earth the ground connection of the magneto (usually under one of its mounting screws)? Third, what did you do with the kill wire (not shown in the diagram, it is a wire from the bottom of the coil primary, just above the points - when that wire is grounded, it kills the ignition stone dead, which is how you switch off the engine when you need to stop it)? If you connected the kill wire to ground, that explains your problem.
Hi Grumpy I feel a bit stink calling you that considering your being so helpful. OK now i'm getting the hang of the the names. the magneto exposed metal parts are about the thickness of a business card or less away from the flywheel but there is no adjustment so the gap is set(old mower)yes the grounding wire is under one of the screws and i put that back as it was. now I know what the kill wire is its on the other side of the engine i haven't touched that yet as i didn't know what it was. On this mower it has the on/off knob on the engine cover and the on/off knob has a dual purpose as it is also the primer for the petrol. So if I'm guessing this right the other wire on the magneto that disappears under the flywheel must go to the on/off knob. and it is screwed to the frame, I just had a look with the on/off knob in place(it is a long piece of hard blue plastic 115mm long with a spring on the outside and a flat piece of metal at the base)when this is in the off position the metal at the base touches the kill wire screw. the kill wire on each end looks ok but for me to see the rest of the wire i'm going to have to take off the flywheel. I wish i could take a picture and add to my post but don't know if you can do that. Thanks for your continuing help Pete
Pete, I chose the name grumpy, so I can hardly object to anyone calling me by it.
It sounds as if you understand the layout of your magneto, so the next step is to check some basics of its operation. We need to know if it is an electronic type or a breaker point type. If it has points they will be fairly close to the crankshaft, and are just two flat pieces of platinum, one of which is moved up and down by a cam (bump) on the crankshaft, so they are usually inside the flywheel on small engines, especially 2 strokes. You said previously that you looked inside the magneto without removing the flywheel, and found some contacts. This is a bit worrying because if you opened up an electronic magneto and disturbed some contacts, there might be a problem now getting it to work again. On the other hand, your wire that goes under the flywheel might go to a set of breaker points inside the flywheel, and since you haven't had the flywheel off, that probably isn't the problem area. Can you post a picture of the magneto and tell us more about what you did and what you found, when you opened it? This is the most likely location of the problem.
To post a picture, put it in some convenient directory on your hard drive then return to this thread and push the "Switch to Full Reply Screen" button below the Quick Reply box. When the more detailed reply screen appears, push the "File Manager" button below it. Press "Browse", navigate to the picture you have just stashed on your hard drive, select it, press "Add File", then when it has loaded, press "Done Adding Files". Type in your message text as usual, then send it to Outdoorking in the normal way. The photo will appear below your message.
I don't understand the second picture. I see a button which pushes another button located below it. I don't know what the object below the top button is. If it is the top of the carburetor, that could be a flood button. You would push it before cold-starting the engine, and hold it down until fuel came out somewhere, indicating you had succeeded in flooding it. Then you would switch on the ignition, set the speed control, and pull the start cord. However I do not understand the wire that attaches to a tag at the bottom of the upper button. I do not see how you would use it to stop the engine, since it seems to be permanently grounded.
The magneto does not really look like an electronic type. My first guess would be that there is a wire on the other side of it that goes into the space inside the flywheel, and there are points and condenser located there. The kill wire, if it has one, would come out from either the magneto or the under side of the flywheel and go to a switch that grounds it.
Hi Grumpy thats the primer for the petrol for a cold start i dont know if its a flood button i usually push up and down a few times then pull the cord. in this picture you can see the bottom of the blue knob has a metal piece that touches the screw on the what i assumed was the kill wire. you are probably right about the wire going inside but as i said i cant see the end of it as it dissapears. what do you reckon about me taking off the flywheel and having a look ? any problems with me doing that ? you misunderstood me the contacts i meant were the ones that the side if the flywheel spin past i didnt open the magneto it is sealed. when i took off the cover to get to the pull cord/spring mechanism the spark plug cable fell out so i pushed it back in it has a tiny hole in the cable end and inside the magneto there is a tiny needle that pokes into the cable end to make contact. forgot to mention that yes the carbureter is attached to the primer
I took a couple more pictures for you one is of the magneto unscered you can see the wire disappearing under the flywheel. the other is of the carb so you can see the blue knob and what it does I have never had a look at the points(didnt know there were any)maybe they need replacing or the condenser or both (this i know from my older cars that had distrutors Pete
I did a bit of research last night on this particular machine, it appears it uses one of the early "lawn boy" motors as far as I can understand.
I would imagine with a old mower like that iot may not have a kill switch at all, like on the old victa 18's you just throttle it right back and it will stop.
To regain spark personally I would start by removing the flywheel and cleaning the points with either some very fine abrasive paper or a points file, just make surte you clean any dust out after you are done.
It looks to be a very simple ignition system with only 4 major parts, the coil, the magnet, the condenser and the points.
Pete, you have had the magneto coil mounted too close to the flywheel: it has scored the flywheel considerably. Use a visiting card and the slack in the coil's mounting holes to correct this. It won't fix your problem, but having the correct gap is part of the design parameters of the magneto.
The button with the long vertical travel goes into the center of the carburetor float bowl. There are two things it could do: it could push the float down, to flood the carburetor and enrich the mixture for cold starting, or it could push a needle into a fuel exit port to shut the fuel off completely, to stop the engine. So, is the button a priming device or an engine stop control? If it is a cold start aid, how do you stop the engine? If it is an engine stop control, how do you prime the engine?
To answer both of your queries to turn it off you just turn the blue knob clockwise about an inch or 2 and it turns off to turn on turn blue knob anti clockwise same amount. to start from cold you push the blue knob down onto second button whilst in the on position(wont work in off)to prime and then pull cord.
OK this is what i have done, i went outside and dug out my second iron horse from under the house both i got from my uncle and both exactly the same. This one is way worse than the one i'm working on, the Magneto has crumbled to bits. and is useless, I took off the flywheel and came to a brass colored cover with 3 screws and a tiny spring for the revs(it has 2 positions for revs ordinary or heavy depending on the state of your lawn)under the cover and my god in almost pristine condition are the points and condenser that would be the cleanest part of the whole mower, this is what i discovered, the wire from the magneto that disappers actually reappears under that cover and is attached to the condenser then another wire attached to the same bolt on the condenser goes to what i thought was the kill switch. Grumpy there is no way that i can see to adjust the gap on the magneto it only has 1 hole on each side to mount so i dont know how to fix the scoring problem. what should i do now ? you reckon i should pull the flywheel off my good mower and see what i find ??
That seems to be a very good manual, and the D400 carburetor certainly seems to be your carburetor. It does have a kill switch, and it works as you said. The button pushes for flooding (starting enrichment) and twists for kill. The breaker point gap should be 0.020", which is usual, and the gap between the flywheel and the coil core should be 0.010" rather than the generic 0.012" I quoted. There should be enough information on the table now so we can give specific answers to your questions, and so you can work through each procedure by following the manual.
Thanks Grumpy mate, did you get the manual and have a look or do you know the lawn boy motor ? you can kick me if you like but i undid the magneto/coil and this time pulled the screw completly out and now i see there is an oval shaped hole in the piece the screw goes through first which i couldnt see before because the screw head was covering it, so you are right there is room for a little bit of adjustment for the coil away from the flywheel. so hopefully no more scoring at least. going to pull the flywheel etc off and have a look. couldnt do it before my mother dropped in still driving at 80 years old not bad ahh
Magneto screws normally have a little slack in the mounting holes, and the amount of adjustment required is quite small. I thought you might just have rust and garbage in the holes preventing you from adjusting the clearance. The manual has detailed instructions for making the adjustment.
I was surprised both by the complexity of the engine and the detail in the manual. It appears to be an exceptional 2 stroke, but maintenance may be a problem without a supply of spare parts. You may also need to mount a small seat on the mower's push-handle to accommodate a riding mechanic.
Glad to hear your mother is still active - it may help keep her healthy. Hope she continues to drive safely, and enjoy it.
Hi Grumpy, I found that same site but on further looking i found this https://lookup3.toro.com/ttcGateway/acrobat/manuals/lball.html which is the same as the other site except you can download/save the individual section 1 by 1. My work table collapsed last night and sent screws etc everywhere lucky the mower got taken off by my daughter first so I'm fixing that today and waiting for her to come home from work to help me lift it back on the table (cause I'm in a wheelchair and cant get enough leverage to lift it). I tell you if its not one thing its another hahaha life's a challenge mate
I don't want to butt into your business, but depending on why you are in that wheelchair, it might be a really bad idea to be lifting anything much. I'll make an effort to keep from intruding, but please don't hurt yourself over a thing like this; life right now is a picnic compared with what it might be like if you cause yourself further damage. I suspect your daughter would agree with me.
Thanks for that URL - I've downloaded lots of stuff, and most of it is interesting.
Thanks for your concern mate and I don't think your butting in or intruding, I've always been pretty open to people, I find it takes down the barriers that able bodied people build up about Disabilities. I've been in this chair for nearly 30 years since i was 18,(Broke my neck in a diving accident) I think all the damage is done mate, And all the Paralysis is from my collar bone down so my arms are only affected slightly. I like to learn new things like this, all my mates talk about engines this and engines that and I just look at them blankly, so learning this is a start to put me on even grounds with them,Plus I want to really get this mower going I'll be rapt if i can. And my late wife would agree with you and my daughter, they always tell me "don't overdo it", but you know I've always been very independent which sometimes is a good thing,sometimes not Cheers and thanks for your help. I've been working trying to get the last screw on the cover of where the points etc are, it's always one screw or one bolt that wont undo. will keep you up to date on my progress. Pete
