Farm Boy Build-Wont Run!

[2kmoss]

All,
I have completed the build of Farm Boy #495. I spent all of last winter building it and had everything done except the ignition system and getting it to run. I have recently spent several evenings setting up the ignition and trying to get it to run and have had almost zero luck. I got it to sputter a couple of times early on but cant get it to hit a lick now.

The first problem is I am burning up Hall Effect switches like popcorn, they will work for a few hours of trying to get it to run and then zap! I'm sure its some kind of grounding problem sending high voltage thru the switch but am confused as to why as I have this ignition wired up per the provided directions.

When switches are functioning properly I get a nice blue spark that is very audible with the plug out of the hole and just grounded to the head. Once I re-install the plug I kind of hear the spark but it doesn't seem to be as "hot" as when the plug is removed??

I have all governer linkage removed and am just trying to get it to run first before I install and mess with the setup. I have the ignition set to fire right at about TDC. The exhaust opens a bit before BDC on power stroke and closes right at TDC of exhaust stroke. I seem to be getting good compression and the valves seem to be sealed real nice. I am using Coleman fuel and it seems to be flowing well into carb, maybe to well as I can flood it out real easy (fuel starts oozing past cylinder 0 ring if i choke it to much with the needle opened up a full turn).

Ignition Specs: (All ignition parts were purchased thru model-engine-ignition.com)
Battery - 6v using (4) AA Batteries
Ignition Module - PICTIM w/Buzz Coil Chip
Switch - Hall Effect Sensor w/Magnet on Cam Gear
Coil - Power Keg 4 Wire Coil
Spark Plug - Rimfire VR2L w/.020 Gap

Per the instructions the only thing I have grounded to the engine head is one of the secondary leads from the coil. The directions for the Ignition Module states to ground the module to the engine but in the information with the coil states that it is recommended not to ground the Ignition module if using a 4-wire coil. Sooo...

I will attempt to attach a few pictures of the current setup.

Thank you for any help or suggestions you may have!!

Kevin

 

[Cogsy]

I'm not familiar with that ignition so can't really help there - sorry. But while you're getting spark (assuming it's at the correct time), if you have good compression you should be able to get it to run.

It looks like you've done a good job on the build, and if you're able to flood the engine then I assume your intake valve spring is light enough to draw a fuel charge. My guess would be to start at the carb. Does the needle shut the fuel off completely? If it does, I would shut the needle entirely and put a couple of drops of fuel in the spark plug hole, then put the plug in and spin the engine over with an electric drill. If it starts to fire or even run for a few seconds then you've found your main issue. From there, you can crack the needle a tiny amount and spin it over, and keep trying slightly more needle opening until you find a sweet spot. Depending on your needle taper it could be extremely sensitive and may go from too lean to too rich in less than half a turn.

If it won't respond to the fuel down the plug hole at all, and still assuming your compression is acceptable, ignition timing would be the next thing I would look at. If you're hearing the spark with the plug installed then it should be fine. I'd be looking at timing. Some RC ignitions have built in automatic advance which can play havoc with getting timing correct.

Something in that lot may help, or at least narrow the search for the problem a bit. Let us know how you go.

 

[TonyM]

First of all Kevin thats a great looking engine and stand. I wonder if you are getting enough voltage to drive the ignition with 3 AA cells. The Tim is designed for 6V to 12V. 3X 1.5V aa cells would give a nominal 4.5V Try it with 4 or more cells. or better still a 6 Volt Lead acid. You could also reduce the plug gap a bit to .015 / .016. and see if that helps a low power spark

 

[Jasonb]

As Cogsy says a lot of these engines have a needle valve that is more like an on/off switch and you only need to open them up a crack for the engine to run with most needing only about 1/4 turn.

 

[Barnbikes]

I would ditch the Hall system and install a set of points. Cheaper to file points then buy new parts.

 

[2kmoss]

First of all Kevin thats a great looking engine and stand. I wonder if you are getting enough voltage to drive the ignition with 3 AA cells. The Tim is designed for 6V to 12V. 3X 1.5V aa cells would give a nominal 4.5V Try it with 4 or more cells. or better still a 6 Volt Lead acid. You could also reduce the plug gap a bit to .015 / .016. and see if that helps a low power spark

Tony,
My bad, I mis-typed. I have (4) AA batteries powering the ignition module, using a volt meter I get about 6.2 volts. The spark seems to be acceptable. Having the buzz chip in the module actually give me hundreds of sparks per second. When I purchased the ignition module everything I read said having the buzz type spark was better suited for these engines??

Thanks,
Kevin

 

[2kmoss]

I would ditch the Hall system and install a set of points. Cheaper to file points then buy new parts.

I would hate to have to ditch this system as it did cost a fair bit. Seems that many people have used them with success but at this point I am not one of them And I would have to find some room and a cam or something to actuate the points.

As you might tell I am a bit ignorant about these ignition systems.

Kevin

 

[2kmoss]

I'm not familiar with that ignition so can't really help there - sorry. But while you're getting spark (assuming it's at the correct time), if you have good compression you should be able to get it to run.

It looks like you've done a good job on the build, and if you're able to flood the engine then I assume your intake valve spring is light enough to draw a fuel charge. My guess would be to start at the carb. Does the needle shut the fuel off completely? If it does, I would shut the needle entirely and put a couple of drops of fuel in the spark plug hole, then put the plug in and spin the engine over with an electric drill. If it starts to fire or even run for a few seconds then you've found your main issue. From there, you can crack the needle a tiny amount and spin it over, and keep trying slightly more needle opening until you find a sweet spot. Depending on your needle taper it could be extremely sensitive and may go from too lean to too rich in less than half a turn.

If it won't respond to the fuel down the plug hole at all, and still assuming your compression is acceptable, ignition timing would be the next thing I would look at. If you're hearing the spark with the plug installed then it should be fine. I'd be looking at timing. Some RC ignitions have built in automatic advance which can play havoc with getting timing correct.

Something in that lot may help, or at least narrow the search for the problem a bit. Let us know how you go.

Cogsy,
Yes the needle valve is very sensitive, very easy to flood the engine out. I am thinking that is part of my problem, to much fuel at times shorts out the plug? I think?

Intake Valve spring is another thing I have messed with quite a bit. When you spin the flywheel with your finger choking the carb I can see the intake opening maybe .02-.03 (just a guess but it is moving pretty good). Now when I spin the flywheel with no choke the intake still cycles but it is barely perceptable, again maybe .005-.010 movement. Does this sound about right?

I need to solder in another Hall switch before I can try to start it again, then I can try adding some fuel manually as you suggest. What would ether do?? I figured that might be way to much boom for this thing so havent tried that Also want to figure out why I am burning up these switches before I try to much more as I have burned out 3 so far and only have 2 left. Plus its a pain to un- solder an re-solder a new one in after you have done it a few times.

Thank You!

 

[Engine maker]

Cogsy,
Yes the needle valve is very sensitive, very easy to flood the engine out. I am thinking that is part of my problem, to much fuel at times shorts out the plug? I think?

Intake Valve spring is another thing I have messed with quite a bit. When you spin the flywheel with your finger choking the carb I can see the intake opening maybe .02-.03 (just a guess but it is moving pretty good). Now when I spin the flywheel with no choke the intake still cycles but it is barely perceptable, again maybe .005-.010 movement. Does this sound about right?

I need to solder in another Hall switch before I can try to start it again, then I can try adding some fuel manually as you suggest. What would ether do?? I figured that might be way to much boom for this thing so haven't tried that Also want to figure out why I am burning up these switches before I try to much more as I have burned out 3 so far and only have 2 left. Plus its a pain to un- solder an re-solder a new one in after you have done it a few times.

Thank You!

I made #003 and have helped with several others.

First don't change to a set of points, the hall effect is far superior!

Your using a buzz coil set up. Remember that a Buzz coil fires when the magnet is over the sensor. and a single spark fires as the magnet leaves the sensor. The Farmboy was designed as a single spark, so using a buzz coil will change the timing. All my engines except 2 run single spark and those 2 only have a buzz coil because of the contact (wiper) setup.

If you spin your engine over on a compression stroke does it bounce back a few times? I've seen this engine seem to have good compression but not run. But if you change the "O" ring it takes right off. Never have figured that one out!

As for the hall effect burning out the major cause of this is a bad ground. I always ground to 2-3 different places just to make sure of the ground.

If you think it's flooding. I have a short piece of pipe with a 1/4 - 32 thread with a plastic tube attached. I put it into the plug hole turn the piston to TDC, hold the exhaust valve open, and blow the excess raw fuel out of the cylinder. Only open the needle valve 1/8 to 1/4 turn to start.

Are you coming to "Cabin Fever Expo" by chance.

You can send me a private message and I'll tell you how to get in touch if you want to talk try other Ideas.

Jim G

 

[2kmoss]

I made #003 and have helped with several others.

First don't change to a set of points, the hall effect is far superior!

That was my impression as well.

Your using a buzz coil set up. Remember that a Buzz coil fires when the magnet is over the sensor. and a single spark fires as the magnet leaves the sensor. The Farmboy was designed as a single spark, so using a buzz coil will change the timing. All my engines except 2 run single spark and those 2 only have a buzz coil because of the contact (wiper) setup.

If you spin your engine over on a compression stroke does it bounce back a few times? I've seen this engine seem to have good compression but not run. But if you change the "O" ring it takes right off. Never have figured that one out!

Yes, it seems to have very good compression and will give a nice bounce.

As for the hall effect burning out the major cause of this is a bad ground. I always ground to 2-3 different places just to make sure of the ground.

Yes I discovered this last night. I wired up a new Hall Effect switch and was adjusting the timing and had the plug removed and also was checking the spark. The spark just wasnt very good but I heard a good buzz but it wasnt coming from the spark plug! It was arcing from the hall switch leads back to the frame! So I put some electrical tape around the switch leads for insalation. Well it then stated arcing from the face of the switch and jumping over to the cam gear! So I then placed tape over the face of the switch and that seemed to stop it. But I obviously need some better grounding. And once I got the arcing stopped the spark at the plug seemed much better.

If you think it's flooding. I have a short piece of pipe with a 1/4 - 32 thread with a plastic tube attached. I put it into the plug hole turn the piston to TDC, hold the exhaust valve open, and blow the excess raw fuel out of the cylinder. Only open the needle valve 1/8 to 1/4 turn to start.

Are you coming to "Cabin Fever Expo" by chance.

Too far from me but it looks pretty interesting.

You can send me a private message and I'll tell you how to get in touch if you want to talk try other Ideas.

Jim G

Thank you for the offer, I may need to take you up on that before this is over

Now for the good news! The engine sputtered to life and ran for about 3 minutes! I played with the mixture and it seemed to need at least half a turn open to stay running but I think it was still a bit rich. I didnt have any water in the hopper and it got warm but not really hot. It started sounding like it was knocking or something (the sound change was obvious) and then it died. I then added some water and let it cool down and then tried in vein for another 30 minutes or so to get it to run again with no luck. One thing I need to check is to make sure the timing gear didnt slip out of position while it was running, that could be why it started knocking. I gave up for the night and will mess with it some more this weekend if I get the chance.

Thanks for your Help!
Kevin

 

[gbritnell]

I downloaded the PDF installation information for the coil and in the text it says that the primary and secondary grounds should not be hooked together but if you look at the schematic it shows that both of them go back to ground. ???? A coil winding has to have a power supply and a ground. When you apply power it creates an electromagnet. Now you take that winding and wrap it around another winding of many more turns and you have a coil. When the magnetic field collapses from the first winding the collapsing field is transferred to the secondary winding and because of the extra windings you get a higher voltage which will create a spark. Now for the current to flow in the secondary winding it needs a path, from the spark plug to ground. So now you have a common between the primary winding and the secondary winding and that's the ground. There is only one ground, the negative path back to the battery so I don't understand why the text says to NOT hook them together when the schematic shows them both going back to ground. If you are continually burning Hall transistors then you don't have good ground path. If it were me I would make sure I had good grounds from the coil and ignition through the engine and that should eliminate the Halls burning out.
I would set my timing to about 5 degrees advanced to start off with. Clean the plug, close the needle valve, spin the engine over and while spinning it over slowly open the needle valve. When it gets to the point where there is a good air/fuel mixture the engine should start to run on it's own, then it's just a matter of fine tuning the needle. As the engine gets hot it generally requires a little richening of the needle valve because the engine starts to run lean. If you're engine ran, got hot and then wouldn't restart it's probably because the heat soaked into the carb and boiled the gas out (vapor lock). Most hit and miss engines don't get that hot but if and when you get the engine running again after it has run for a short time shut it off and let it sit for a minute. Now feel the carb. If it's hot then that's what's happening. The only way to fix that is to make an insulator to go somewhere between the carb and head.
gbritnell

 

[2kmoss]

I downloaded the PDF installation information for the coil and in the text it says that the primary and secondary grounds should not be hooked together but if you look at the schematic it shows that both of them go back to ground. ???? A coil winding has to have a power supply and a ground. When you apply power it creates an electromagnet. Now you take that winding and wrap it around another winding of many more turns and you have a coil. When the magnetic field collapses from the first winding the collapsing field is transferred to the secondary winding and because of the extra windings you get a higher voltage which will create a spark. Now for the current to flow in the secondary winding it needs a path, from the spark plug to ground. So now you have a common between the primary winding and the secondary winding and that's the ground. There is only one ground, the negative path back to the battery so I don't understand why the text says to NOT hook them together when the schematic shows them both going back to ground. If you are continually burning Hall transistors then you don't have good ground path. If it were me I would make sure I had good grounds from the coil and ignition through the engine and that should eliminate the Halls burning out.
I would set my timing to about 5 degrees advanced to start off with. Clean the plug, close the needle valve, spin the engine over and while spinning it over slowly open the needle valve. When it gets to the point where there is a good air/fuel mixture the engine should start to run on it's own, then it's just a matter of fine tuning the needle. As the engine gets hot it generally requires a little richening of the needle valve because the engine starts to run lean. If you're engine ran, got hot and then wouldn't restart it's probably because the heat soaked into the carb and boiled the gas out (vapor lock). Most hit and miss engines don't get that hot but if and when you get the engine running again after it has run for a short time shut it off and let it sit for a minute. Now feel the carb. If it's hot then that's what's happening. The only way to fix that is to make an insulator to go somewhere between the carb and head.
gbritnell

Yes, the instructions for wiring that ignition module and coil are full of confusion! The gentleman that sells these seems very nice and is always there to answer questions, the problem is I dont get the feeling he knows much about them. I email and asked about wiring this stuff up and he indicated that I had it properly wired and it should work fine. He recommended that I go ahead and ground the ignition module to the engine frame as well, when I did that I got NO spark...nothing. Sooo......thats how I ended up wiring it and adding the extra insulation around the hall switch after I noticed that problem. I certainly need to add more gounding of some kind but a bit unsure of where to go.

I will fool around a bit more with the mixture, timing, etc. this weekend.

Thanks!

 

[gbritnell]

All of my engines use Hall triggers down to the smallest hit and miss engines. I use a single fire S&S ignition module and a Jerry Howell TM-6, both work well. I have a wires from my ignition box, one ground to the frame of the engine, one HT lead to the spark plug and a twisted 3 wire set going to my Hall transistor. I have the magnet mounted in an aluminum disc on the crankshaft which gives a spark every revolution.

 

[johnstij]

For my Farm Boy engine #558 I built a Jan Ridder vapor carburetor which is connected directly to the inlet port the engine just sucks the fuel/air vapor into the cylinder. If you email Jan he will send the plans.
http://ridders.nu/Webpaginas/pagina_benzinedamp_carburateur/dampcarburateur_frameset.htm

Ian

 

[2kmoss]

All of my engines use Hall triggers down to the smallest hit and miss engines. I use a single fire S&S ignition module and a Jerry Howell TM-6, both work well. I have a wires from my ignition box, one ground to the frame of the engine, one HT lead to the spark plug and a twisted 3 wire set going to my Hall transistor. I have the magnet mounted in an aluminum disc on the crankshaft which gives a spark every revolution.

That's a beauty! Looks and sounds great!

 

[2kmoss]

Ok I got it running and it ran fast! Had to install governor to slow it down Found a couple problems that I got fixed up and it made the difference between sputtering and running

First was something Jim said about installing a new o-ring. Compression felt good but o-ring had been in engine for awhile and after putting a new one in it REALLY had good compression! Second was the fuel feed. I installed a check valve into the fuel tank which was just a 1/16 ball bearing that was held in a drilled hole by gravity. Apparently I needed so much vacuum to lift it off of its seat that i had to open needle alot to get fuel to flow through it which caused flooding. So with that removed fuel is flowing like it should. I will upload a video of it running.

It obviously still needs some adjustments to smooth it out and slow it down but I'm pretty happy to get to this point. Thanks for all the help!!

 

[2kmoss]

Here is the video:


Any advice on getting it smoother and slower running?

I also notice that when I touch engine while it's running I can feel a slight shock! Better ground needed I assume?

 

[Mago]

I finished the Farm Boy a little while ago and had some starting problems.
Various contributors have made very valid suggestions so I don't want to repeat it all again.
However I don't think anyone has suggested that you make the governor inoperative.
If you are trying to start the engine with a drill the starting speed is fast enough to operate the governor which will open the exhaust valve and not allow the engine to start.
To isolate the governor put a couple of elastic bands around the governor balls where the spring is and try starting.
Good luck.

 

[Engine maker]

Glad to hear you got it running. Way to go

You need a much lighter spring between the governor weights. You should see them get thrown out every time it fires. You can also wind in the screw on the governor latch that pushes the latch away from the valve slider. That adjustment will change it about 50 rpm.

As for the "O" ring I've seen that happen before on other engines. Engines that have run for years on the same "O" ring all of a sudden won't run with what seems like good compression. I've seen a couple that were just shut down and would not restart. Go figure! But at least the ring job is quick and cost less than a dollar!

On mine I installed the check valve in the fuel tank. I used an aluminum RC fuel filter. I unscrewed the filter and just dropped a small ball bearing in the filter. As long as the filter is vertical no spring is needed. FYI you have to use the aluminum filter because it unscrews, the plastic ones are glued together. If you look back in this forum somewhere you can see my tank with the purple fuel filter in the tank. With the better compression from the new "O" ring it would probably have opened the check valve.

I was hoping you were going to Cabin Fever Expo so I could have a good look at your engine. You must have seen mine somewhere and liked it because the tank and sled look just like mine! Thanks

Jim G

 

[2kmoss]

Glad to hear you got it running. Way to go

You need a much lighter spring between the governor weights. You should see them get thrown out every time it fires. You can also wind in the screw on the governor latch that pushes the latch away from the valve slider. That adjustment will change it about 50 rpm.

As for the "O" ring I've seen that happen before on other engines. Engines that have run for years on the same "O" ring all of a sudden won't run with what seems like good compression. I've seen a couple that were just shut down and would not restart. Go figure! But at least the ring job is quick and cost less than a dollar!

On mine I installed the check valve in the fuel tank. I used an aluminum RC fuel filter. I unscrewed the filter and just dropped a small ball bearing in the filter. As long as the filter is vertical no spring is needed. FYI you have to use the aluminum filter because it unscrews, the plastic ones are glued together. If you look back in this forum somewhere you can see my tank with the purple fuel filter in the tank. With the better compression from the new "O" ring it would probably have opened the check valve.

I was hoping you were going to Cabin Fever Expo so I could have a good look at your engine. You must have seen mine somewhere and liked it because the tank and sled look just like mine! Thanks

Jim G

I have been playing with the governor spring and have got it slowed down a bit. It still needs a bit more tweaking bit I am happy with it! Now I'm gonna tear it down and paint, polish and bling it up a bit.

Yup I scoured this site for ideas for the sled and fuel tank and yes I used your ideas for both the sled and the clear ends on the tank! Yours was my favorite by far! Even purchased the watch crystals for the ends

I hope your flattered by my copying your brilliant ideas! Lol

I'll post up the final product when I'm finished. Now I need some of those stickers on the side or yours;-) I cant pin stripe either lol

Thank you for all your help!

Kevin