Help Please. Troubleshooting a New Webster

[Minibrix]

You said :
"the plug sparked when expected, although that plug spark looked puny to me."
From my experience with old motorbikes, it sounds to me like the spark is failing under compression, you should get quite a long spark from the HT lead without the spark plug, at least 1/4 inch, (take care it bites) if not it could be the coil. It looks like your using an old coil, the insulation may be cracked or breaking down internally, if you can test when dark you can sometimes see the it sparking across the insulation on the coil.

 

[Cogsy]

It is certainly possible that your spark is failing under compression but I would try the fuel test first as it's simple to perform. I would dispute the statement " if you have any evidence of fuel in the combustion chamber then it can only be ignition" as a properly flooded engine will absolutely refuse to fire at all until most of the excess fuel is removed and the plug dried out. If your carb settings are way off it will continually be drawing more fuel into a flooded condition and it will never fire. Just a note - the carb you are using is likely a methanol carb and is probably set far too rich from factory to run on gasoline/coleman fuel. Disconnect the fuel entirely, dry the plug out, squirt a few drops of fuel in the plug hole and see what happens. If it doesn't fire then, then chase ignition issues.

 

[Brian Rupnow]

If you are still uncertain about your valves or ring holding compression, build an adapter like the one in the picture, (tailor the thread to match whatever sparkplug you use) screw it into the sparkplug hole, hook an airline to it and put on about 20 pounds of air pressure. Make sure that the piston is at top dead center, hang on tight to the flywheel because it will try to rotate to bottom dead center and take any unwary fingers with it on the way. This will immediately show the location of leaks---air coming out of carburetor, air coming out of exhaust, or air coming out around piston.
This is a diagnostic tool I use. The metal piece of sparkplug can be whatever fits your particular engine.

 

[young1]

In your original post you state you are getting spark when points close and when they open. You should only be getting a spark when the points open. May also have fuel issues but I would check out why you are getting two sparks. DAve

 

[XD351]

I will go out on a limb here and say it could be your ignition set up , it looks like the cam is just a metal ring with a flat machined on it so the points would be held open most of the time and only closing briefly then opening again . Usually the opposite is the case as this allows current to flow through the coil to build up the magnetic field in the coils , when the points open the current stops and the magnetic field breaks down creating an emf in the secondary coil . The condensor stops arcing across the points but also causes a ringing effect as its charge tends to ebb and flow back into the primary winding which helps to produce a better spark .
If your points are always open the condensor is charged and just dumps its stored electrons to ground when the points close effectively making it useless . Your problem could be that having the current flowing through the coil for such a short time isn’t allowing the coils to fully saturate and produce the maximum magnetic field and thus a weak spark which will get weaker the faster you spin the motor . That is the reason points type ignition have a setting called dwell angle which is set by the points cam profile and points gap . I have had full sized engines that run like a dog if the points gap is too far out of whack and i once had a Yamaha bike that wouldn’t start if the gap was 0.005 inch out .
With the carby you may find coleman fuel ( shellite or lighter fluid ) is thinner than nitro fuel used in model cars or planes as they also have oil in the fuel so you may need to close up the idle and high speed needles a fair bit , i would close them fully then clean the engine out and dry the plug off ( heat it with a lighter ) then try some ether starter spray like aerostart or similar and see if it kicks and if it doesn’t you have at least ruled out a fuel issue .
The car coil should give you a nice hot blue spark that will jump a 1/4 inch gap easily even if you are just flicking the motor over by hand .

 

[Brian Rupnow]

The ignition cam on all of my engines are round with a flat on one side, and they all work perfectly. And yes, there will be two points at which the plug will spark--that's normal.

 

[bill70j]

Thanks Guys!

I very much appreciate all of your input.

I need to study all of your new posts and develop an ordered list of things to do.

Got time today, so hope to report back with good news.

Thanks again,

Bill

 

[werowance]

on the note of points for this engine. what would be the recommended gap setting for points on this engine?

 

[bobden72]

"Cogsy, post: 321249, member: 12083"]It is certainly possible that your spark is failing under compression but I would try the fuel test first as it's simple to perform. I would dispute the statement " if you have any evidence of fuel in the combustion chamber then it can only be ignition" as a properly flooded engine will absolutely refuse to fire at all until most of the excess fuel is removed and the plug dried out. If your carb settings are way off it will continually be drawing more fuel into a flooded condition and it will never fire. Just a note - the carb you are using is likely a methanol carb and is probably set far too rich from factory to run on gasoline/coleman fuel. Disconnect the fuel entirely, dry the plug out, squirt a few drops of fuel in the plug hole and see what happens. If it doesn't fire then, then chase ignition issues.[/QUOTE]



I agree it sounds like a ignition problem, if the spark plug is coming out damp then no ignition is taking place. I would suggest a weak spark, it my look good outside the cylinder but when under compression is a different matter. You are looking for a fat dark blue spark outside not a wishy washy pale blue.

 

[ranger]

hi gents
My first time posting anything on here, just joined, Question, does this engine have a full size spark plug or a "model size" one? the ignition coil, is it a "full" 12volt unit or one which needs a ballast resistor? My reasons for asking are, a miniature type spark plug can be "overwhelmed" by the voltage from a full size car type coil, also running a ballast resisted coil without a b/r would be like running a 12volt system on 18-24volts!
this could cause the spark to track across the plug insulator when installed. you could also have a faulty condensor (even if it's a new one). something else to check. Doug.

 

[Brian Rupnow]

It has a small "automotive size" sparkplug 10mm diameter, but they perform just fine with a 12 volt coil and a condenser on the ignition points.

 

[bill70j]

Thanks again for everyone's inputs! I am first going to look at possible ignition problems. And if I can't find anything there, I am going to build Brian's engine starter system for the drill and also his compression tester. Then I can try all of the suggestions you all have given me on compression and on the fuel system.

Hi Johwen here. Check the colour of the spark, Is it a blue spark or yellow? It should be blue. It would appear to me you should be getting pops and bangs if you have ignition even if if won't continue to run because of timing, even gasket leaks and carburation. If you have any evidence of fuel in the combustion chamber then it can only be ignition. These are my thoughts. John

Thanks, John. I pulled the spark plug, turned off the lights, and looked at the spark. It was white-blue, much like an oxy-acetylene oxidizing flame. It definitely wasn't yellow. And while it was a small spark, it was quite bright.

You said :
"the plug sparked when expected, although that plug spark looked puny to me."
From my experience with old motorbikes, it sounds to me like the spark is failing under compression, you should get quite a long spark from the HT lead without the spark plug, at least 1/4 inch, (take care it bites) if not it could be the coil. It looks like your using an old coil, the insulation may be cracked or breaking down internally, if you can test when dark you can sometimes see the it sparking across the insulation on the coil.

Thanks Minibrix. I disconnected the HT lead from the spark plug and put it across from ground. It started arching once it was within 5/8" of ground. A loud, orange-yellow spark that did look menacing. As far as the coil goes, the one in the photo is left over from a tune-up years ago. I bench tested the primary and secondary coil resistances and both checked OK. But I switched that old coil out with a new one anyway and see no noticeable difference.

I agree it sounds like a ignition problem, if the spark plug is coming out damp then no ignition is taking place. I would suggest a weak spark, it my look good outside the cylinder but when under compression is a different matter. You are looking for a fat dark blue spark outside not a wishy washy pale blue.

bobden72: Thanks . I just checked the spark again outside the cylinder. It's bright, but whitish-blue. Definitely not dark blue. Thoughts?

The car coil should give you a nice hot blue spark that will jump a 1/4 inch gap easily even if you are just flicking the motor over by hand .

Thanks, XD351: I just laid the HT lead 1/4" from ground and turned the engine over by hand. The spark that jumped the gap is orange-yellow, not hot blue. Since I had already changed out the coil, I went ahead and switched to a different condenser. That spark is still definitely orange-yellow. I am fairly certain my ignition set-up is the same as others who have been successful starting their Websters. So maybe I am missing something glaring. Thoughts?

hi gents
My first time posting anything on here, just joined, Question, does this engine have a full size spark plug or a "model size" one? the ignition coil, is it a "full" 12volt unit or one which needs a ballast resistor? My reasons for asking are, a miniature type spark plug can be "overwhelmed" by the voltage from a full size car type coil, also running a ballast resisted coil without a b/r would be like running a 12volt system on 18-24volts!
this could cause the spark to track across the plug insulator when installed. you could also have a faulty condensor (even if it's a new one). something else to check. Doug.

Thanks for your thoughts, Doug. Several others have built the same engine with the same ignition ignition design as mine, and their engines run fine. I think I am missing something fundamental. Would appreciate any further input.

 

[oldengineguy]

For what it's worth, I have built several single cyl hit &miss engines and find that they either wont start or wont run well on camp stove fuel. Try using regular 87 octane and put up with the smell, it is quite a bit stinkyer.

 

[pjoe]

try a different sparkplug.

 

[bobden72]

For what it's worth, I have built several single cyl hit &miss engines and find that they either wont start or wont run well on camp stove fuel. Try using regular 87 octane and put up with the smell, it is quite a bit stinkyer.

Yep I am with you there try some real fuel, and maybe close the plug gap to see if you get a darker blue spark.

 

[bill70j]

Thanks to all who have helped me troubleshoot the Webster. It now runs!

I did a lot of the things that were suggested, but can't point to a single one that made the difference. I did replace all the gaskets and smeared them with grease before installing them. I also replaced the ignition coil and condenser and re-set the timing to TDC.

I decided to build and install Brian's starter system that helped speed up fine-tuning the carburetor. The original factory settings were way too rich, as you all suggested.

I leaned a lot with this exercise, which will be invaluable on future builds. So Thanks again!

Bill

 

[minh-thanh]

Congratulations !!
Nice engine.

 

[Brian Rupnow]

Bill---I'm so happy for you and your Webster. It is a great little engine to learn on. Congratulations on your success.---Brian

 

[aka9950202]

Well done . Good to see another running webster.

Cheers,
Andrew in Melbourne