Building a Bonzer Bonzer

[Philjoe5]

I don't like the look of the backyard

I should box it up and send you a bunch Jim.

Thanks Barry. Once I get this engine running on its carburetor I want to go back and experiment with the Ridders.

While waiting for Monday, I decided to make some better keys for the flywheels. I once had a nasty experience with a set screw missing the key and jamming itself in the keyway of the shaft. I had to make a pulley puller to remove the wheel. So in all of this trial assembly work I used brass keys for easier removal.

I saw keys of this sort on my friends Fairbanks Morse last weekend and I liked the design for 2 reasons.



One, you've got a nice tab to grab for removing it from the keyway. And two, you can cut them to a length such that you're guaranteed they will sit under the set screw. Now they can't slide out the other side and be snatched away by those pesky shop gremlins



Cheers,
Phil

 

[Philjoe5]

I mounted the engine and fuel tank on a base that made it seem like I knew I had a runner. Went to the cycle shop and talked to the guy about his vintage Atlas lathe and its rocker style tool post. The lathe is in need of a better 3 jaw so I'll help the guy find one.

We also talked about an ignition system (my primary mission) and we decided on a 12V system. Parts were ordered and should be here in a few days.

Here's the engine all bolted down with the fuel tank now leak tested and fuel line clamped in place. I still have good compression which means I have, for now, driven out the demon who kept introducing a leak in the cylinder.



Thanks for looking. A video is Imminent

Cheers,
Phil

 

[Brian Rupnow]

Phil--Put the water jacket on and fill it with water before you start it the first time. Trust me--Once it starts, you aren't going to want to shut it off for a while.

 

[Philjoe5]

Brian,
I decided to take your advice on the water jacket. I've waited this long, another week won't make much difference,

Cheers,
Phil

 

[Philjoe5]

Now just waiting for ignition



Cheers,
Phil

 

[Brian Rupnow]

Loverly!!!

 

[Philjoe5]

I have a good ignition system now and get a spark I can hear when the plug is outside the engine. I have Brian's carby attached and could get a few short runs but not enough to keep it going. I had the sweet aroma of exhaust fumes which I think acts as a stimulant

. Without water in the jacket the engine actually got hot, but not so much I couldn't touch the head with a bare hand.

I've tried adjusting valve timing, ignition timing and carburetor settings but no joy yet. I also tried adjusting the intake valve spring tension.

I'm taking the rest of the day off while I ponder my next move.

Compression is still good so I'm optimistic.

Cheers,
Phil

 

[AussieJimG]

Yipee! It lives!!!

Jim

 

[cheepo45]

Glad to see you got it running! Now it's just fine tuning.
cheepo45

 

[Philjoe5]

Glad to see you got it running!

Thanks cheepo45 but I'm not doing the happy dance yet. I have noticed that if I get the engine firing enough to get things hot, the whole works seem to get much stiffer. I'm going to investigate this because I did machine the aluminum piston to be a fairly close fit in the bore. I don't want to believe the fit is that close, but it's just another factor I need to eliminate.

Cheers,
Phil

 

[Philjoe5]

I had a pretty good day today, but no happy dance just yet. With this setup



using the Ridder's vapor carb I was able to get a sustained run of probably 15 seconds before the engine coasted to a stop. During that time I was trying to decide whether to reach for the air inlet valve (I was on full choke) or the camera. Then runs got progressively shorter, and finally no pops. The spark plug was dry and except for a little soot looked OK. Consultation with AussieJimG leads us to believe that perhaps the fuel was getting colder due to evaporation and I wasn't getting enough fuel to the engine when I decided to quit. That should be easy to prove when I try running tomorrow. If I get the same result, I'll switch to Brian's carby and see what happens.

I would guess that with all the attempts I had a full 3+ minues of run time and I can't believe how much the compression has improved.

After the 15 sec run I called my wife to the basement shop to be a witness, but at this time she's unwilling to testify in court

I'm really encouraged by today's results. I currently have the battery on the charger. I want all the spark I can get tomorrow.

Cheers,
Phil

 

[Brian Rupnow]

Phil--It sounds like you are almost there. Best of luck, and I'll cross my fingers for you.---Brian

 

[Philjoe5]

Thanks Brian. I'm tantalizingly close. If it doesn't run tomorrow, I'll plumb in your carb and try it. Everything everyone said about increasing compression after just a short run-in is absolutely true. It's an impressive thing.

Cheers,
Phil

 

[Generatorgus]

We're rootin' fer ya!! Your persistence will prevail.

 

[X3MyWill]

I built one of these engines a few years ago. The symptoms you describe (runs for a short while then coasts to a stop) sound a bit like the problem I had. I traced the problem to the spark flashing over from the plug connection to the head. I was using a 12 volt car coil and battery and the spark voltage was sufficient to track down the insulator of the plug no matter how clean it was or how I positioned the connector. It seem to only happen when the engine started to warm up. The tracking may not be that obvious in a well light workshop. You say that your ignition system gives a very strong spark so I would check for this problem. My bonza has a very simple vapour fuel system consisting of a glass jar with connected to a brass intake tube with a 4.5mm hole by a 5 mm tube. I have been amazed at how such a simple system can work so well. I have never had any trouble with this system.

 

[Philjoe5]

Thanks for the tip X3. I have a worklight over the engine that I can switch off to see if I'm having the arcing problem.

BTW, my shop is about 62 - 64F these days. I'm wondering if the vapor carbs work more efficiently at higher temps?

Cheers,
Phil

 

[Brian Rupnow]

This is the part where I go absolutely crazy. Everything seems to be right, but the friggin' thing won't keep running. This is where you go back over everything and take a second look. First, check the valve timing. Then check the ignition timing--and then, what the heck d you check??? The carb works--I know that because it worked on my engine. Your flywheels are heavy enough, because other people built the engine with the same flywheels, and their engines ran okay. You say that your compression is good and better. Good luck!!!

 

[Philjoe5]

Here's an update. I still have very good compression but did not get a single pop today. Spark is good even though the battery is reading 6 V instead of 12 V. Could be my Harbor Freight meter but that's going to be checked out.

And an observation that makes absolutely no sense. With the Ridder's carb hooked up I was getting fuel pushed out of the vent hole on the compression stroke. That suggests an intake valve not seating, but then why do I have compression

I switched to Brian's carb and not a pop either. Also, after much cranking, when I removed the fuel line from the tank, it was dry and should have had fuel in it.

Then, all of a sudden the engine got very tight. By successively loosening components I traced this to a binding cam gear, so that needs attention.

I decided to strip the engine down and test all the component assemblies thoroughly. With the crankshaft and cam driving gear out of the picture, the piston moves nicely in the cylinder and it's hard to push it to TDC.

This is going to take a while. I'll be back

Cheers,
Phil

 

[Lawijt]

Hi Phil,

Is the timing for the ignition still correct? Maybe the timing is too late now & when the engine suck fuell & air , the spark arrive, all blow out??

Barry

 

[Philjoe5]

Hi Barry,
Yep, spark is about 10 degrees before TDC. I tried going to more retarded, then more advanced with nary a pop.

Cheers,
Phil