Two Timer Build

[rwm]

Those look nicely proportioned for this engine.

 

[Chris Hamel]

Really looking good. I think drawings are overrated.

 

[rdean]

Thank you Robert and Chris I think they will be OK for this engine. I am trying to make a slow running work horse not a speed demon.

I turned, threaded, and drilled two pieces of brass rod for the intake ports. Note the o-rings that will seal inside the intake manifold.


Intake manifold is made from 1/4" sweat copper fittings soldered together and painted.
They slide up over the brass rods and the o-rings seal them.


The copper fitting is just the right size to be threaded 7/16 fine for the carburetor to screw into.


The carburetor is one I had tried on another model and it did not perform well but I will give it one more try on this engine.

Now that I have the intake manifold sorted out I have a better sense of how the engine will sit. It is way too high so I cut 1" off the box I had made to lower it.



I have a nice piece of maple that I will be using for the base and probably add some rubber feet as well.

Thanks for looking
Ray

 

[rdean]

Sanded and shaped the base plate with a cutout for the upper box. Several coats of clear spray enamel and time to dry.


Jump forward to the base and box assembled with rubber feet. While I had it upside down I installed the On/Off switch, the battery holder, and the ignition module.


I milled some slots for the spark plug cables and the hall sensor wire so they would exit the box just above the base plate.
This is much neater than just cutting a large hole in the side of the box.


And the view from the other side.


I added some clear vinyl tubing to the intake manifold. On another engine, with the same design for the intake manifold, I found that even though there were o-rings on the intake nipples there was a vacuum leak. It caused all kinds of problems until I figured it out and may be why this carburetor didn't work well before on that engine.

The tubing is a very tight fit over the copper fittings and the spring clamps squeeze the tubing down on to the nipples.
This also increases the rigidity of the manifold.

Thanks for looking
Ray

 

[rwm]

I find that vinyl tubing gets very soft at temp. If you run the water cooling that may not be an issue. I'll bet you could machine a cool intake manifold that bolts on there. Maybe something V shaped? Would there be value in tuning the runner length?
Robert
Edit:
"I am trying to make a slow running work horse not a speed demon"
I suppose not then!
Robert

 

[Steve-F]

You really should try to organize your shelves better, how can you possibly find anything!! Great job so far! Just Awesome

 

[mattthemuppet2]

View attachment 385415

Thanks for looking
Ray

that looks just fabulous and very ingeniuous use of the taper bushings!

 

[rdean]

Thank you Steve, Matt and Robert.

I used this same arrangement with the tubing on my 90 Degree Twin and it has worked fine there. I will keep an eye on it for now but a cast manifold is above my pay scale.

Today started out just fine but then disaster. I made a 2" diameter pulley with two magnets to fit on the crankshaft to fire the hall sensor and run the water pump.
I also mounted the hall sensor.



After I installed the pulley I was checking for spark that should be every 180 degrees of crank rotation. They only fired every 360 degrees not good. I was very careful to get the magnets glued in to the pulley the correct way around and I verified that indeed I had done them correctly.
Then It struck me when I built my first twin over a year ago I had the same problem. The magnets were too close together and they interfered with each other. I corrected the problem on that engine by making the magnet wheel 2.25 in diameter and placing the magnets as far out as possible. I knew better but just didn't think when I made this wheel.
I started over with a 2.5 diameter slug and placed the magnets to the outer edge just to be safe. Now the plugs were firing every 180 degrees of crank rotation but the wheel was a little too tight on the crank and would be hard to adjust. Turning this wheel sets the ignition timing for both cylinders and should be easy to move. No problem got the 0.501 reamer out and went to work on the bore of the wheel under power. Yep the reamer caught in the bore and now it is way crooked.
That is where I stopped for today.
I don't need any more oops.
I will make a bushing that I can press in to the pulley and than ream it to size being more careful this time.

Thanks for looking

Ray

 

[rwm]

Interesting about the Hall sensor. Would weaker magnets eliminate the interference?

 

[rdean]

Robert I did look for some 1/4" ceramic magnets to try but I couldn't find any around here but I think they would have worked fine.

Short day in the shop but I did get the magnet pulley sorted out.
I bored out the pulley to 5/8" and made a 1/2" to 5/8" steel bushing and pressed it in the pulley.
Runs true now.



Thanks for looking
Ray