Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Ok, I’ve reassembled an engine or two without the benefit of timing marks, so here goes.

First, this one is easy because we essentially have all we need to see from the outside whether it’s correct or not.

Assuming it’s assembled now, everything moves as it should, do exactly this.

Unplug the spark plug wire, and remove the spark plug.

Insert a small diameter PLASTIC probe, (nothing that will scratch, or leave splinters behind), maybe a coffee stirrer or similar, into the spark plug hole, to use as a feeler gauge to feel the piston reaching  top dead center. It’s gonna be inserted at an angle, so be careful not to pinch the probe when the piston comes up.  You’re gonna want to turn the engine very slowly, by the flywheel, while feeling with the probe. There will be a small, indistinct, dead band in the middle of tdc, as the rod reaches tdc and swings through, so you’ll need to play with that until you have a good feel For TDC.
You want to be on the firing stroke, so turn the flywheel correctly, counter clockwise like it’s running, and watch the valve lifters. once the exhaust valve lifter cycles, then the intake opens and closes, the very next thing is the power stroke. This is where you insert the plastic probe, and feel for tdc. As you approach tdc, watch the ignition points and the cam.  If the arm is straight up, the points assembly level, then the piston ought to come to tdc just about exactly when the points close (calling for spark). Alternately, you can put the spark plug wire on the loose plug you removed, turn the battery on, and observe spark while feeling for tdc. If it’s out, it’ll be off a good ways. I don’t know how many teeth on those gears, but let’s say 24 teeth on a gear. That’s fifteen degrees rotation per tooth. Say thirty six teeth. That’s still ten degrees per tooth. It’s not really subtle when you see the spark off by that much.

Meanwhile, I got mine started today. I’ve got issues I think self inflicted. I bought a tank without thinking about how this engine feeds. The tank will siphon ok, and the vent works fine. The trouble is the lines are pretty small.  I didn’t think it mattered, but it appears like it does. The siphon action is designed around the 3/16 (5mm) inside diameter lines they used back in the day. The fittings on my tank are way too small. I end up with a carb adjusted at one throttle setting, but as soon as I move the throttle, it quits. Way too touchy. Just removing the large filler plug from the tank caused it to surge and die.  I’m thinking I gotta get proper lines and a different tank.

I did manage to run it enough to see that everything else seems to work.  My electric to belt drive water pump works perfectly. The water got hot, but didn’t boil. No leaks. The carb weep hole works. It dripped ON the generator I mounted under it. Gotta rethink that. Ei5her I need a drip shield, or I need to relocate the generator.   Just for giggles, I had the engine reasonably stable at a moment, shut i5 down, and slipped the belt onto the generator to give it a try.  Restarted the engine, flipped the switch connecting the generator with the USB charger circuit I’d plugged a plasma ball toy into, and plasma was had. The engine was only l7mping along when I turned on the load, so it did slow a little, but not much, and the usb worked fine, even in proximity to the CDI module.  So that’s a win.   

I’ve got plenty enough to do, lol. The connecting rod bearing not being drilled is a bummer. So that awaits.  Not really pleased with the generator location, or I need a drip shield, so my generator doesn’t set the whole mess alight. And my gas tank is a flop.

Oh, did I mention LOUD?  I had extended the exhaust with a 3 in.  long piece of brass tube clamped onto the factory head pipe. That little monster barks pretty nasty when it’s good and warm. It’s a lot louder than I’d expected.

Anyway, they call it a shakedown run for a reason. Onward.

And best of all, I got a message from our pal at DIY. Seems my last blast, which I sent to the other side, CC-d him, got under his skin. Two or three days later he wrote back.  He has proposed stepping up to the plate on the bad info on the boxer engine. Offered to replace it. I previously got no rhythm from him at all on that problem, so that’s a win.

Hillbilly T-shirt silencer 😂

Found one more for ya, Bruce.  This is a video -with bad music- that Musa posted about building the Whippet.  Hope the music doesn’t destroy your day… it nearly destroyed mine hahaha! 

Had to dig deep to find these Musa snippets about their manufacturing

https://m.bilibili.com/video/BV1rb4y1h7TL

Oh wow Bruce… that’s some great news!  I’d love to have a drill start adapter too, it’s just like the one we saw in a Stirlingkit video.  Also cool that they have 6 bolt holes as opposed to the 2 they are using in the pic haha!

It’s just like the one way bearing / clutch that’s used on my Cison V2 engines, they use a hardened steel shaft that inserts in the 1 way clutch bearing, then when the engine starts, it’s allowed to free turn counterclockwise with the engine running

My flywheel was easy to remove; a 10mm socket removes the bolt, and a gentle tap with a small plastic mallet will free it for
from the shaft.  Yes sir, the crankshaft is a tapered, keyless shaft.

By the way… my whippet hit 6 hours run time today!  Continues to run better and better, w’ lower idle rpm when I’m trying to get it to run as slow as possible.
I’m going to check it with my digital tachometer on the next run

Yours probably has more time on it than most will ever get in a lifetime. I looked at a video where someone starts a v twin with the type starter we are talking about. I still don’t get what makes the stub shaft drive the bearing then release, but it does.

Meanwhile, since I ended up absolutely hating my display mount, and I’m waiting on stuff to redo that, such as GT2 timing belt material and some M3 screws, I figured I’d go ahead and do the connecting rod bearing oil hole.  Done and back together. I didn’t disturb the crankshaft follower where it goes into the gear case, so there doesn’t seem to be any potential timing issues I don’t think.  As a precaution, I rotated the crank to the firing position, points just closing, top dead center, and scribed a mark on my nylon water pump pulley that is screwed onto the crankshaft follower, just a line pointing to a screw head nearby, so I could verify the coordination between crank and cam (points closing), essentially timing marks like a car engine has on the balancer and gear case.  At any rate, I opened up the oil hole so the splash oil dipper can “pump” oil into the bearing. That missing oil hole is I think a consequence of engineers who are not car guys. They’re urban kids in an incredibly crowded area where most people don’t have cars.  I wouldn’t be surprised if they’ve never torn apart an engine out in the world. They’re doing these projects as they would their stirling engines or other stuff, strictly from a theoretical and textbook background.  They might not even have a clue how the rod bearing on a splash oiled  engine is supposed to be. This isn’t a hit and miss or their two stroke scooter with ball bearings……………
Your reports are encouraging though. I think these little engines have loads of potential.