V-twin engine from scratch - yet another interpretation of how (not) to build a

[madjackghengis]

Looking good Sorveltaja, if the push rod angle is too great, and that depends a lot on the depth of your ends, and how much your rockers flex on their stanchion, set your valves half way open, and your cam half way up, line the valve end of the rocker perpendicular to the valve travel, and split the angles between the rocker and pushrod, and the lifter and pushrod, and make the rocker such that all these things come to be at the same time, or are adjustable to come together at the same time.  As long as they open and close, and nothing jumps out of place, they ought to work fine.  After all Harleys run, and they don't bother with engineering.  Harley engines are still dealing with a cylinder stud problem which the Japanese bikes had figured out in the early sixties, and have never had a problem with, while Harley's still going the exact wrong direction toward "curing" their problem.  Mad Jack

[sorveltaja]

Thanks for replies .

Bit of progress:


Valves are lapped, and installed with springs, and I threaded both inlet, and exhaust ports to M5. Also flat surfaces were milled for nuts.

At this stage, everything seems to rotate and move freely when rotating manually, except the pistons are still bit tight.

Mad jack, thanks for the tips .

Making longer rocker arms might be one possible option also, to lessen the angular stress.

Forthcoming run-in sessions on the lathe hopefully reveal if such problems exist on the engine .

[Stilldrillin]

Forthcoming run-in sessions on the lathe hopefully reveal if such problems exist on the engine .

Good Luck! 

David D

[sorveltaja]

Crankshaft started to wobble during the run-in session. Reason:


One of the silver solderings failed. Similar thing happened on my previous test engine also .

I guess the reason for that is, that I have made shaft and holes too close fit, so there isn't much room for solder.

Anyways, I replaced the end axles, reamed holes to 4mm(0.157"), and drilled them partially to 4.1mm(0.161"), to provide bit more room for silver solder to flow between the parts.

[madjackghengis]

Hi Sorveltaja,  current studies show the strongest joint of this type is a technically proper press fit, lubricated with locktite, I would use 609 stud and bearing mount, and the smoothest surfaces of both the shaft ends and the holes they fit in being the last factor.  If you can freeze the shafts, heat the wheels, and make it a shrink fit with the above properties, it should be stronger than a single manufactured piece.  When I braze or silver solder such a joint, I almost always knurl the shaft ends, but avoid doing so in such circumstances that require accuracy in more than one plane as knurling allows shafts to wobble and the like.  Press fits are best served up with square shoulders to stop against, and wheels faced dead parallel to each other with either a jig or alignment pins to allow the pressing be done in one fell swoop.  If the crank is never to come apart again, you can drill holes for pins to run through both the crank pin, and the two shafts once they are all aligned, I like taper pins, and peening the small end over, after it comes out the other end.  I wish I could have discovered my shafts were not straight by running, instead of by dial indicator, at least it would have seemed like progress.  Looking good otherwise, you should have this solved in a jif, and be well running soon.- Mad Jack

[NickG]

S, nice work on the engine, looking really good now 

[sorveltaja]

New crankshaft is in place, some run-in on the lathe, and the engine is bit smoother now.

I've started to look at the carburetion part. Single barrel type was in my mind, but when looking at the heads, they have threads on their inlet ports.

I must have had some brainstorm again, since that way it's not possible to fasten single carb to two heads, without removing the other one.

Alternatively, heads might have just enough space for a short M2 screws, to fasten carb to heads.

Using a vapor carb could make whole thing much simpler technically. On the other hand, I never got it to work with previous test engine.

Maybe it just didn't have enough suction force. This time there is two cylinders, so I think I'll give it a shot.

Also the ignition is bit puzzling. Do twin engines have require two set of breakers, as I assume?

Piezo ignition is again an alternative, to simplify things, although it requires some grunt from the engine.

[sorveltaja]

Small gear made for breakers:


It was made similar way as the aluminum one earlier, except this time I did pre-cut teeth grooves with that cutting disc, to ease the 'broaching' -process.

It meshes quite well with the bigger one. A lot better than the previous alu one, before run-in. Pure luck, or I just might be on the right track on learning how to make gears .
-------------------------------------------------
Bit of an  addition:

The diamond cutting disc on the pic is really usable piece, as it cuts also HSS like butter. Some patience is required though.

Disc was attached to lathe chuck, and rotated at rather low rpm. HSS bit was fastened to tool holder, at the required angle.

I've never had that straight cutting angles on tools before.

[Stilldrillin]

Mr S,

I grind all my drills and tools, carbide & hss, on one of those 50mm discs......




Supported by a disc of 12mm ply, it has replaced the bench grinder in my shop. 

David D.

[sorveltaja]

David, I sure hope to have that big diamond disc some day .

But in the meantime, I've started to warm the piezo ignition system idea:


Plan is to make those two piezos at the same angle, as cylinders. Big gear has some extra material on its fastening part, allowing an eccentric shaft to be machined.

Piezo elements are from gas grill/owen igniter, and need about 4mm(0.157") long push to make a spark.

Those tiny ball bearings are going to be attached to piezo's moving ends.

Before that, ignition timing gears need housing to be made.

[madjackghengis]

Hi Sorveltaja,  not to disparage your pietzo ignition, which I'd like to see work for you, v-twins generally only use one set of points, a coil with both ends of the secondary available, and two lobes on the cam, firing both plugs at every point opening, the "waste" spark occuring during the exhaust cycle of the off cylinder.  Harley's did run dual points for about three years, but they were a constant adjustment issue, and went away, going back to the old way.  Have you used piezo ignition before and had success?  I've long considered it, but never got around to trying it out.  I'm interested to see how it turns out. mad jack

[sorveltaja]

Mad jack, In fact I have tried piezo ignition before, but with that engine, it was too much strain.

Seriously taken, I don't expect too much success for using the piezo ignition. One reason being, that it needs to make a one waste spark on every revolution. Other is, that can it keep up with the speed.

But who knows, testing might give surprising results sometimes .

Plan B is, that I have a traditional breaker set to replace the piezo, if it doesn't work.

I just had to make some harvesting on the net, to find more information .  

New thing to me is, that v-twins doesn't fire at the same cycle . So there is no need for two sets of breakers, or 2:1 reducing gears.

Who ever tries to build an engine, without knowing its principal functions? That's me.

It's just the way I learn things...

[sorveltaja]

I have made some attempts to make a fastening part for piezo unit, but it isn't as simple as I thought.

It needs to be made of non-conductive material. I have some round nylon bar, but it really needs extremely sharp tools. Turning went ok, but milling it is pain in the a$$ with used milling bits. So any precision is hard(impossible) to achieve.

Enough mumbling, here is the basic construction, that I'm after:


Green part is the piezo with roller, red ones are ball bearings, and blue is timing cam for piezo. An upside down U-part is in theory the part, that keeps whole thing together.

[sorveltaja]

I think I'll skip that piezo ignition for now, as it's bit difficult to fit it, on the way that was planned. It needs some troubleshooting, and more testing, that would be a project on its own.
I might get back to it though.

Next thing to do, is to fit an ordinary breaker points set. Should be a lot easier thing to do . Also they are known to work, as they did on the test engine.

[sorveltaja]

Breakers set fitting in progress:


I left some extra material for that steel plate, so that a adjusting lever can be added, if needed.

It still needs a fastening system, as it rotates quite freely at the moment.

The cam on the above pics is to be replaced, with more properly shaped one.

[sorveltaja]

Little more progression with breakers:


I machined a slot for an M3 screw, that is fastened to crankcase wall:


The screw hole was tapped and countersunk, to avoid the screw rubbing against crankshaft.

Now the breaker points set and holding plate can be fastened to engine's body.

On the uppermost pic is an M3 nyloc-nut, that takes care of fastening.

[sorveltaja]

On the right side is a flywheel, that was used on the test engine. I might mod it to fit to the current engine. Another option is to use wood and brass combination, mahogany(on the pic) or maybe plywood.

[sorveltaja]

Flywheel, and its fastening part:


That fastening part consist of brass rod and a square washer, that are silver soldered together. Washer needs two holes drilled for screws.

Brass rod will have an ignition cam machined to it:


There is enough room for two grub screws, just in case that the engine starts to kick like a mule.

One thing, that doesn't feel quite right, is that a flywheel must be attached so far from the bearing.

[sorveltaja]

Flywheel + ignition cam combo is now finished:


I also filed small flats to crankshaft, for both grub screws.

Although the flywheel might look rather crude, it's almost balanced. Fine tuning comes later, if necessary.


Next thing is to make a head gaskets from thin copper foil, as that worked really well on the test engine.

[shoey51]

i love this kind of project

[madjackghengis]

Hi Sorveltaja,  I'm really enjoying this build, despite the many difficulties, primarily because it resembles so many of my own projects.  It seems you had an idea, ran with it, hit a number of stumbling blocks along the way but simply worked around each of them, one at a time, and while what is going together isn't the prettiest engine ever built, you are definitely working through the problems, and getting down to the "nitty gritty" of design and engineering:  making the idea end up working, and not just a pretty picture, hanging on the wall.  I'm really looking forward to seeing it run, you've got a unique engine going together there.    mad jack

[sorveltaja]

Thanks for kind replies .

Whole project is a sum of compromises, as the previous one was.
In practise one could say: Use the materials, that you have available, and the tooling you already have. Be it modest or whatever, make it to happen; take the most out of it.

Philosophizing aside, at this stage, when looking at the current engine's design, crankshaft would have less stress, if the flywheel was located inside the crankcase, as it is on Hoglet(or so I assume, based on the photos, that i've seen). 

For some strange reason, I just had to do it on different way.

Same kind of oddness was noticeable, when I tried to make a fastening part for the piezo unit. I failed four times making it . Then I just stopped, and thought: 'this will not be a part for this project'. 

So back to an ordinary breaker points -schema. Lo and behold: parts for that were a lot easier to make. In fact, they are now ready to use.

Anyways, the progress of this project is in halt -stage for a couple weeks, due to renovation on my apartment.

I'll travel away, but try to lurk as often as I can.

[madjackghengis]

Dear Sorveltaja,  I was really looking forward to your attempt with the piezo ignition, but I've gone a similar route before, trying to make something work, and ending up knowing a few different ways it won't work, instead.  I know I've got piles a pieces of old projects which never worked out, but taught lessons still used today.  I know I learned a lot in all the mistakes I've made, but when I've had a project which the principles were pretty much already straight forward, just needing to be done according to how I knew, I may have got the job done, and a nice job, but generally have learned far less than I do when things go wrong.  I still have a distributor housing I made for my tractor, to use piezos, which never worked out, yet the housing and all the parts are still around, waiting for a second chance, and maybe success at some time in the future.  Keep on this engine till it runs, and then move on, with lessons learned, and new skills.     mad jack

[sorveltaja]

Finally back at home . It takes some time to get the lathe and mill to working condition, so no progress pics yet.

Also, other tools need to be spread around the apartment found.

Next step is most probably to make the head gaskets. Then perhaps sparking plugs. After that, carburetion, that is still an open case.

[Brass_Machine]

Finally back at home . It takes some time to get the lathe and mill to working condition, so no progress pics yet.

Also, other tools need to be spread around the apartment found.

Next step is most probably to make the head gaskets. Then perhaps sparking plugs. After that, carburetion, that is still an open case.

He is back! Looking forward to seeing this move forward.

Eric