Active Balancer for scooter engine.  By  upfartoolate (Read 2,871 times)

I haven't gotten it done yet. First, I'm having roller lifters fabricated to replace the flat tappet lifters. Baisley HiPerformance is doing that work.

Then I'll have a new cam ground to take advantage of the roller lifters (faster lift and seat, slightly longer open time). It'll also be ground to get rid of valve overlap. That'll hurt cylinder scavenging, but improve fuel efficiency. The custom expansionary exhaust I'll build will reflect a negative pressure pulse back toward the exhaust valve just before it closes (at 6500 RPM, the engine speed at highway speeds). Thus, the cylinder will have a partial vacuum locked in it.

When the intake valve next opens, that partial vacuum will help to pack more air into the cylinder by aiding in getting the air's velocity up.

Then I'll have a new connecting rod fabricated, with an offset big end. This will increase mechanical efficiency on the power stroke and reduce piston side-loading force. The new rod will be stronger than the OEM rod, so I can extend the rev limiter from 9,200 RPM to 11,000 RPM without worrying about sending the connecting rod through the crankcase.

I'll order a new OEM crankshaft, and have it and the connecting rod cryogenically treated, micro-polished and coated with tungsten sulfide. That'll make the metal less prone to stress fracture, and reduce friction.

After that's all done, I'll have it balanced. Then it'll go in the bike with the hybrid ceramic bearings I ordered from MicroBlue Bearings.

Along with the new crank and conrod, there'll be the new head with roller lifters, a new piston, and a new cylinder.

The new head will have the combustion-chamber-facing parts of the head and the exposed parts of the valves coated with ceramic by Swain Tech Coatings.

The piston will get WPC treated all over, inside and out, to remove stress risers and form a hard outer layer in the metal. Then it'll get MicroBlue tungsten sulfide on the piston skirts. Then it'll get Swain Tech ceramic on the piston face.

The new cylinder will be WPC treated, then coated with tungsten sulfide to reduce friction. The piston will get a Total Seal gapless top ring, and will run the OEM oil control ring and second ring. The rings will also be coated with tungsten sulfide.

That should make the engine run much more smoothly, give it more power due to lower friction, increase fuel efficiency and make it last much longer. But an active balancer would make it butter smooth.

I might have to end up making my own... I'll have to source mercury... it won't take a lot, just 15 milliliters, which would weigh about 200 grams. That should be plenty to balance our small engines.

I suspect they manufacture the whole thing, balance it, drill a tiny hole on the inside of the tube, inject the mercury with a syringe while the tube ring is positioned such that the hole is horizontal, then seal up the hole by brazing. Hold the tube vertical with the hole at the (inside) top, the mercury goes to the bottom of the tube, so no mercury fumes while brazing. When it's spinning, there's no interaction between the brazed hole and the mercury, since the mercury is flung to the outside of the tube, and the brazed hole is on the inside diameter. Thus no possibility of leakage.

It doesn't have to be mercury. You can use a safer material. I believe tiny ball bearings can be used as a balancer too. Don't cars have something called a harmonic balancer, like a flywheel with a rubber bushing in it?

Ok, so I did a bit of research.

Come to find out Balance Masters puts their mercury in neoprene tubing. I intend to use metal tubing for mine.

It appears that the best readily available common metal to hold mercury is AM350 stainless. It's pretty close on the galvanic scale, so there won't be any galvanic interaction between the two metals, and mercury doesn't interact with AM350 like it does with some other metals (which dissolve in mercury).

AM350 consists of the following:
Carbon: 0.09%
Manganese: 0.80%
Silicon: 0.30%
Chromium: 16.5%
Nickel: 4.3%
Molybdenum 2.75%
Nitrogen: 0.10%
Iron: 75.16%

According to the Hand Book of Chemistry by Leopold Gmelin and the paper titled 'Mechanism And Kinetics Of Corrosion Of Selected Iron And Cobalt Alloys In Refluxing Mercury' by NASA:
Mercury won't interact with carbon unless there is potash present.
Mercury won't interact with manganese unless there is chloride present.
Mercury won't interact with silicon unless there are nitrates or fluorine present.
Mercury won't interact with chromium unless there is nitric acid present.
Mercury won't interact with nickel unless there is chloride present.
Mercury won't interact with molybdenum unless there is potash and nitric acid present.
Mercury won't interact with nitrogen unless there is hydrofluoric acid and water present.
Mercury doesn't seem to interact with iron at all.

NASA tested AM350 in boiling mercury for as long as 5000 hours at 1300 degrees F, and found only a moderate surface etching and uniform wall recession with only slight surface roughening and grain transformation, with no marked changes in the corrosion zone over time or temperature... so AM350 should stand up pretty easily to mercury that isn't boiling at 1300 degrees F.

AM350 is sold in a variety of tubing sizes, is ductible enough to form it into a loop, and is readily brazed or welded to close the loop.

If I can't find any commercially available active balancers, I plan on buying some mercury and AM350, getting the AM350 cryo-treated (which increases its resistance to corrosion), forming it into a loop and welding it shut, drilling a hole in the inner part of the ring, using a syringe to put the mercury in, then brazing the hole shut.

Then I'll dip the whole thing in liquid neoprene a few times to get a thick coat. It'll slip inside the flywheel, held in place by the force fit between the rubber coating and the inner surface of the flywheel. Since it'll expand a little when it heats up (which I'm assuming it'll do with liquid metal whirring around in it at several thousand RPM, with nowhere for the heat to go since it's insulated by rubber), it'll lock itself in even tighter as it warms up.

I plan on replacing the OEM generator stator with a flywheel that has magnets embedded in it. That second flywheel will fit in the space where the OEM stator sat, and will be connected to the shaft of a proper brushless waterproof alternator, with a proper voltage regulator to replace the OEM ground-shunt regulator. That will increase the electrical generation capabilities of the bike, and save that power that would have otherwise been shunted to ground. So with the new alternator-side flywheel, there'll be room for the balancer inside the engine-side flywheel without interfering with the alternator-side flywheel.

No. I'll be removing the stator, and creating a second flywheel that fits inside the OEM flywheel, with magnets in it to transfer torque between the two flywheels. That second flywheel will be fit on the shaft of a conventional (but small) 30 amp regulated brushless waterproofed alternator that will be mounted external to where the OEM stator now sits.

This is to do away with the ground-shunt voltage regulator. The OEM setup generates power at full capacity all the time, and dumps any excess to ground, which is a waste. A side benefit is that I'll have about 10 amps more generating capacity.

So I should be able to create the balancer such that it fits inside the second flywheel, while being mounted to the first.

www.polydyn.com
From experience. These Folks for the Coatings.
Ive had some. lets say Bake the Heat Treat Right out of Pistons from the Process.
Although I currently enjoy some Skirt Coatings there not really what the marketers write it up as.

Hers a couple Ex. for ideas. Expansion or Volume gained .
First is a Pro-Circuit then a FMF