ESE's works engine tuner

[F5 Dave]

I was thinking of an insert sealed at the sides but with a rubber as a spring at the top for 0.3mm movement of the squish. But there's a problem.
either way hardly seems worth it when you could spend your time on pipes. Like I desperately should do.

[Drew]

I was thinking of an insert sealed at the sides but with a rubber as a spring at the top for 0.3mm movement of the squish. But there's a problem.
either way hardly seems worth it when you could spend your time on pipes. Like I desperately should do.

Make me a couple for the GT too would ya.

[TZ350]

1120 already !!!!!!

Crankshaft Balancing:- http://www.kiwibiker.co.nz/forums/sh...tuner/page1121
and at the bottom of this page too http://www.kiwibiker.co.nz/forums/sh...tuner/page1120

Question for Wobbly, do you know the name of the tape, and where I might purchase this tape, as used for masking the squish area of piston pre ceramic coating (the stuff that was used by BSL before sending pistons to HPC). Thanks

As far as I know HPC made a circular mask that simply sat on the piston crown, and the ceramic was sprayed on like a paint. Then it was heat cured. Because there was a definitive line around the squish edge where the piston became flat, it was easy to align the mask.

Turns out that it is a heavy vinyl that sign writers use. You could get vinyl rings cut at any good signwriters. The areas of the piston crown that is to be ceramic coated gets grit blasted and the vinyl rings are used to protect the squish area from the grit blasting and spray application of the wet ceramic.

Wobbly, I'm a little confused. You are critical of Iridium plugs, and advocate the use of the R7376.

Now I see, in the NGK plug specification chart at http://www.ngksparkplugs.com/docs/RacingSpecs2013.pdf
that R7376 has an Iridium centre electrode.

When you criticised the Iridium plugs, were you talking about the sales name of that range, rather than the electrode metal?

Plain old Iridium plugs are a brand name, and yes they have Iridium fine wire centre electrodes. As I said, these will drop the ceramic at the slightest provocation.
The R7376 has the Iridium centre, but also has a Platinum earth fine wire strap. The construction is completely different, and is dead reliable.

The only thing that will make a plug ceramic crack and fall off is deto. In an ordinary Iridium even a few light deto pings will make it happen instantly.

A whole large batch of B9 or 10 EGV plugs the ceramic fell off for no reason, and NGK have acknowledged this in writing but I bet the importer will deny all culpability ( lawyer word for the day ).

But none of this dumb shit would ever happen if you would listen to me and use a RACING plug in a RACING engine - B7376 has never once lost a ceramic or a fine wire laser welded earth strap due to any tuning issue.

This is why they cost a bit more, still,its less of a piss off than loosing a race, and way less than the cost of a new piston etc.

Well I do like the chamfer/flat top on the piston edge ( ha hah,I showed Harold that idea when I designed the BSL500, and it ended up in the Swiss Auto,Pulse, as well ) but it also appears to have a radius,that now, we have VHM using to make better power from KZ2 engines.

But if Harold copied a certain Honda cylinder, then it for sure wasn't a late model A Kit as they ALL had very a oval Exhaust exit shape at the cylinder face that transitioned into a round within the flange to mate with the header - no step = alot more power.

Honda even issued a tech bulletin that said you would loose alot of power if you ground the cylinder round to match the
very old design spigot on the 125 customer bikes.

The best power I have ever got from a T port 125 cylinder was with a 41 wide by 32 high oval, and that was tested back to back starting at 40 round and progressively inserted/ welded and ground smaller and smaller in the cylinder and spigot.

The final design with the 41 by 32 dimensions used as cast in the cylinder - and CNC machined in the spigot made another Hp over my welded test pieces.

But shit Harold, every dumb arse could see that shaping the tang below the boost port was worth some power, allowing better flow from the reed cavity into the case area.

Hello. What you mean by "chamfer/flat top on the piston edge"? This kind of piston top: http://www.mitaka.co.uk/YAMAHA%20PISTONS/PT.05YZ125.htm ???

I have seen somewhere that the chamfer on a flat piston improves power before peak? But the head must have this shape also for the result to happen. So, with this kind of flat top on the right head shape we will have more power everywhere compared to a domed top on a Honda Cylinder?!

The Lectron 40HV flows alot more air than a 38mm SPJ but has a venturi behind the slide of 36mm.
Thus at part throttle it acts like the smaller carb.
Insanely easy to jet.
Just get a pair of 5-2 and 4-2 needles, then fine tune the high range with 40 to 70 powerjets - also makes equalising & fine tuning each side simple as well.
The TZ400 when it ran at PI had 4-2 with 85/90 on top, so I will now go to 5-2 and drop down to around 50 powerjets.
And when you want to go sex plus I have made some inline solenoid bodies that will switch the PJs from Ignitech.

Cheers. So what is the off throttle fuel feed like? I sort of like having the rich pilot when the brakes are on into a corner.

Rich wants simple - APTs need alot of dicking around to get even close as they dont have a big matrix of needles with top end and mid
taper changes.Makes tuning a twin more than twice as hard.
Plus no fine tune powerjet.
The trick venturi shape is more suited to great throttle response for say buckets on a kart track, or MX.
They have apparently recently done some more needle combinations, but I havnt had time yet to look into this.

Re the Lectrons bottom end tuning on the overun Rich,simply turning the rod in 1/4 turn increments makes for super easy changes in off idle fuelling.
And as I said about the TZ400, it had 4-2 needles with big powerjets, so simple next step is a 5-2 with smaller PJs - will end up with same egt and better part throttle corner response.
No effect on the bottom or mid tuning, just rearranging the top end.
The 300 motors will end up making some more power than the old TZ based 400s - 86RWHp so that motor is a bit overcarbed, but the HV venturi helps the mid response a heap.
One of the 300 customers wants some 38PJs so maybe you can do the Lectron thing for no outlay.

... reminds me of the man who went to a fortune-teller to get some palm-reading done. The palmist promised him he would meet a gorgeous woman and get married. The man replied: "Some palmist you are. I got married to her allright. And divorced too!"
The palmist said: "What do you expect from me when you never wash your hands."
It's the same with spark plug and piston reading.

This >> https://www.facebook.com/Techgp/phot...=photos_albums

http://tyga-performance.com/site/index.php?cPath=73_191 and I see prox do a kr150 piston.

Bucket Racing at Edgecom http://www.kiwibiker.co.nz/forums/sh...1130838589#top

Interesting workshop projects:- http://forums.everything2stroke.com/...he-Shop/page46

dimensions for a Honda RS125.

Carb manifolds
http://www.jetsrus.com/mounting_flan...g_flanges.html
http://www.allensperformance.co.uk/p...manifolds.html

Attachment 309622

A loncin after market CDI stator converted to a 12V DC generator for the Ignitec

http://www.aliexpress.com/item/Perfo...731580291.html

Watch out for these, my one failed, that was my issue at Taumaranui, the rotor was moving in relation to the taper.
The taper wasn't slipping, nor were the rivets but it broke between the taper and the part that rivets to the rotor in such a way that it appeared normal until under heavy load, then it would move.

I am posting far to much and doing far to little but I found these as the CR125 ones will get harder to find.
Ktm125-300 seem to have a nice small rotor stator Kokistan with 25 watts or 50 watts aftermarket
http://www.cafehusky.com/threads/08-...-do-that.2755/
Attachment 309628Attachment 309629Attachment 309630

http://www.thumpertalk.com/topic/930...200-flywheels/
http://www.rmstator.com/en_ww/produc...om_store=en_ww
http://www.ebay.com/itm/NEW-KTM-125-...-/221120717793
pretty sure it might be very similar to the Honda cr one
Plus I also found these.

Its an outer rotor from HPI
http://www.hpi.be/210.php
http://www.hpi.be/item.php?item=210K008
https://www.treatland.tv/PUCH-HPI-CD...old-used-2.htm
Attachment 309625Attachment 309627Attachment 309626

You cant use the old CDI cheater trick with a PVL.
It uses the same coil to charge the capacitor on the N pole magnet ,then triggers the output circuit with the S pole using that same coil.
In the usual systems of old there was a charge coil, and a separate trigger .
If you simply put a small value capacitor across the trigger this would completely change its inductive reactance curve.
In old TZ350s we could set the static at say 4mm, and the cheater trigger mod would pull it back to 1.5mm at 10,000.
The same idea can be used to cheat the ignition timing in some kart classes but I know nothing about any of that.

Thanks for your explanation Wob.

Attachment 309598

At first I had trouble getting my head around their graphs, they did not make sense until I realized that the "0" line represents the static timing point which could be any number of degrees one chooses BTDC and their curve moves + and - relative to that point.

Attachment 309597
As I now understand it, in this graph, if the initial timing was set at 15 deg BTDC then "0" on the graph means 15 deg BTDC and at 2000 rpm the real ignition point is 15 + 3 = 18 deg BTDC, at 8,750 rpm it is 15 + 0 = 15 deg BTDC and at 12,000 rpm it means 15 - 3.5 = 11.5 deg BTDC.

Also things can get confused when using a timing light because the trigger circuit in the timing light has some capacitance and therefor some delay in flashing the light after the triggering event. This has the effect of the timing appearing to be more retarded than it really is. At low rpm when there is plenty of time this error is very small and not much of a problem but at 9 - 10,000 it can get very noticeable and at 12 -14,000 significant.

Exaggerated retard due to the timing light flashing late, is just another thing to watch out for.

Adding a 0.47mfd/200V cap across the trigger will create around 1*/1000 rpm retard.
So with around 6mm static I think it stared at 35* and by 10,000 it had 1.6mm = about 17*from memory
Thus the old pretty much straight line became a crude retarding unit, with extra mid advance for drive, and extra retard over the pipe for overev.

http://www.kiwibiker.co.nz/forums/at...2&d=1319412316
He used to do a roaring trade in them
last paragraph first page below. keep clicking on it till it is large enough to read
http://www.kiwibiker.co.nz/forums/at...1&d=1319423423
http://www.kiwibiker.co.nz/forums/at...2&d=1319423495

I can't remember what the variable capacitors are called but they used to be in radios.....
Attachment 309650


555's are useful little beasts........But to map them would take a set up like wobs...
Post it again Wob

oh I found it once I figured out how to spell vacuum





Attachment 309651

I used NGK R7376-10 racing plugs ( I use them in everything ) as these are same plug as is sold in the shorty version for
GP bikes with special cap for silly money.
But these plugs are normal body size,and have the Iridium electrode and Platinum small ground wire for around 40usd.
The NGK racing plugs have special resistors in them.
The 5K plug with no cap resistance and Magnecor 10mm wire works a treat with no RF problems for the Ignitech.

I use Ditex ignition test gear into my laptop.
Here is a video of the twinfire with Crane PS92N enormous cdi coil, on my test rig with CR125 stator/rotor/reg/cap.

http://www.youtube.com/watch?v=pA6kjjEMiaw&feature=plcp

Its a vacuum cleaner motor with a light dimmer rheostat and reverse switch for speed and direction.
Small toothed belt drive so I can use a big degree wheel on one end of the shaft and the ignition on the other to check timing curves..
Shaft slides in and out on eccentric lock bearings to position the rotor correctly.
I have seen nicer rigs using spindle moulder motors, but the old Hoover motors are free.

Here is a pic of cranks for Aprilia 250.
Full circle, full width, plenty of Mallory, high inertia, very low in cycle speed variation, lots of power and overev - why isnt your crank like this??

Also pic of my Ignition rig.
A vacuum cleaner motor with light rheostat, also reversable, has protractor on the other end.
I use a cheap kart rev counter and a strobe.
Doing curves on anything is easy, once its set up.

Attachment 309599Attachment 309600
A couple of pictures for you all

Look carefully at these photos and you will see that the exhaust port floor is higher than BDC.

12v water pump epic output
https://www.12volt.com.au/
Circulation Pumps

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Suitable for fresh or salt water, bilge water and mild chemicals.

Not self priming - install below the liquid source.

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•29 GPM - 110 litres per minute flow

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•3/4" female BSP female threaded ports

•12 volt 8 amp Cyclone pump

•24 volt 4 amp Cyclone pump
Jabsco Cyclone Circulation Pump
PUJCY12V Cyclone 12v $539.00


12VDC 8A Dimmer / Motor Speed Controller

DC speed controllers are ideal for slowing down pumps and motors or dimming lights but commonly use resistance circuits and are very inefficient.

The pulse width modulation (PWM) used in this controller allows you to vary the output from 0 to 100% while maintaining a very high efficiency.

When used on motors this ensures full torque is available at very low speed and the motor won't shudder at start-up.

Operates on any 12VDC system and capable of controlling devices rated at up to 8 amps.

The internal circuitry is fully potted and the control potentiometer is splash proof making this suitable for marine environments and other harsh conditions.


Dimmer / Motor Speed Controller
MP3209 8A 12VDC dimmer $39.99

[wobbly]

Yep, the concept of the system used by Team Roberts was admirable, but as Dave points out the dynamic squish in reality varies with rpm and I will add, bmep.
Making the head retract as the cylinder pressure increases against a set pressure above the insert is clever, but as is the usual case, no free lunch.
Squish clearance needs to vary with rpm ( and by default bmep ), so having the chamber fixed in space to the cover, and the squishband area moving independently
seems a really great lateral thought process that ticks all the boxes.
Minimising the end gas volume at all rpm, via a variable squish height, but having a fixed chamber would then give high com and high squish at low rpm ( bmep )
then translating into slightly lower com, along with low squish volume at high rpm ( bmep ).
Dropping the com as the engine comes onto the pipe, maximises the energy distribution as we know is actually needed, but at all times the squish volume is minimised - brilliant.
Having the close tolerances needed along with O ring seals wont affect the temp gradient we want ie a cold squish area, and a warmer chamber, if the thought process of the really effective squish cooling
scenario I have alluded to is used as well.
Hey, hey, maybe a small step for Dave, a giant step for 2T technology, good shit.

[F5 Dave]

Great, now make me a pipe and you can keep the patent.

[wobbly]

Yea right, the variable squish concept took 2 moments of intellectual input - doing your pipe will take 2 days of sim and then CAD.
I will post you my account details.

[F5 Dave]

And when I only had to support myself that would have been a good idea.

[seattle smitty]

Very interesting discussion here, which I'm trying to wrap my remaining neurons around . . .

In talking about squish clearance, you're talking about accommodating the stack-up static tolerances of all the moving parts involved, plus the "growth" of the assembly with rpm; the neat rotating and reciprocating we see when turning the assembly over by hand, becomes a mad wriggling and flexing and loading/unloading in every axis, if we could see it in stop-motion with a stroboscope. You can't (anyway I can't) plug basic engine dims into a formula for determining squish clearance . . . b/s, rod length, weights, rpm, compression, there'd be no end to it, and how would you account for all the different ways various manufacturers build the crankshafts and how they support them with bearings and how much their cases might flex, OR know the rpm bands you have to pass through at which there are harmonic convergences that amplify the shakes and flexing even more! With the complexity and innumerable variables here, I don't see how anybody could write a program that would reliably tell you ahead of time that at 8500 you'd need X amount of squish clearance, while at 9500 you'd need X plus .0012", at 10,500 you'd need . . . and so forth. You couldn't plug in other numbers, an increase in rod length, or a heavier flywheel, or a lighter piston, and have the program re-plot your squish-clearance needs throughout the powerband.

But, if I try to list all of the parts, all the clearances, and all of the effects, as if I were going to write such a program, I can start seeing places where I might make some change, the goal being to reduce the highest amount of squish-clearance, the clearance I have had to build into the engine. Do I have room to replace a single-row with a double-row bearing at one end of the crank (and still have room for a seal?)? That's an actual example of a thing I was able to do on a very old 250cc Konig, and required adding material to the crankcase before I could bore it out for the longer bearing-plus-seal. Can I lighten a piston or a wristpin? I know that miniscule reductions in weight become big numbers at racing rpms. Aannnd so forth.

But the part of this I wonder most about is the design of and balancing of crankshafts. Car racers send their stuff off to a balancing specialist without a second thought. Maybe you guys do too, but in my out-of-date experience, 2-stroke racers, or at least outboard racers, mostly just use the parts as they came from the manufacturer. Maybe some of them will match-balance their pistons, and a set of rods end-for-end, which you can do with a gram-scale and homemade fixture to hold the rods. But as to assembling and truing a crank and sending it off to be balanced, I think everybody I knew didn't want the hassle of pressing it apart again, installing rods/bearings, and re-truing (never much fun), and most of us knew little or nothing about "balance factors" and Mallory-metal and other higher-order balancing considerations. We just figured it was "close enough." Well?? Is it?? Are you going to tell me (I hope) that you Kiwi bikers are miles ahead of us in this realm of technology, and you know all about it and build it into your engines?

For instance, take a 125cc single. What we hear is that you can't balance a single, it's going to shake and the best you can do is the move the imbalance around to where the shaking engine isn't hammering the frame mounts, the rider's hands, or the engine's own components. But you can look at different motors and see differently sized and shaped and balanced cranks. Presumably, as with all other aspects of engines, some of the manufacturers have done it better, some not so well. How does an owner, especialy a racer who does his own wrenching and modifying, look at it and know? Maybe if he carved some metal off the corners of the crank, or had a slug of Mallory metal added to the crankshaft or a flywheel, he could reduce some of the high-rpm shakes and thus need less squish clearance. If by doing this you could reduce the amount of squish clearance you have to add in going from 8500 to 12,500, you'd have at least reduced the problem that has been under discussion for the last few pages.

Has anyone written about balancing 2-strokes? Not the usual quickie but at length, and in language accessible to amateur racers who are not engineers?

Counter-balance shafts would be part of the extended subject. A few engines, singles, have them, but more of us might want them, since they reportedly don't take a significant amount of power to operate. Guys here can build anything; how can we figure out how to design ourselves a counter-balance shaft? For a single? For an opposed-twin, for a parallel twin, for an inline triple (notable shakers, sometimes)?? Guys here are adding rotary valve valves and drives to their reed-fed engines, and a disc rotary valve is unbalanced, and must add a bunch of shake when spun up into five figures. How do we counter-balance that shake? Depending on the plane of the rotary valve, it very well might add to the squish clearance needed, especially in one of those transitory harmonic convergences.

Certainly the first reaction including mine, is "Oh balls, this is way over-thinking, it's close enough, the real answer is another beer!!" But if we thought this way all the time, this thread of TeeZee's would not exist . . . .

And then Dave wouldn't have come up with his floating squishband idea . . . pretty cool, Dave, but what I would hope to do with the suggested re-balancing and counter-balancing is reduce the distance your gizmo would have to float.

[F5 Dave]

All I came up with was the conclusion I needed to spend more time on the basics

Try your luck with the search feature, balancing has been covered before, but 1100 pages needs a computer and TZ's page summaries.

[wobbly]

You dont need a pile of code to do engine balance.
Its been established for a long time that a factor of 55 to 58% where the cylinder is reasonably close to vertical in a 2T is on the money.
Due to the huge masses involved with big dumb arse 4T things they overbalance to near 80% in something like a Norton Manx to stop the vertical
vibes of the handlebar/chassis assembly making the riders complain.
Its all to do with minimising vertical shake at the bars in a bike,but a similar action affects karts as well.
You dont need a balance shaft in a single 2T as plenty of them have been made with no issues of vibration at all.
In a parallel twin you need one if firing at 90* like Harolds KTM as this reduces the rocking couple cancellation action of a 180* firing.
But yes a balance shaft has been used in things like RS125s from Honda, and these are set up to cancel the unbalanced portion of the reciprocating mass.
Take the shaft out and rebalance with Mallory and are they faster - yes.
Add some more Mallory to create a higher inertia crank assembly without affecting the balance and are they faster - yes.
Just a bit more to think about.

[2T Institute]

http://www.ebay.com.au/itm/Woodland-...item4190b30113

Here are some screw in tungstens 14g/ half oz each net add should be 11g

[speedpro]

Honda MB100s have a balance shaft. I have removed the balance shaft in one motor and rebalanced the crank. The balance shaft rotated in the opposite direction to the crank at the same speed. It assisted the crank counterweight in offsetting the forces in line with piston motion but opposed the counterweight effects at 90degrees to bore centreline. Obviously I had to increase the crank counterweight which I did by drilling a couple of holes in each web, one each side of the big end. It buzzes a bit at odd speeds and you have to be careful how the engine is mounted to reduce harmonics.

[husaberg]

Has anyone written about balancing 2-strokes? Not the usual quickie but at length, and in language accessible to amateur racers who are not engineers?

Counter-balance shafts would be part of the extended subject. A few engines, singles, have them, but more of us might want them, since they reportedly don't take a significant amount of power to operate. Guys here can build anything; how can we figure out how to design ourselves a counter-balance shaft? For a single? For an opposed-twin, for a parallel twin, for an inline triple (notable shakers, sometimes)?? Guys here are adding rotary valve valves and drives to their reed-fed engines, and a disc rotary valve is unbalanced, and must add a bunch of shake when spun up into five figures. How do we counter-balance that shake? Depending on the plane of the rotary valve, it very well might add to the squish clearance needed, especially in one of those transitory harmonic convergences.

Phil Irving tuning for speed........
google has it
http://tuningforspeed.com/files/Tuning_for_Speed.pdf.

.

Measuring the balance factor of our Suzuki GP125,s

The round bar is very nearly as good as knife edges.

Pic-1 Finding the counter balance by hanging washers of a hook attached to the conrod.

Pic-2 Determining the mass "C" of the counter balance.

Pic-3 Determining the mass "R" of the reciprocating weight.

The balance factor B = C counter balance mass divided by R reciprocating mass.

The balance factor is.......B = C / R

As measured by me, it turns out that the balance factor of:-

A standard Suzuki GP125 is 69%

A Standard Suzuki GP100 is 76%

A GP with alloy plugs in the counter balance holes becomes 58% for the 100 and 52% for the 125.

When we recently dyno'ed two of our bikes with cranks that had the same 69% balance factors. The RS frame vibrated much more than the original GP frame did.

For us this supported the notion that there is no one correct balance factor, as the right balance factor is the one that works with the frame that the motor is mounted in.

I think it was SS90 that said that the balance factor that works best in a high output 2-stroke will tend towards 50% as the rev's go up. And we found that, that pretty much happened. When we put alloy plugs in the crank balance holes to raise the primary compression ratio. As an unintended consequence the balance factors changed and become less 58-52% and the engines became noticeably smother at higher rpm.

I asked Thomas about this and he said that motors with a wider spread of power and that are operated over a wider rev range like the std GP engine tended to have a higher balance factor than ones with a narrower power band like our hotted up engines. That made sense when you look at the Kawasaki 250 & 500 4-stroke MX bikes that have a BF of 60% and the big 4-Stroke cruisers & sport bikes at 70+ %.

It seems that the wider the rev range the motor is going to be operating over the higher the suitable balance factor will be. Its easy to relate this to the Kawasaki 4-stroke 250 Mx bike, same revs but wider power band, and a BF of 60%.

I have a Honda RS125 crank to look at next, I suspect it will be 50% but for different reasons.

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving. http://www.scribd.com/doc/15392252/T...rcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

The balance factor is C / R

.

I was able to weigh the RS crank the same way and the crank itself came out at 50%. The counter balance also looks to represent 50%.

I don't have all the RS here but after looking at the H100. The way I think it works on the RS is that the counterbalance spins twice as fast as the crank.

I said the counter balance "represents 50%" as I don’t think it weighs 50% but because it spins twice as fast as the crank its inertial mass becomes 50% as it spins around.

This allows the counter balance to work with the crank top and bottom to cancel out the piston and then it cancels out the counter weight of the crank mid stroke twice a revolution.

So it goes something like this.

Top:- Cranks 50% plus Balance Shafts 50% going down together cancels the Pistons 100% coming up.

Mid going down:- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions.

Bottom:- Cranks 50% plus Balance Shafts 50% coming up together cancels the Pistons 100% going down.

Mid going up:- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions again.

To do this the Balance Shaft has to rotate twice as fast as the crank.

So in theory you get a 100% balancing of the engine but really its just a bit of clever push and shove. As the crank is still 50% out of balance and when it pushes side ways the counter balance shoves it back and then twice a revolution the two of them gang up on the piston and pull it back.

It looks like the engine is balanced but there are really a lot of stresses going on inside.

I am not sure how you would go about matching the counter balance shaft to the crankshaft without making some comparitive weight measurements and doing some maths that takes account of changes in inertial mass with changes in rpm as it would not be a simple 50/50 weight thing for the whole rev range.

As the inertial mass of the counter balance shaft will change more than the crankshaft does with changes in rpm. So I guess you tune the weight of the counter balance shaft to work best in the rev range you want to use.

The balance factor of the RS crank is C/R = 50% of the reciprocating mass.

.

These Posts started 17th June on Page 70.

(2) Describe how to find the reciprocating weight.

Looking at the connecting rod it is easy to see that the Big End goes round and round and is all rotating mass. And the little end goes up and down and is all reciprocating mass.

But the bit in the middle is not completely either, it does a sort of wiggley motion. You can worry your self to death over it or just take a good old practical common sense approach.

Pic-1 shows the crankshaft divided into "Rotating Mass" on the left and "Reciprocating Mass (weight)" on the right.

Pic-2 shows the Reciprocating Mass (B) being weighed. When weighing its important that the conrod is level and only the little end touches the scales.

Pic-3 On these cranks its easy to see the counterbalance’s but in others you just have to imagine where they are as the can't be distinguished from the rotating mass.

The Rotating Mass within (A) naturally balances itself and is not involved in the crankshaft balancing process.

External items like Magneto Rotors, Generator Flywheels and in Cars Harmonic Ballancers/Flywheels/Clutches are fitted and ballanced after the crankshaft itself has been balanced. The crank is balanced first then the other round bits are fitted and balanced later.

In balancing the crankshaft there is only "Reciprocating Mass", "Counter Balance" and the "Balance Factor" which is the relationship between them.


Let:- "Counter Balance" = A "Reciprocating Mass" = B and "Balance Factor" = C

Then A = B X C .............now this is a real formula complete with a definition of terms.

This formula gives you the Mass (weight) of the Counter Balance if you know the Reciprocating Mass and the Balance Factor you want to use.

This is not new, Speedpro has allready posted hand drawn pictures like this, showing how he did it.
.

.

The KISS method of balancing a single cylinder 2 or 4-stroke.

Its all in the pictures:-

Pic-1 Find the total reciprocating Weight (Mass)
Pic-2 Find the Little Ends reciprocating Weight (Mass)
Pic-3 Find the Balance Facter (Ie. 65% is 0.65 X the ToTal Reciprocating Weight (Mass))
Pic-4 Leave the Little Ends reciprocating Weight (Mass) on the Scales
Pic-5 Attach the rest to the crank.
Pic-6 Balance the Crank.

From Phill Irving. page 109 "the wheels will roll freely along the straight-edges and show no tendency to settle in any one position; if not, the pin will go to the top or bottom according to whether the Counter Balance is to heavy or to light. Correction is usually made by drilling the rims."

Very simple, very effective, a very accurate way to balance a single cylinder crankshaft staticaly. If anyone can come up with a better static balancing method, Thomas and I would like to hear about it.

To find the existing balance factor of a crank shaft, you just more or less work through this process backwards.

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The percentages quoted are "mass".

The forces generated by the reciprocating mass increases linearly as a function of the rate of reciprocating.

The force generated by the rotating mass increases as a square of the rate of rotating.

Therefore, even though at standstill the rotating mass only exerts a force equal to say 60% of that exerted by the mass of the reciprocating parts, as the engine speed increases the forces generated by the rotating parts increases at a greater and greater rate and eventually equals the force being generated by the reciprocating parts. If engine speed continues to increase the forces generated by the rotating parts will exceed the forces generated by the reciprocating parts. The forces mathematically only equal each other at a single engine speed. We want that speed to be close to the operating speed.

On a single the forces at 90deg to the cylinder bore are unopposed regardless of the % used as there is no force generated by reciprocating parts to oppose them. 90deg V-twins are wonderful.

Frits Posted an extract from Tony Foale site about counter balancers

Here

You may, Husa. The picture below may give a first impression, and you'll find the whole story here: http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf
Attachment 282158

Another thing to consider is fueling can be less fraught if it isn't being vibrated about too much.

You dont need a balance shaft in a single 2T as plenty of them have been made with no issues of vibration at all.
In a parallel twin you need one if firing at 90* like Harolds KTM as this reduces the rocking couple cancellation action of a 180* firing.
But yes a balance shaft has been used in things like RS125s from Honda, and these are set up to cancel the unbalanced portion of the reciprocating mass.
Take the shaft out and rebalance with Mallory and are they faster - yes.
Add some more Mallory to create a higher inertia crank assembly without affecting the balance and are they faster - yes.
Just a bit more to think about.

I await The Dutch corospondents reply.

[F5 Dave]

Honda MB100s have a balance shaft. I have removed the balance shaft in one motor and rebalanced the crank. The balance shaft rotated in the opposite direction to the crank at the same speed. It assisted the crank counterweight in offsetting the forces in line with piston motion but opposed the counterweight effects at 90debrees to bore centreline. Obviously I had to increase the crank counterweight which I did by drilling a couple of holes in each web, one each side of the big end. It buzzes a bit at odd speeds and you have to be careful how the engine is mounted to reduce harmonics.

I pretty much copied Mike here with a different frame and buzzes a bit somewhere maybe between 4000-8000 (not all of it) but I should never be there & over 30min race I never noticed vibration, so its great at race revs.

[Farmaken]

Wobbly, what is the total weight difference between a std. RS crank and a "heavy " version with heavy bar inserts. Cheers....