ESE's works engine tuner

[wobbly]

Why do you think you need a balance shaft.
On an engine dyno , or sitting on a kart chassis warming up - the difference in perceptible vibration between say a late model RS125 with one , and a CR125 based one , or a KZ 125 is nil , that I can feel.
The small single cylinder 125 engines balanced to around 58% do not need a balance shaft , a 50cc should be even better with way less peak amplitude forces to deal with.

[Muhr]

Thanks Wob

Yes, of course, it would do just fine without a balance shaft. this project is my little sudoku and lacks a bit of a purpose. The engine will most likely be started once in an engine dyno and then placed on the shelf.
The journey is the goal

[SwePatrick]

When i added a balanceshaft on my 212cc kawasaki i used balanceshaft and gears from 'tecate250' ,dunno exact name.
But it made it fairly simple as the gears and the splines were correct,

It made a world of difference, but on a small 50cc the vibrations will never have the same amplitude as i had(as wobbly wrote).
I revved my 66.4bore 61mm stroke to 13200rpm

But it is fun to learn as one travels forward with a project =)

[ken seeber]

Whilst balancing can make things smoother for the rider/driver, in the case of a bike or kart respectively, is there an effective power increase or decrease?

If, in the case of using a balance shaft, we add weight til we cancel out the vertical reciprocating mass. However this produces much higher 90 deg forces which we cancel out with a balance shaft. The balance shaft bearings essentially experience the same increased force as the crankshaft bearings, both leading to more friction, however small.

So, a question can be, does the extra bearing and drive friction offset the possibly parasitic power loss of shaking the frame and rider/drivers balls ?

[wobbly]

WOW , 61mm stroke/13200 rpm = 27M/s .That is EXTREME.
The tradeoff between parasitic oil drag ,bearing friction ,and added inertia Vs smoothness of operation would depend I believe on how clever the balancing was done initially.
If the wheels of the crank had been lightened , then Tungsten mass added toward the outer edge ( as was done at Aprilia ) then the added inertia of the balancing shaft could easily reduce the acceleration rate
by a % greater than the power released by having most of the final resultant forces cancel.

[jamathi]

Whilst balancing can make things smoother for the rider/driver, in the case of a bike or kart respectively, is there an effective power increase or decrease?

If, in the case of using a balance shaft, we add weight til we cancel out the vertical reciprocating mass. However this produces much higher 90 deg forces which we cancel out with a balance shaft. The balance shaft bearings essentially experience the same increased force as the crankshaft bearings, both leading to more friction, however small.

So, a question can be, does the extra bearing and drive friction offset the possibly parasitic power loss of shaking the frame and rider/drivers balls ?

I made the first 125 GP engine with a balancer shaft.
Some people said I was crazy..... it would cause additional friction.....
When I removed the balancer the engine lost 1,8HP
Later ALL 125 GP engines had balancers!!!!

[Grumph]

WOW , 61mm stroke/13200 rpm = 27M/s .That is EXTREME.
The tradeoff between parasitic oil drag ,bearing friction ,and added inertia Vs smoothness of operation would depend I believe on how clever the balancing was done initially.
If the wheels of the crank had been lightened , then Tungsten mass added toward the outer edge ( as was done at Aprilia ) then the added inertia of the balancing shaft could easily reduce the acceleration rate
by a % greater than the power released by having most of the final resultant forces cancel.

The classic assumption has been that inclusion of a balance shaft should enable a lighter chassis structure - which should enhance acceleration.

But - if there is a class minimum weight which is easily achievable, a case can be made for deleting a balance shaft...

In an ideal world with no minimum weight limits, IMO the case is strong for a balance shaft - but it's an interesting question anyway.

[husaberg]

The classic assumption has been that inclusion of a balance shaft should enable a lighter chassis structure - which should enhance acceleration.

But - if there is a class minimum weight which is easily achievable, a case can be made for deleting a balance shaft...

In an ideal world with no minimum weight limits, IMO the case is strong for a balance shaft - but it's an interesting question anyway.

Odd aside from not having a heavier chassis to soak up the vibes ALA NS/RS500 Honda .
i always assumed that the cases could be made lighter with a balance shaft design as they could be thinner as it's exposed to less vibes.


The NSR500 was given a balancer in the big bang period it was left in on the Screamer, Only as it was faster around the circuit with it in.
Likely because in a single crank set up it made it easier to turn as it cancelled out gyro.
But Doohan never cared why, only if it was faster.

I think i recall something also from Wob about CNC cases losing power quicker than Cast or something? Sealing????

[diesel pig]

I made the first 125 GP engine with a balancer shaft.
Some people said I was crazy..... it would cause additional friction.....
When I removed the balancer the engine lost 1,8HP
Later ALL 125 GP engines had balancers!!!!

Do you think the vibrations were affecting the carburator?

[ken seeber]

I made the first 125 GP engine with a balancer shaft.
Some people said I was crazy..... it would cause additional friction.....
When I removed the balancer the engine lost 1,8HP
Later ALL 125 GP engines had balancers!!!!

Jan, cheers for that. Hard to argue against an extra 1.8 hp in 53.2. A useful gain for sure.

[SwePatrick]

WOW , 61mm stroke/13200 rpm = 27M/s .That is EXTREME.
The tradeoff between parasitic oil drag ,bearing friction ,and added inertia Vs smoothness of operation would depend I believe on how clever the balancing was done initially.
If the wheels of the crank had been lightened , then Tungsten mass added toward the outer edge ( as was done at Aprilia ) then the added inertia of the balancing shaft could easily reduce the acceleration rate
by a % greater than the power released by having most of the final resultant forces cancel.

yes,, tell me about it,, =)
And it produced power also, almost 70rwhp
But wristpin and piston lifespan was very short, dunno why
I later reduced the top rpm to 11000 and it produced 64rwhp with ordinary pumpfuel

This engine will be further developed and tested this winter, i´m about to build disc inlet and with a different cylinder(TM racing)
I promise you, it is a experiance to hear that much volume in a single cylinder rev that much, like a ktm65cc but with volumeknob turned to 25(if max were 10) and still had a silencer =)

[dtenney]

WOW , 61mm stroke/13200 rpm = 27M/s .That is EXTREME.
The tradeoff between parasitic oil drag ,bearing friction ,and added inertia Vs smoothness of operation would depend I believe on how clever the balancing was done initially.
If the wheels of the crank had been lightened , then Tungsten mass added toward the outer edge ( as was done at Aprilia ) then the added inertia of the balancing shaft could easily reduce the acceleration rate
by a % greater than the power released by having most of the final resultant forces cancel.

This is an interesting result. Do you have a theory as to why the HP increased with balance shaft? A free 1.8HP is surely nice to have.....

[SwePatrick]

Fear is beeing pushed away, i needed more numbers on a sheet, so what the heck, just klick up one gear.
So, these pulls are on 5th gear, did some small adjusts before, i took away some advance and actually added some more oil to the fuel, now 6%
I also set the plug gaps to 1mm from 0.5 i had when i was looking for misfires.

And as expected, the number went up, but i didn´t expect this much
The jerky pull was from cold engine, it stuttered when i was twisting the throttle.

82.4rwhp and 90,8 crank hp together with 60,8Nm

[Muhr]

I'm convinced that Yamaha's factory team
had been ecstatic over 82.4hp at 10492 in the 90s

[SwePatrick]

I'm convinced that Yamaha's factory team
had been ecstatic over 82.4hp at 10492 in the 90s

Ever tried alcohol fuel?

I dynoed 74.9hp yesterday on 4th gear and before adjusted ignition
And E85 can add about 7-10% power if properly setup, 82.4X0.9= 74.16hp
Methanol can add even more, ive seen up to 22% on an aircooled engine.
So 10% power my blend could probably add onto 74hp, i see no dramatic way off numbers there