ESE's works engine tuner

[husaberg]

Thanks Frits - for giving me something to think about. Not in relation to 2T's but the ever more common balance shafts in 4T's. Another way to consider reducing windage in the crankcase....

How'd you secure the overlay tube ? Shrink and spotweld ?

You could always block of the shaft from the crankshaft totally and use sealed bearings.
When they were given the opportunity to design the balance shaft from scratch, they did this. no porkchops at all

Rather than below little oil covered oil beater


Here are some random Aprilia cranks.

Crankshaft balancing has been covered here some time ago. I'm sorry I can't point you to the exact page, but maybe you can find it by searching for the pictures I used:

https://www.kiwibiker.co.nz/forums/s...post1131053555
Has the links
But its all covered in tuning for speed.

[Michael Moore]

Thanks the dyno analogy made that part real clear .
But it still leaves me in the dark why over rev is detrimentallly affected by too light of rotational mass.

FWIW, I remember being told that at Daytona a higher rotational mass crank was preferred because at top speed on the banking a gust of head wind would slow the lighter mass crank bike down more and it would take longer to recover. I presume the stored energy in the rotating flywheel mass helps to make the engine less responsive to those momentary inputs (just as with a heavy flywheel weight on a classic trials bike).

cheers,
Michael

[F5 Dave]

So same thing as clutch start. Heavy resists slowing down.
Doesn't answer why it would help overrev which as Frits points out is speeding up, all while power is falling.

I've spent most of my 2 stroke tuning years working with "It just does" as it brought quick results, followed by lots of experiments to learn and gain more "it just doeses at least on this engine" junior explanations followed.

[TZ350]

how should I go about calculating the tm balance factor?

Crankshaft balancing has been covered here some time ago. I'm sorry I can't point you to the exact page, but maybe you can find it by searching for the pictures I used:

Attachment 336426 Attachment 336425 Attachment 336424

Some of the earlier posts ......

BF=(A/B)*100

A is the flywheel counter balance weight and B is the reciprocating mass (weight).

Attachment 238097

The lower half of the rod and big end can be considered rotating mass and disregarded and the upper half and little end reciprocating mass, along with the complete piston assembly.

Ballance Factor in % is A/B * 100 and is the amount of reciprocating mass counter balanced by the flywheel counter balance weight.

There is a lot more practical info in the original posts if you click through to them.

These Posts started 17th June on Page 70.

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.

Pic-1 Thomas showing of the balancing jig he lashed up in about 10mins.

Pic-2 The tubes act like a knife edges and are a very friction-less surface for the crank to roll on. The tubes are the key to the whole thing.

Try this search :- crank ballancing site:https://www.kiwibiker.co.nz/forums/s...-engine-tuner/

[Muhr]

Attachment 336423
Like this one, Muhr? There are a lot of these around, and they're supposed to be competition engines

Not so smart design with a smart solution! fun with easy-to-use solutions that are not easy to think of

One might suspect a photo editing

[wobbly]

F5 Dave - you are correct about the clutch.
When testing the BSL500 at Sepang we did a side by side test.One bike had a new AP Carbon/Carbon clutch that represented around a 40% reduction in inertia
over the normal Yamaha superbike sintered steel version.
It cost around $10,000 NZD so we were keen to prove its worth.
On the data and visually easy to see, was that from the apex of the last left hander onto the straight the AP bike pulled almost a bike length per gear change to the finish line.
The only issue was that it proved impossible for the riders to modulate the slip effectively to get consistent starts.

[philou]

[Grumph]

F5 Dave - you are correct about the clutch.
When testing the BSL500 at Sepang we did a side by side test.One bike had a new AP Carbon/Carbon clutch that represented around a 40% reduction in inertia
over the normal Yamaha superbike sintered steel version.
It cost around $10,000 NZD so we were keen to prove its worth.
On the data and visually easy to see, was that from the apex of the last left hander onto the straight the AP bike pulled almost a bike length per gear change to the finish line.
The only issue was that it proved impossible for the riders to modulate the slip effectively to get consistent starts.

When the car hillclimb crowd started using carbon clutches they found the same thing. Solved by putting a front wheel up against a barrier and slipping the clutch until it was hot. Even doing this every run, wear over a season was not measurable.

[F5 Dave]

8

Great stuff, I hope. But I was born on a remote island in the Pacific and it never occurrd to me that there would be any benefit to learning another language being that Europe was 60 million miles away.
Or something like that. French class I only learnt how to ask the time. Not how to understand the answer.

[Peter1962]

Great stuff, I hope. But I was born on a remote island in the Pacific and it never occurrd to me that there would be any benefit to learning another language being that Europe was 60 million miles away.
Or something like that. French class I only learnt how to ask the time. Not how to understand the answer.

I don't think that your French class would be of any help in translating a text that was written in Italian.

[husaberg]

I cant read French or Italian
but looking at the pic in the article I see they have still missed the point.
high inertia cranks are not all about it being heavy persay, its about concentrating the weight near the edge, so it maintains momentum, with a minimum of weight needed
but more importantly I believe it allows the inner part of the crankwheels and the conrod not to be shrouded.
Have a look at the Thiel era Aprilia pics and see there is no porkchoping no conrod cut outs.
Just narrow flat clean surfaces. Well that's what I think anyway.

Below Thiel era Aprilia no shielding of rod


I remember the first time I rode a B33 BSA whist they might not have accelerated that fast with their big heavy crankshafts, but what stuck with me was they didn't seem to slow down at all either when you rolled off the throttle.

[Muhr]

http://www.physicsclassroom.com/clas...ertia-and-Mass

http://www.calctool.org/CALC/phys/newtonian/centrifugal

[Frits Overmars]

How'd you secure the overlay tube ? Shrink and spotweld ?

Glued it. It was a carbon tube; it didn't like being spotwelded.

[Grumph]

Glued it. It was a carbon tube; it didn't like being spotwelded.

See, that's a degree of sophistication I wasn't expecting...My only experience with carbon as an engine compoment was a very short lived experiment with hand made carbon fiber pushrods....Epic fail.
Thanks Frits

[TZ350]

I believe it allows the inner part of the crankwheels and the conrod not to be shrouded.
Have a look at the Thiel era Aprilia pics and see there is no porkchoping no conrod cut outs.
Just narrow flat clean surfaces. Well that's what I think anyway.

Team ESE efforts to emulate the un shrouding of the big end like an Aprillia crank.