Two-stroke performance tuning?

[FastFred]

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"Yes changing a cranks shape by say cutting a piece off it will change both its balance factor and the primary compression ratio."

Then rebuilding the cut with a lighter material like devcon will restore the primary compression ratio to what it was but not the balance factor.

the ballance factor or changes to the balance factor does not affect the primary compression ratio, crank shape does.

Go on SS90 do tell us what "Balance Factor" means, have a go, define it for us.

Use a formula if you want, you know what a formula is don't you?

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[SS90]

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Then rebuilding the cut with a lighter material like devcon will restore the primary compression ratio to what it was but not the ballance factor.


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Bahahahahahahha

When did I say that?

[FastFred]

No you didn't say that, I did. You havn't sufficent insight to understand it.

Still no formula for "Balance Factor".

[FastFred]

Geee,

You havn't been following there have you?

I will write this REALLY SIMPLY.

Crankshaft balancing is simply the term used to describe changes made in the counterweights (webs) of the crankshaft to compensate for the weight of the moving components including the crankshaft,rod,piston,rings,gudgeon pin,clips.

The "factor" is simply a way of expressing this "counter weight" on the crank
compared to the weight of the piston rods assembly.

i.e the piston/rod assembly weighs this percentage of the crankwebs (counterweights)

What weight you chose (primarily) dictates what RPM the engine is best "balanced"

Getting closer.

I see you have had a quick read of Phill Irvings book but he puts it better and correctly.

You've more or less said it but lets see what you've understood.

Now tell me which is heaver, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.

SS90 this is the test (A) or (B).

[SS90]

No you didn't say that, I did. You havn't sufficent insight to understand it.

Still no formula for "Balance Factor".

My god.
How old are you Bucketracer?

You are the only person on this thread that can't see that just by changing you log in name, you don't get any smarter.


I already posted the formula for calculating a balance factor.

Last week.

You pointed out that it was indeed an "arithmetic sum", not an "equation" as I had called it.

Perhaps you can be so good as to explain the breakdown of the relevent figures for us all?

I.E, what number represent what part of the engine?

You seem to be calling my experience (and intelligence) into question.

That would suggest you know what you are talking about.

Come on, don't be shy.

[FastFred]

You seem to be calling my experience (and intelligence) into question.

"Intelligence is the ability to learn."

SS90 lets test your intelligence.

So once again, which is heaver, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.



(A) or (B) SS90


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[FastFred]

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One is a % of the other, when SS90 can correctly workout the answer to the question, he will have finaly come to an understanding of "Ballance Factors".

Well maybe he will get it or maybe not, if not, my work here is done, because you can't spend forever trying to help the terminaly stupid. I am off for a pint and to tell my brother how this went.

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[bucketracer]

Your confusing the "Balance Factor" the crankshaft has been made with, with its "Physical Shape".

Physical Shape is not the same as Balance Factor.

Physical Shape has a bearing on primary compression ratio.

Balance Factor has a bearing on how much of the reciprocating weight is counterbalanced.

And they are completely different things!!!!!

Again.....Bahahahahahahahha!

Removing the material from the correct place of a crank does TWO things

1) it changes it's physical shape (and volumetric displacement...physical SIZE)
2) it changes it's balance factor (the factor you get depends on how much you take off, and from where)

What are you not understanding?:

SS90 in your confused bumbling way you have eloquently demonstrated that engineering is almost always a compromise, that changing one thing invariably affects something else. Like, if you change the balance factor you have to take some corrective action to maintain the same primary compression ratio. Like plugging the new balance holes or putting tin covers over the crank wheels like in the Honda RS125.

When changing the balance factor, means changing the crank shape, this affects the primary compression ratio. This is the problem of unintended consequences that comes from changes to one thing affecting another and its traps like these that all engineers before Phill Irving and every one since has had to deal with.

The unintended consequences of changes to the balance factor, affecting the primary compression ratio may be a modern problem, but SS90 there is NO so-called “Modern understanding of Balance Factors” in your posts here. But there is a lot of verbage and a few photos of cranks that have different shapes but could have the same balance factors, demonstrating what I have just been saying about the age old engineering problem of how one thing can impact on another.

Every engineer or tuner needs to be consciously looking out for how the changes they are making will affect other things in the system. There are some new traps with modern 2-strokes but the crankshaft still goes round and round and the piston up and down, basically, other than the occasional balance shaft nothing much has changed for a single cylinder, 4 or 2-stroke since Phill Irving wrote that chapter on crank balancing.



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[saxet]

SS90 in your confused bumbling way you have eloquently demonstrated that engineering is almost always a compromise, that changing one thing invariably affects something else. Like, if you change the balance factor you have to take some corrective action to maintain the same primary compression ratio. Like plugging the new balance holes or putting tin covers over the crank wheels like in the Honda RS125.

When changing the balance factor, means changing the crank shape, this affects the primary compression ratio. This is the problem of unintended consequences that comes from changing one thing affecting another and is something all engineers before Phill Irving and every one since has had to deal with.

The unintended consequences of changes to the balance factor, affecting the primary compression ratio may be a modern problem, but SS90 there is no so-called “Modern understanding of Balance Factors” in your posts here, just the age old engineering problem of one thing impacting on another. Nothing much has changed since Phill Irving wrote that chapter on crank balancing.

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Is'nt this what ss90 has been saying all along, are you even reading this??

[bucketracer]

Is'nt this what ss90 has been saying all along, are you even reading this??

No, I don't think so. Sure he may have talked about one thing affecting another, but the way I read it, he explains it as a modern understanding of the relationship between balance factor and primary compression ratio and that juggling the two implies a new modern thinking that makes Phill Irvings work old hat.

Where I say more correctly I think, that changes to the physical shape of the crank to achieve a different balance factor has an unintended impact on the primary compression ratio. And that juggling the two is the age old engineering problem of compromise and Phill Irvings book is not as old hat as you might think.

If I am wrong please explain it to me.

[Ned Kelly]

Which is heaver, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.


(A) or (B) SS90

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I have been looking everywhere for the answer to this. Does anyone know the answer?

SS90 help us out here. Thanks.

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[Buckets4Me]

Geee,


i.e the piston/rod assembly weighs this percentage of the crankwebs (counterweights)

What weight you chose (primarily) dictates what RPM the engine is best "balanced"

so the crankwebs are heaver so the answer is B

thanks SS90

piston rod = 25% of crankwebs (counterweights)

[bucketracer]

so the crankwebs are heaver so the answer is B

thanks SS90

piston rod = 25% of crankwebs (counterweights)

"the crankwebs are heaver" Seriously is this what SS90 Thinks............Your not making it up?

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[Fastborisracer]

Is'nt this what ss90 has been saying all along, are you even reading this??

No, I don't think so..

[bucketracer]

My god.

How old are you SS90?

Are you the only person on this thread that can't see that just by changing you log in name, you don't get any smarter.

But I like it.

Lets play a game where we see who can make the other look the bigest dickhead. I know your trying hard but I am winning so far.

We could even start a pole!!!!

Now lets see, we could discuss something that you don't know anything about like 2-stroke tuning and engine ballance, while you flounder through it we trade insults and the public get to vote on things like imaginative input, creative crap about modern ballance factor thinking and sheer stupidity. And along the way drop a little gem about something technicall and interesting here and there, should be fun, are you on???

Ill start, So which is heaver, (A) the reciprocating weight of the rod piston assembly or (B) the counter weight of the crankshaft.

PS Fastborishracer the public are still waiting for your answer (A) or (B) ? Mmmmm don't know do you.

And this is the crux of "Ballance Factor"

Now neither SS90 or Fastborishracer is telling us, thats not fair, them being so smart and all.

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