Balance factor

Dr_C · Dec 17, 2006

Cheers all!
Over ther years, twice I didnÃ‚Â´t make it to the finish line, due to the counter balancer bearings. So IÃ‚Â´m standing here with my eyes back and forth between the counter balancer and the bin... Before deciding, what balance factor is commonly used with the counter balancer removed? Dale spoke in 2004 about 70% +/-10% depending on application. Are there any news on this theme? IÃ‚Â´m talking about a 650 from 2003. ItÃ‚Â´s making a Supermono moving forward.

Thanks in advance!

BTW: After fine tuning IÃ‚Â´m now happily having access to 75Nm!

madero · Dec 17, 2006

hello 2 tuners I know said 65% and 67%.

So hopefully you have something on this
and 75Nm is awesome!!

Madero

Simon · Dec 18, 2006

Hi Dr. C,

70-75% seems to be a popular choice for the berg, but also 30-40%. My 01 crank is at 40% - why?, because it came out that way and I couldn't be bothered to drill & fill :wink:

I have also, however, spoken to a few people who are using an 85% factor in their singles, including some of the yamaha mini-monos to very good effect.

When I looked into the issue of balance factors myself I spoke to a motorcycle engine designer and builder, who also taught me how to balance crankshafts myself. He was of the opinion it doesn't really matter and depends more on what is comfortable for the rider. As such his list of "popular" balance factors is - 30-40%, 50%, or 70-80% and most seem to be in that region.

Cheers,
Simon

Taffy · Dec 18, 2006

from the doc:

When removing the counter-balance the crank should be re-balanced to a factor of 70% plus or minus 10% (Lineaweaver) a spacer can be made to replace the bearing or just use the inner race.

i would imagine dale is looking for smoothness in the higher echelons of the rev range. hope this helps?

regards

Taffy

LeFrog · Dec 18, 2006

I'd like to understand what you guys are talking 'bout.

Could you give me a crash course on what these percentages are?

Thanks in advance!

AUSBERG · Dec 18, 2006

LeFrog said:
I'd like to understand what you guys are talking 'bout.

Could you give me a crash course on what these percentages are?

Thanks in advance!

This explains a little bit about single cylinder crank balance/balance factors- but probably not the exact info you are after.

http://www.jmurray.id.au/balance.html

Simon · Dec 18, 2006

LeFrog said:
I'd like to understand what you guys are talking 'bout.

Could you give me a crash course on what these percentages are?

Thanks in advance!

Hey LeFrog,

Basically the balance factor is with regards to balancing the reciprocating mass connected to the crank. As you know you have a number of components that turn and a number of components that oscillate upwards and downwards.

When you do the "balance" you take all the bits that go up and down and weigh them. Then to balance them you multiply the total mass of these bits with the balance factor, get a resultant weight and that resultant weight is added or taken away from the crankshaft.

When balancing, the factor with which you do it determines the direction and/or velocity at which certain vibrations happen and by adjusting the balance factor you can tune out some of the vibrations so they are less troublesome for the engine, frame and/or rider depending on what you're looking to achieve. So the ideal balance factor depends on a number of things such as engine speeds, engine attitude in the frame, frame geometry etc. etc. etc. etc. . It obvsiously also varies with different engine components such as piston, gudgeon pin, con rod etc.etc.etc.

Generally speaking though 50% gives least load on the main bearings.

As such there is no real rule on what the "right" factor is but obviously guys like Dale have a huge amount of experience and knowledge so they've learnt where abouts is right for a particular configuration.

Singles are both the easiest and the most difficult to balance.........well actually they impossible the "balance"

Hope this helps,
Simon

Dr_C · Dec 18, 2006

Simon said:
Singles are both the easiest and the most difficult to balance.........well actually they impossible the "balance"

A couple of years ago I did some simulating in the software "Working model". I found that to be able to minimize the mechanical vibrations, you had to fit 2 counter balancers, spinning twice as fast as the crank. As thumper enthusiast are not putting "Riding comfort" on top of the wish list, I guess the BMW Funduro will be the first with this configuration, if any/ever! :wink:

LINEAWEAVER · Dec 19, 2006

"Singles are both the easiest and the most difficult to balance.........well actually impossible to balance"

AMEN!
Dale

Balance factor

Help Support Husaberg:

Dr_C

madero

Simon

Taffy

LeFrog

AUSBERG

Simon

Dr_C

LINEAWEAVER

Similar threads

Register CTA

Recent Discussions

Recent Discussions