"If you layed all the 2 stroke tuners end to end they still wouldn't reach a conclusion"
that cracked me up
Fair weather rider
"If you layed all the 2 stroke tuners end to end they still wouldn't reach a conclusion"
that cracked me up
Long Haired Yobbo
Yet another case of funny AND true!Originally Posted by TerraRoot
"If you layed all the 2 stroke tuners end to end they still wouldn't reach a conclusion"
that cracked me up
So TZ, any plans in the works for taupo?
Heinz Varieties
Forum whore
Yep funny and Oooo so true.
Signed up for Taupo, F4 & F5. Will we see you there?
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Long Haired Yobbo
Will be there on somthing, I would like to have a bucket sorted for it but its looking like a steep hill from here. May give F3 a crack.
Heinz Varieties
125GP!!!
Might see you there. Give you the learn on the 125
BTW ; I sorted out a very temporary rear end for my bucket. Focus on other things, for now. Then ill get back too it. Pioritising! (sp?)
Forum whore
I went looking for Thomas today to see if he could shed some more light on crankshafts and balance factors.
I found him working on a classic V12 Lamborghini Miuras. The engine has just been pulled out. And yes that is four tripple throat Webbers on there.
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From Wikapedia
Early P400 Miuras, known as P400s (for Posteriore 4 litri), were powered by a version of the 3.9 L Lamborghini V12 engine used in the 400GT at the time, only mounted transversely and producing 350 PS (345 hp/257 kW). About 275 P400s were produced between 1966 and 1969 - a success for Lamborghini despite its then-steep $20,000 USD price (approx. $114,000 in today's terms).
Taking a cue from the Mini, Lamborghini formed the engine and gearbox in one casting and they shared common lubrication until the last 96 SVs, which used a limited slip differential requiring appropriate oil.
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Thomas said you can make balancing crankshafts as hard or as easy as you want it to be. You can get lost in the maths and science of it or just approach it in a practical way.
Although a single cylinder crankshaft is the hardest to get in balance but on the bright side its the easiest to work with.
He said, if he gets a chance he will explain an easy way to calculate a balance factor and also draw some pictures of a practical way to balance a single cylinder crankshaft.
He also reminded me that the engine reacts with the frame and that a balance factor that works on one bike might not work well with a different bikes frame.
Also tuning can affect vibration, poor midrange tuning can make an engine pop and bang about shaking the bike and also vibrations from the engine can send the suspension springs into a dither through sympathetic harmonic vibration.
He thinks the difference between SS90's 25% and the higher balance factors others are talking about could just be in the definition of terms.
Thomas also remarked that SS90 cut his crank to give himself more crankcase volume, the experiment was primary compresion ratio not balance factor. Thomas also said that he has seen other bikes like the RM400 with a "pork chop" crankshaft like SS90's.
First three pics are net-scrapes.
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Forum whore
that will be a tricky one to copy
Bucket Racer/Crasher
What Thomas says . . getting bogged in maths and science on a single cylinder crank is silly. Suck it and see is way easier. I have also found that frame mods affect how much vibration you get. sometimes it's better to tie the engine in good as it increases the mass and doesn't allow the vibration to build resonance for example.
On the other hand if you were building a narrow angle V6 2-stroke without a balance shaft then science has a place determining firing orders, crank phasing, and a few other things.
Forum whore
I want to know what Thomas is thinking
has he made an application to get the 4stroke limit pushed out to 4000cc ????
and how is anyone going to get past that slug anyway (or is that the plan firt to the first corner and let anyone try and get past)
do tell him that that engine will not fit in my rs frame (but we could make a really nice sidecar with it)
"Instructions are just the manufacturers opinion on how to install it" Tim Taylor of "Tool Time"
Saying what we think gives us a wider conversational range than saying what we know. - Cullen Hightower
Forum whore
Here is a real practical way to balance an inline four cylinder engine or any engine probably. Not your conventional approch but I bet it works in its own way.
http://www.vibrationfree.co.uk/engin...cing%20ppc.pdf
UTUBE vid of a crank with bob-weights being dynamicaly balanced. The bob-weights represent the balance factor chosen for this crank, or in other words how much (balance factor in %) of the reciprocating mass (piston assembly and top half of the rod) that is going to be counter balanced by the crank webs.
http://www.youtube.com/watch?v=cxWp2...rom=PL&index=5
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No8 Wire Extraordinaire
Well I have seen a bike with an off center weight bolted to the flywheel. Can't help but think that was a bit rough as 70mm from the vibration plane, but I guess may help experiment.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
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.
Thomas says it's all you need for working on a single cylinder crank and also Speedpro is right, it's very much "suck it and see".
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Forum whore
I have finaly got my head around what F5 is saying. He's right, its a rough way of doing it but probably a very quick and effective way of determining whats needed.
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Registered User
Downloading it now. Cheers.
Hardcore Biker
Yes thanks TZ and Thomas, thanks for the link.
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