\'busa crankshafts

[Guest]

Motorhead,
Piston speed is a combination of stroke length and RPM. Rod length does not have any effect on piston speed. Very high rod to stroke ratios will cause the piston to dwell at top and bottom center longer than a short rod motor and a long rod will put less stress on the cylinder walls due to its angle. For a daily use motor that needs the parts to live a long time, max piston speed should be kept under 4500 and even this requires very high quality parts. Calculating piston speed is easy. RPM X stroke / 6 = piston speed.

 

[OB_THE MOTORHEAD]

you space the base shorter rods will increase piston speed because of change in ratio between stroke and rod length this is why its recomended to increase rod length in order to keep said given speed the same.ring flutter is one of the dictators of this speed with the thinner rings in use today offer less wall friction which in turn offer less flutter at the same given speed

 

[OB_BullDog]

ah ok, I see now.. (makes sense). Is this an easier/cheaper way to gain displacement than say oversized pistions and heads?

I noticed higher compression pistions have a more oval type face on it with cutaways for the valves.. Pretty fancy stuff, ahhh ifwe all only had some money left after we bought the busa to play with the "stoke"! lol..

 

[OB_THE MOTORHEAD]

if it dwells longer does that not say its given speed of movement has been slowed down

 

[OB_THE MOTORHEAD]

seem correct in that a given distance of greater length is being traveled within the same said time frame equaling greater speed of said object

 

[Guest]

Motorhead,
The total piston speed remains the same irregardless of rod length. Acceleration varies slightly from a short rod to a long rod, but the speed achieved remains the same.

 

[OB_THE MOTORHEAD]

the rod length to stroke has to do with peak piston acceleration.peakpiston accelerationis approx.7x rpm squared,times stroke in millimeters devided by 10 million . piston accelerations of 6 to 7000g are achieved on a regular basis these days.operating within this envelope will assure the success of your setup

 

[OB_THE MOTORHEAD]

but you are correct on piston acceleration if he strokes it 3mm at 12,500 rpm w normal crank to rod ratios 66mm gives us aprox.peak pisto acceleration of about 7000g at tdc on comp.stroke 5mm is way safe as per charles Fayette taylor prof.of eng.M.I.T.good stuff that is!

 

[OB_BrainO]

Hey MOTORHEAD: Do you have a current source for Teflon/Heat Coatings on pistons? I had a set done before by a Co named Southwest Impreglon in Houston Tx, but when I called to get a set done about 3 months ago they seem to be out of business. If you have a Ph # for someone who can do a set let me know. Thanks :-) Brian

 

[OB_THE MOTORHEAD]

a friend and I own polymer specialists in cleveland we are waiting for order on fresh stuff now.has short shelf life.we do ceramic and oil retaining coatings for pistons as well as oil shedding polymers.mon or tues will have if its not there already new oven to boot hope to start coating again this or next week

 

[OB_THE MOTORHEAD]

we dont use telon we have polymers that are more wear resistant and hold oil

 

[OB_THE MOTORHEAD]

typing blows spell **** wrong all the time lately

 

[Guest]

Frank,
After claying the cases it looked like 3mm was the way to go to avoid major surgery. Also, theres piston speed and rod to stroke ratio to consider. These arent very important in a drag race only motor, but this is going to be a daily driver that I rack up miles on. I also intend to use the stock pipe to keep it looking like the day I rode it off the dealerships floor. 1500cc has got to be close to the limit of this pipe. A streetable 200HP is the goal. 1.5 litres is more than enough to get there.

 

[OB_THE MOTORHEAD]

hey neat trick this must be gnikcuf disney page sorr had to do it

 

[OB_Jay]

Gixxer;

We do not have a good one. We have one with a damaged rod journal that we will eventually repair and sell. We were keeping it for a stroker, but no one is stroking those anymore.

Jay

 

[OB_Jay]

Motorhead;

Are you the one with the stroker studs on order? Haven't forgotten. Starting on Kawasaki studs next week.

Jay

 

[OB_Jay]

Got this crank finished. Removed a full two pounds. That along with the reshaped counterweights will make a noticable performance gain.

Keep an eye on the new products section of our web site, aperaceparts.com for a photo.

Jay

 

[OB_THE MOTORHEAD]

glad your leading the way jay

 

[Frank Adams]

Jay, How much would one expect to pay for a crank job like the one you just completed?

And how much for one thats not stroked?

Thanks...Frank

 

[Gixx1300R]

Hey Jay is it true that in some applications for a lightened crank that you lose some torque?