Hey guys and girls
Came accross a forum post with some interesting info.. It seems that the guy knows what he's talking about..
If you prefer the link, here it is:
http://newsgroups.derkeiler.com/Archive/Rec/rec.motorcycles/2007-06/msg02060....-------------------------------------------------------------------
Sean wrote:
The single cyl Suzuki Boulevard S40 (aka Savage LS650)
is rated at 30 HP at 3000 rpm:
http://www.totalmotorcycle.com/photos/2002models/2002models-Suzuki-LS650Savag...Isn't 30hp low for a 650?
Cruiser riders like the mild mannered Savage, and its low gearing allows it
to out-accelerate
an 883 Sportster up to 50 mph.
But, you got the peak power RPM wrong, it's 5400 RPM, not 3000 RPM as you
wrote.
Horsepower production is based upon increasing the peak RPM the engine turns,
if volumetric efficiency (cylinder filling) does not improve. Simplistically,
if you want to extract 60
horsepower from the Savage engine, all you have to do is double the engine
RPM to 10800 RPM.
But, who ever heard of twisting a big single up that high? My counterbalanced
short stroke
KLR600 will rev up to around 8000 RPM, but piston rocking of the 100mm piston
causes it to use
a quart of oil every 500 miles.
The Savage is counterbalanced too, but it's a square engine (i.e., the bore
and stroke are the same).
Bore and Stroke: 94.0 mm x 94.0 mm (3.7 in X 3.7 in)
Power and torque output: 30 hp @ 5400 rpm, 33.5 foot pounds @3400 rpm.
Horsepower = Torque X RPM divided by 5252. If the engine still makes 33.5
foot pounds of torque at 5400 RPM, it makes 34.4 horsepower.
Piston speed at 5400 rpm = 0.166 X 3.7 X 5400 = 3317 feet per minute
It would probably be safe to operate the Savage engine at 7400 RPM
where it would produce 47 horsepower.
The piston speed would be 4545 feet per minute.
This would be a relatively safe piston speed to avoid ring flutter, but the
mechanical stress on the moving parts would almost double.
Stress = ( 7400/5400 ) squared = 1.88
There is probably somebody out there in AMA Short Track land who loves Savage
engines and has a high compression, re-cammed Savage engine in a custom flat
track frame.
I don't think a cruiser rider would want to go so far, but 47 horsepower in a
350 pound cruiser sounds like it's quite adequate. It would be loud, with a
megaphone exhaust and open air intake and re-jetted carburetor and the rider
would have to keep the engine in the right gear all the time.
Finding different pulleys and a longer drive belt to re-gear a souped up
Savage might be difficult.
This is how you can experimentally determine how the horsepower delivery of
the Savage engine would
feel, without buying an aftermarket camshaft.
http://www.bikebandit.com/partsbandit/showschematic.asp?dept_id=2412069Turnthe engine to TDC on the compression stroke. Remove the camshaft. Slot
the bolt holes in item #2 sprocket, reinstall the sprocket and cams with the
bolts loose and rotate the crankshaft about 5 or 6 degrees without allowing
the camshaft to turn. Then apply Loctite to the bolts one at a time and
tighten them.
This camshaft degreeing will retard the power peak until a higher RPM and
increase peak power at the expense of low end torque.
Actually the best cheap change is move the clip to three, drill out a brass plug
and adjust the low end needle. 8^) Slap on a suppertrapp exhaust (wish there was
a better header) don't forget the turbo (it's been done and works well) ditch
the belt and us the gears off a GS750. Bigger carbs can be done but the mileage
goes somewhere south of BAD. Best change is to get a bigger fuel tank, 108 miles
and you either coast into a gas station or start walking.
I had one, I blew it up...I need a motor.
--
Keith Schiffner
Assistant to the Assistant Undersecretary of the Ministry of Silly Walks.
"terrorist organization" is a redundancy
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