So in Jans case at Garelli , maybe the balance shafts added inertia was a case of the crank needing more inertia anyway.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Gordon Blair is Doc Fleck?
they are two people Robert Fleck and Gordon Blair, but they were both at QUB
https://www.researchgate.net/scienti...9_Robert_Fleck
https://www.researchgate.net/scienti...2926_G_P_Blair
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Kinky is using a feather. Perverted is using the whole chicken
[QUOTE=wobbly;1131137968]So in Jans case at Garelli , maybe the balance shafts added inertia was a case of the crank needing more inertia anyway.[/QUOTE
Some people were telling me I was crazy putting a balancer in a racing engine, as it would cost power....
6 years later Honda did it too.
And the others followed....
Around the year 2000 heavier crankshafts were tested successfully.
Aprilia did this on-track
[QUOTE=jamathi;1131137992]Hi Jan, I would have also thought it would allow you to use lighter engine casing and frame etc as it would need to be as strong to absorb the vibrations for a double benefit.
I remember an observation made decades before that on a MX bike with a World champ rider that it lapped the track faster with an effective silencer , not because it made more power, but the rider subconsciously backs off the throttle when its too loud.
I wonder if vibrations would have the same effect on the rider.
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Kinky is using a feather. Perverted is using the whole chicken
Once tested my Honda VF500 F2 without generator flywheel, to see how engine react to less inertia, with intention to put on smaller rotor later.
Immediately effects was very nice, the engine feels faster, riding through corners very light. Motorcycle became so lovely controllable with very nice on and off throttle feeling.
BUT………..some very terrible sound appear at 8000-9200 rpm interval. Its not vibration, but horrible metallic sound, like crank resonated with deformation without flywheel or something when torque rise up. It feels like engine broke down in minutes. From 9500 to 12000 all goes quite.
Then put on rotor again and bad sound disappear.
Pretty sure both the 400 and 500 camchain VF's were 180 degree cranks. But it's been a long while...
Katinas, I don't know what your noise was - but I built a VF500 to run in a speedway car without the alternator rotor. In fact, with that end of the crank cut off flush with the end main bearing. No problems with the lower end lasting. Only the idiot driver, unable to read traffic.
Husa, you are right, VF 400 500 is 360 crank.
VFR 400 750 is 180, the same configuration like on NSR 500 V 90 84-85-86, just 84 rotate backward.
Grumph, are you used original cdi or programmable, maybe without rotor, engine needed different ignition curve as piston velocity at TDC on compression phase slower than with flywheel. Maybe I need to play little with ignition timing, without rotor.
Used original ignition. TCI - transistor controlled ignition - not CDI. Run battery powered as total loss. No change to the curve or limiter. Went very well on quarter mile dirt ovals.
You may be right about the crank configuration - it was some time ago.
The rotor itself has no effect on the balance factor of the crank. The rotor is balanced as a separate unit. i've never seen a bike crank where the add-on rotor assists or alters the balance factor. On the other hand, it's quite common in cars. A lot of American V8's and V6's have flywheels with assymetric weights to bring the crank into balance.
It's very common to ditch the alternator rotor on big fourstrokes used for racing. There's invariably enough crank inertia that changing ignition curves to compensate isn't necessary.
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