ESE's works engine tuner

[katinas]

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.

Thanks, of course its TCI.
With or without rotor there is no vibrations on this engine, but just very bad sound from 8000 to 9200 rpm. without rotor.

Just remember, the first year with Moto2 CBR 600 engines, they had some broken con rods bolts, just because without heavy electric starter, engine vibration character changed. Later it was dissolved with new bolts construction or shape.

[guyhockley]

Yep - if we employ two balance shafts per crankshaft, or the Husaberg-solution with balance weights on the crankshaft.
In our usual layouts there is a definite distance between crankshaft and balance shaft. This distance between a crank force acting in one direction and a balance force acting in the opposite direction causes a fore-aft rocking torque.
The balance shaft solution as used in the Aprilia RSA for example, with outrigger balance masses, allows the smallest distance between crankshaft and balance shaft center lines.
In the Husaberg approach this distance is zero, which in itself is perfect. But if you want to do this right, you'll need balance discs on both sides of the crankshaft and both these discs must rotate counter-crankshaft-wise, which will require a handful of gears.
Attachment 342597 Attachment 342598

I heard from a team that road-raced a Husaberg that the balancer bearing was a constant source of trouble. Presumably due to it effectively running at twice engine speed.

[guyhockley]

Interesting that this picture shows the 2 "right" ways to balance a tandem twin, 360 with counter-rotating cranks and 180 with both going the same way, yet the first KR250s reportedly were sent to Europe with counter rotating cranks at 180 and lots of vibration!

[Grumph]

Interesting that this picture shows the 2 "right" ways to balance a tandem twin, 360 with counter-rotating cranks and 180 with both going the same way, yet the first KR250s reportedly were sent to Europe with counter rotating cranks at 180 and lots of vibration!

And the road versions are also 180 deg phasing. Elsewhere on this site, there's a guy asking for help with a tuned road one. i've told him to get in touch with someone local to him who I know rephases them.

[husaberg]

I heard from a team that road-raced a Husaberg that the balancer bearing was a constant source of trouble. Presumably due to it effectively running at twice engine speed.

Husaberg balancer's got heavier in later years but they never installed a wider 2 row bearing until 2006
The Little ones had no issues with the bearing afaik, only the bigger ones. but the oe bearing is exceedingly expensive.
but You can surface grind a wider bearing to fit.

The earlier 2005 ones have to have bearings machined to fit as OE ones are not available but you can get a double row custom narrowed to fit.

PS why would the balancer bearing be running 2x crank speed?
it just runs in the opposite direction doesn't it?

[lodgernz]

PS why would the balancer bearing be running 2x crank speed?
it just runs in the opposite direction doesn't it?

Inside race running forward at crank revs, outer race running backward at crank revs. Balls would be stationary wouldn't they?

[husaberg]

You remember better than i did.
Def a 180 degree.
Attachment 342633

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.

okay i had a duff picture it seems VF400


https://www.ebay.ie/itm/380757154367

---

NC30

---

but NC24

[Frits Overmars]

why would the balancer bearing be running 2x crank speed? it just runs in the opposite direction doesn't it?

Inside race running forward at crank revs, outer race running backward at crank revs. Balls would be stationary wouldn't they?

They wouldn't. The inside and outside races rotate at equal, but opposite speeds, right. But as their diameters are different, so are their circumferential velocities.
The circumferential speed of the balls' outsides equals the circ.speed of the outer race, and the circ.speed of the balls' insides equals that of the inner race, which is lower. So the balls and their cage 'slowly' move in the direction of rotation of the outer race.

[guyhockley]

Wa-a-ay back someone who was building a replica, I think, was looking for Clisby information. Don't think it adds anything much but just found this.

[katinas]

Husa, thanks for correction, very interesting, on third generation VFR 400 NC30, they return to VF 500 360 crank configuration and RVF 750 RC45 too

The third generation of VFR400R was the best known version, the VFR400R NC30. This model saw the introduction of the 360° crank firing engine, which is also known as the "big bang" engine. The tachometer red-line was also raised to 14500 rpm.

[speedpro]

They wouldn't. The inside and outside races rotate at equal, but opposite speeds, right. But as their diameters are different, so are their circumferential velocities.
The circumferential speed of the balls' outsides equals the circ.speed of the outer race, and the circ.speed of the balls' insides equals that of the inner race, which is lower. So the balls and their cage 'slowly' move in the direction of rotation of the outer race.

If you assign + and - values to the directions of the crank and balancer to denote direction of travel you get +1 and -1. The difference is 2 which as far as the bearing is concerned, being between the two rotating objects, is the speed of rotation. That is 2X the speed of one of them

[JanBros]

re-read what Frits wrote again, carefully. you are only looking at it from an rpm point of view, but that is not the true speed of the ball's. the ball's speeds depends on their speed vs the speed of their contact patch.

it's the same as both wheels ont the same axle in a car when going through a corner : let's say the car goes through a corner at 50km/h, measured at it's CoG. the inner wheel has to travel a smaller radius than the CoG and the outer wheel a bigger radius than the CoG. Automaticaly this means that the outer wheel is rotating faster (maybe 53km/h) than the inner wheel (maybe 47km/h, the difference depends on the radius of the corner) as it has to cover more distance in the same time to make the corner.

[lodgernz]

They wouldn't. The inside and outside races rotate at equal, but opposite speeds, right. But as their diameters are different, so are their circumferential velocities.
The circumferential speed of the balls' outsides equals the circ.speed of the outer race, and the circ.speed of the balls' insides equals that of the inner race, which is lower. So the balls and their cage 'slowly' move in the direction of rotation of the outer race.

True. However, each ball, although hardly moving geographically, will be rotating at twice the revs it would in a normal single-direction bearing arrangement with one race fixed and the other rotating.
Maybe that's what killed them?

[Grumph]

True. However, each ball, although hardly moving geographically, will be rotating at twice the revs it would in a normal single-direction bearing arrangement with one race fixed and the other rotating.
Maybe that's what killed them?

I'd suspect that what kills them is lubrication failure - balls against cage.

[flyonly]

How did Aprilia turn the rotary valve on their engine? The rotary valve that is replacing the normal reed inlet.

I have seen a picture of an engine which is driven by belts off the clutch but wasnt sure if it was an Aprilia or not