The International CBX Owners Association

The V12. The rear set of cylinders have been turned around backwards to get the intakes in the center. Andreas flipped the cams from side to side incase the ramps on the cams were not the same slope in the opening and closing side. He made two ea tdc marks on the crank, one for each bank of cylinders. Assembled everything and started to turn over the engine. The intake was opening when the piston was traveling up, not down. Oop's. Who can tell me what was happening? I had to sit down in a quiet place, get out a pencil and paper, and figure out what the problem was. And a question for the CBX Technical Guru's is-Are the slopes on the cam ramps identical for the opening and closing side? If they are it will be easier to prepare another set of cams. Another problem-When you look down through the middle of the cylinder at the chains where they cross, they look much closer then when the engine was dis-assembled. I'm going to take a pic with my camera and blow it up. Should get a clear view how close they are that way. At one time Andreas made a shield to go between them but figured he had enough clearance so he dis-carded it. He might construct another.

I get a headache just thinking about what to do with the cams and how to correct the problem.

cbxtacy wrote:Assembled everything and started to turn over the engine. The cam chain is running through the head BACKWARDS. Oop's. Who can tell me what was happening?

You're getting ready to do a number on the cam chain tensioner on the back cylinders?

And re-time the cams. The intake is open on an exhaust stroke and the exhaust is open on an intake stroke. It probably would not run too strong that way.

I wouldn't worry too much about the quieting ramps George but the cams asymmetry may be an issue. The desire to open a valve quickly maybe incorporated in the leading ramp... Reversing the cam direction may require a regrind..
The only way to check would be with a dial test indicator & a degree wheel & do a plot.

Unless I am thinking on the wrong track here, if you turn the block and head around 180 deg. and run it off the same crank it HAS to turn backwards. The only way the cams will work right is to reverse the head or do the impossible and have an idler gear to change direction of the cam chain and I don`t think there is enough room in a CBX motor to do this.

As I picture it, the cam chain is running in the proper direction, but the head is turned around, so of courde it would be wrong. You will need to reverse the travel of the cam drive, something very diffigult with a chain drive. Gears, however offer possibilities........
Obviously, this motor is not intended to run for very long at any time. Air cooled motors don't like to have the exhaust side of the head out of the airstream. The CBX is marginal for cooling anyway, and hiding the ports from the air flow would be disastrous if run for any length of time.
That said, I admire the engineering that's gone into this project.

It is very unlikely that the opening profile is the same as the closing profile. Cams are usually not designed that way. As Larry said, the objective is to open quickly with a steep raise and towards the end of closing, the descend is slowed down to ease the valve on the seat.

cbxtacy wrote:And re-time the cams. The intake is open on an exhaust stroke and the exhaust is open on an intake stroke. It probably would not run too strong that way.

I don't quite understand this statement. The pistons don't know what they are supposed to do unless they are "told" by the timing, i.e.: the valves and the ignition. The intake and exhaust strokes are made such by opening/closing the valves and the spark. So, if the cams define exhaust and intake, just change the iginition

It hit me last night. Time the cam's at bottom dead center. Flipping them from side to side gets them turning the correct way but they're 180 out on the crank. I think. With the cams flipped the #1 becomes the #6. And flipping them would put the lobe away from the spark plug hole.

"Cheapest " way would be th incorporate reversing gears in the camchain tunnel. Two equal sized meshing gears with sprockets attached, the gears would need to be of larger diameter than the outer chain radius to prevent interferance. They could be quite slim as the cam/spring operation is balanced.

Benefits...
Exactly the same head/cam configuration as stock.
No need for the rear slipper tensioner as you will now have two main drive chains which are much shorter.
Plenty of lube cascading down the cam chain tunnel....

I believe they need to be installed at bdc with the #1 rear cylinder (#6 on a normal engine) away from the spark plug.

The cams are turning the correct way, Andreas flipped them years ago. Cam timing is off when turning the engine over. Intake was open during a piston stroke when the piston was going up. Not supposed to do that. And exhaust open when the piston was going down. Oop's.

And Andreas is playing with his degree wheel and dial test indicator this morning Larry.

George, I commend your enlightenment but if you reverse the head & switch cams left to right, they are still going the wrong direction. Or am I missing something here...

cbxtacy wrote:And Andreas is playing with his degree wheel and dial test indicator this morning Larry.

George, Looking at the data in the workshop manual, the cam lobes are not symetrical...
What alerts me is they quote lift of 1mm at degree of opening & not on closing. IE the transition point is impossible to measure with any degree of accuracy on the lift side...