Mike , why are you even using rear brake?
That’s only fir off track excursions from brain farts!
Sorry couldn’t help myself.
Good luck with your search for a reason why it’s happening.
Paul

I hardly touched it Paul. First session. I am baffled. I got thru the second day tech by telling them the three ZIP ties holding up the brake pedal were there to stop me from using the rear brake —- and they passed me.

The rotor was supposed to be SS, and I have decided it is Cast Iron. The pad was sintered, and really grabbed it hard. Still, the bracket should not be that feeble. I will fix it.

MikeV

PS: I think Marco said “I use it because it is there”. For me it is just kind of a comfort thing, a “dead man’s” pedal. Warm and fuzzy.

Hi Mike,
I am curious why you mounted the Dyna mounting plate on top of one supplied with the Superpantah cover. I think the one he supplies will accept the ignition pickups directly. Was it for easier adjustability?

Thanks
John

Beautiful bike.

Yes, I think that is why I did that. If the two pickups were screwed to the spots on the small aluminum circular plate provided by SP then that timing would have to be accepted — whatever it is — 28, 30, or ? degrees. And, only one of the pickups has provision for any movement. Plus the cylinder timing separation might not be perfect, there could be a difference of a few degrees. By keeping the DYNA plate you can perfect the separation and both can be advanced or retarded at the same time. And I have done that a few times. You do have to grind off the ends of the tiny pickup screws so the plate will not warp when bolted on, and so adjustment is smooth.

PS: since the caliper trailing rod has been relocated with a plate to the engine and I installed non-sintered pads there have been no problems with the rear brake. Perfect!

MikeV

In another recent posting the issue of cams, and valves, and valve clearances resurfaced. I like to yank Cranky’s chain now and then, so….

Cranky was worried about the .022” clearance I used on these 900-spec heads, using P cams. And I admitted that was after using smaller valves (42.5 and 37.5mm) to get there. Just did not want to sink them more to get even stock 43 and 38mm valves in. Got 5.8mm of clearance at rest. Well, they never touched! No problem. But, the engine did not rev as high as I hoped either. Not satisfied.

So last winter I pulled the heads, because I was curious to see the results, and had begun to question why using the lower-than-900 (ss, st2, ie) lift cams of the P grind made any sense in the much taller combustion chamber of the 900 heads. The 900s all have 11.8mm or so intake lift, vs 11.2 for the P cams. And the st2 and ie cams have 11.4mm exhaust lift vs only 10.4 for the P. Yes, the P cams have more duration, but that is also what causes the valve clash! That is true of all the old-school long-duration race cams (Montjuich, NCR, Gio Ca Moto, FBF, ORSP, etc.). I thought maybe this bigger engine would just be happier with something else?

So, I have now installed two st2 horizontal cams (set at about 110 degrees lobe centers) and was able to increase the intake valves to 44mm. Left the exhaust valves alone. The valve-to-valve clearance on opening was so large I don’t remember caring, or even writing it down - but I probably did. The engine starts and idles better. Easier to live with. This Friday I will see if it runs better (more RPMs) at a track day.

PS: also going to try some 100LL Avgas for fun.

Later, MikeV

7/15: Well, it pulls strongly to 9250 now, but that is about it for acceleration. It seems that most of the 900 engines tap out at about 8500. Better than before, but not 10000. Will probably take some serious porting to achieve that.

I did not get to test the Avgas, so there may be a bit more as-is? Next time.

Finally, some "Proof it Run" photos. The Ridge, in July. All is well but for the very-high first gear ratio (2.0) that makes the downhill, bending-back, 15-MPH, turn 13 a matter of survival. Came back and added another tooth to the rear sprocket. Why do we need that kind of turn on a track? MikeV

Mike, great to hear you had a good time and that the bike works well.
Paul

I'm with Paul, glad you were able to enjoy the fruits of your labor. That's a special bike. Lou

Great stuff Mike, beautiful machine. Boucher.

Hello, Mike, I too have an idea that is nagging in my head right now.
You were talking about cam st2, but the st2 is an injection motorcycle, I believe that to make a naturally aspirated engine work, the distribution diagram must be very open, I have seen that an injection motorcycle, the injector opens the flow even at valve closed, and finding the red-hot valve head, a cloud of petrol vapor is created which in succession the airbox pushes into the combustion chamber.
The naturally aspirated engine must necessarily aspirate, otherwise the sprayer cannot do its job.
I believe that the P and ncr7 cams are the most performing, but I have seen that the first series monster 1993 cams, produced in small series, in my opinion would be very performing.
I had in mind to mount them on my Hyper 1100 carburettor engine that I do in hill climb competitions, but there is a bit of work to do.