851 1990 Valves clearance spec

patrick

Hi
This is the first time i do the valve clearance with the "load/unload" method.
Could you put an eye on this valve clearance report ?
According the 851 manual (closing spec 0,05/0,08mm) i should set thighter 4 closing valve rockers:
H intake left 0,13mm
H exhaust left 0,10
V intake left and right 0,12 / 0,15

A 2000 ducati service paper gives 0,16/0,25 (intake) and 0,11/0,20 ( exhaust) for ST4, 748, 996 etc
Tending to think a too tight play is not recommanded for closing rockers at least for later models....

Set tighter? Leave as it is ? or set all bigger?
Many thanks for your advices
✌Patrick

hindsight

Hi Patrick - If it were me, I'd be taking your horizontal left closer (both intake and exhaust) down to as close to 0.05mm as possible, and both of your vertical intake closers also down to 0.05mm

Mr.R

I don't use the load/unload method, I just set the closers at 2 thou and the openers at "spot on" what they should be (depending on the cams) without out any give or take on the tolerances.
I've never had a rocker fail after setting them up this way...Using feel and then going down one size on the shim.
I set up Bevel singles and twins at NIL clearance on the closers, using feel to set them up and never going anywhere near a set of feeler gauges.
...and again haven't had any closing rocker failures in almost 40 years.

Steve R

griff851

Hi Patrick, the reason for the difference is there are 2 sets of tolerances. The build and running (for service technicians. The manuals usually have the build specs. The shops get these charts that have both. The wider running tolerances are supposed to help get service costs down.
The average rider would not be aware of the differance in performance as it will change the cam timing ever so slightly. But if your like most of the guys here and want everthing just right, then by all means take them back to build tolerance.
Just remember when checking with feeler gauges it is all about feel. Just dragging as you move the gauge is about right. Apply to much pressure on the closer can distort your reading. Using a dail gauge is the most accurate, but a lot of pissing around building plates and arms for the gauge. Also take the reading from the center of the lobe, then check it towards the ends of the lobe. Old bevel cams are shockers for having little risers on the end of the lobes, so you have to whip them out and grind the little fellers.

patrick

I am going to set the inlets first as closed as possible to 0,05 mm
Many thanks
Patrick