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102 Posts
Thanks StraDuc, belter has already answered about the final belt tension.
My dubt was only for the tension to be set during cam dialing.
The 900 manual says to set it to 11 (on old ducati tensioner tool), check/set cam timing, and than bake off to 3.5. I know the 900 is a bit o.t.... i will re-check on the other vid.

The dubt about to use the exaust instead of intake valve to check cam timing is more on topic..

2,389 Posts
Discussion Starter #22
it's a matter of convention. how the first person does it sets the way everyone else does it sort of thing. the first time i did cam timing on a 2v was fitting some vee two cams to a 900ss, and vee two told me to do it at running belt tension, so that's what i did.

if you set the belts tight it is meant to simulate the engine growing when it gets hot, but that would have all dimensions growing evenly, and no net change to cam timing. when you over tighten the belts, it pulls the belt more in the clockwise direction between the crank pulley and the moving adjuster, which retards the cams. it makes about 2 degrees difference. i always do desmoquattro with the belts at 11 on the lowener tool, just because that's the convention and how i've always done it.

some people get really stressed about this, and i had one guy telling me it was all wrong because his cams on a 4v moved between 1.5 and 3 degrees and everyone's numbers, including mine, were rubbish. depends how carried away you want to get. you are more than welcome to start a new convention and gather followers. sounds a bit like religion now.

as for checking the exhaust cam - i never do on a single cam engine, as i'm more concerned about what the inlet is up to. if you're asking because access is easier, well, i'd still do the inlet. none of them are that hard.

102 Posts
Thank you Brad.
I found vertical centerline at 120.2 (orizontal 117)
I set both cylinder to about 115° with belt in running tension and zero valve clearance.
H op 23 cl 73
V op 24.5 cl 73.5

As indicated in the manual I've re-measured the angle rotating the crankshaft backwards.
H op 26 cl 71 ctl 112.5
V op 27 cl 72.5 ctl 112.7
I don't know if these last numbers make any sense....

The compression became 110psi on both cylinder (was 95v 105h) and the bike pulls stronger from low rpm

How do you usually set this (900ie) engine?

I was a bit scared about valve/piston clearance..The improvement advancing only 2/5° is quite impressive.

With all the tools unavaliable at the time, my procedure was a bit unconventional and of unknown (to me) accuracy:
Gently rotating the clutch with fingers instead of using rotating tool to find tdc (with piston stop).
Rotating rear wheel for opening /closing angle measurement.
To advance the timing:
-loose and than slightly tight pulley screws.
-Set crankshaft at tdc horizontal.
-Lock the pulley with a almost zero clearance pin (on the left)

-loose pulley screws.
-rotate the crankshaft backwards the required angle for correction.
-tight pulley screws.
-unlock the pulley and remeasure opening and closing clearance.
-repeat with different correction if necessary.

Also the damn dial gauge contact point was stuck, can't unscrew it:
Used something like this:
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