cams dialed in

marvin

I finally borrowed some time from what i should be doing to degree my S4RS cams today. 108/107 centerline (S cams). The adjustable pulleys sure make it easier!

I have decided after seeing several dyno charts for other S4RS engines (139 HP) that I should weld in the corse frame gussets. A bit of a bummer now as my frame has been painted for quite some time. While I'm at it I will cut off the helmet lock bracket, trim the fork stops (for corse style yokes), and weld in a fitment for the steering damper on the left side. I have ordered some 2" stainless pre-bends to make an exhaust. Finally getting back to it!!

griff851

Quite a weapon your tinkering with there Marvin. Going for the full effect and getting engine life. Nice one.

Griff

Mr.R

Good idea about the gussets etc on your frame, shame it's already been painted though.

When I get around to having my frame painted (or I may well go for powder coating) as it's getting quite tatty now, I was going to carry out those mods, also lopping off the odd bracket that's no longer in use, (I've junked the under seat header tank) drilling a few lightening holes and possibly converting the stiffening tube that runs through the airbox to the removable style.

More for the pose value really, that and the fact that I can take the frame into work and weld it up, we've got Mig,Tig,Gas,Arc kit it's nice to be spoiled for choice and the Boss lets me use it after hours FOC.

I'm hoping to hit close to the 130 rwbhp mark with my longstroke 984 motor.
After some recent discussions with Chris Steedman, he thinks that sort of power is well on the cards using my 916SP heads, which I've already had 35/31 valves fitted to and a little of his 'Magic' in the ports/combustion chambers.
I'd supplied him with the Valve sizes, cam timing/lift etc and he came back with some ideas about sizes at the splitter etc, funny thing was that the standard apart from the valve sizes heads match Chris's suggestions at the splitter to the 'T' as in spot on!
Another well respected cylinderhead man Pete Willis a guru/God in the competition car tuning world reckoned that the port sizes were better suited to 37mm inlet valves, but Chris's the Ducati specialist with a track record in extracting good/outstanding power from the Desmoquatro heads.

Steve R

spike

can anyone give me the spec for the extra gussets / bits removed etc , also has anyone got piks of the alteration on the top brace ? i remember seeing it done it involved 4 identical slugs i think 2 in the frame and 2 in the shortened top brace with the joint half and half if you get what i mean ?? i,ve got the drawings for the alterations that were done on the bot bikes a few brackets off and a few on for the modules down near the battery but i,m now looking at altering a frame to the best spec but still with some " historical " relavance

spike

WolfManSpecial

i have doit something similar tho the chassis of my bike el mojito

sp2 boy

I went to a friends workshop to repair some elongated holes on the spare frame and it seems that it has had a knock at some point! 😯

Looks like it is on the back burner again...for a while.

spike

hmmmmmm !!

Henrik

marvin wroteI finally borrowed some time from what i should be doing to degree my S4RS cams today. 108/107 centerline (S cams). The adjustable pulleys sure make it easier! I have decided after seeing several dyno charts for other S4RS engines (139 HP) that I should weld in the corse frame gussets. A bit of a bummer now as my frame has been painted for quite some time. While I'm at it I will cut off the helmet lock bracket, trim the fork stops (for corse style yokes), and weld in a fitment for the steering damper on the left side. I have ordered some 2" stainless pre-bends to make an exhaust. Finally getting back to it!!

How do you dial in the cams?
This was probably a real stupid question, but if you reach 139 BHP I have to do something😁
Pictures and a "Cam timing for dummies" would be appreciated.

Good to know you picked up your project again. Mine has been used on 20 track days so far this year and has been 100% reliable, even though I let her down at one occation🙁 Engine has not been opened and the fairing only goes off for changing oil, which also means that she is really dirty now.

Brgds
Henrik

marvin

Hi Henrik,
It's difficult to explain in a short paragraph but essentially you mount a dial indicator to see when your valves open and close, rotate the cams to have them open/close where wanted. On your engine you have adjustable pulleys. Without adjustable pulleys you have to use offset keys.
Brad has great information about cam timing on his site.
http://www.bikeboy.org/camtime4v.html
I set mine at 108/107 as per his advice. (intakes advanced 4 degrees, exhausts retarded 4 degrees)
If you do a search on the internet there is quite a bit of information on "How To".

marvin

marvin

Henrik,

Here's a link to cam timing on a 2V. 4V is basically the same. Use .040" or 1mm lift though, not .030"

http://www.ducatitech.com/2v/maint/rebuild/headwork.html

Marvin