Cam Timing

discussions specific to the 906 Paso
User avatar
Duc906
Posts: 269
Joined: Mon Mar 30, 2009 7:59 pm
model: 906 Paso
year: 1989
Location: Australia

Re: Cam Timing

Post by Duc906 »

romus
It's great to here you got the job done. :thumbup: I appreciate your feedback and kind words. I rode with the cams at 106 deg for a few weeks and I was happy with how the bike was running and, like you, I found the bike was great around town. It also performed well on the open road,160kmh was what I took it up to and it felt smooth all the way, no sign of pinging. I changed the timing to 110 deg a couple of weeks ago. So far the only noticeable difference is at the higher end rpm, above 6500rpm. The weather is starting to turn colder so the desire to go for rides is fading.I want to try the timing at 114 deg before winter gets here, but I would be happy to set it back at 106 deg,to be cont.........
User avatar
higgy
paso grand pooh-bah
Posts: 3263
Joined: Tue Jul 29, 2008 9:50 pm
model: 906 Paso
year: 1990
Location: Hilltown,Pennsylvania
Contact:

Re: Cam Timing

Post by higgy »

No noticeable difference to air fuel mixture (AFM). I have a gauge showing AFM as I ride and it seems to be reading the same, but I need more driving to be sure.
Hey Warwick,out of curiosity have you tried to adjust your air mixture screws since doing your cams. Wondering if you still have the difference as before or if they can be adjusted in a more balanced fashion ?
Higgy
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
higgy
paso grand pooh-bah
Posts: 3263
Joined: Tue Jul 29, 2008 9:50 pm
model: 906 Paso
year: 1990
Location: Hilltown,Pennsylvania
Contact:

Re: Cam Timing

Post by higgy »

Ken
Your impressions on the different cam timings would make a nice addition to your Timing doc :thumbup:
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
romus
Posts: 135
Joined: Wed Mar 25, 2009 12:06 pm
model: 906 Paso
year: 1990
Location: Brisbane, Australia

Re: Cam Timing

Post by romus »

higgy wrote:
No noticeable difference to air fuel mixture (AFM)...
Hey Warwick,out of curiosity have you tried to adjust your air mixture screws since doing your cams. Wondering if you still have the difference as before or if they can be adjusted in a more balanced fashion ?
Higgy
Yes, I am almost the same adjustment for both air mixture screws, now that the cams are timed together. Just a 1/4 more turn for the rear cylinder to account for the bend in the rear manifold.
Warwick - on a learning curve and on a
Ducati Paso - Soul of a thoroughbred :P
User avatar
paso750
paso grand pooh-bah
Posts: 5505
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Cam Timing

Post by paso750 »

Hi,

a friend of mine is prepairing to optimize his ignition. He would like to correct the ignition timing of the rear cylinder also to improve the engine`s smoothness (which is only possible with some modification). Appearently the ignition timing of the rear cylinder is by 2° less advanced than the front cylinder to reduce thermal load. The pick up bracket seems to indicate this, too. The strange thing is that noone, incl. some Ducati mechanics seem to know about this.
Anyone out there know something ?
Image

G.
User avatar
higgy
paso grand pooh-bah
Posts: 3263
Joined: Tue Jul 29, 2008 9:50 pm
model: 906 Paso
year: 1990
Location: Hilltown,Pennsylvania
Contact:

Re: Cam Timing

Post by higgy »

Hey G
Seems to me I remember an article at a tech site about fixing this. I'll take a look tonight to see if I can find it again :thumbup:
If I remember it was an Italian site with a guy using the modified Two plug heads in his cart
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
paso750
paso grand pooh-bah
Posts: 5505
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Cam Timing

Post by paso750 »

higgy, if you find it let me know :thumbup:
User avatar
higgy
paso grand pooh-bah
Posts: 3263
Joined: Tue Jul 29, 2008 9:50 pm
model: 906 Paso
year: 1990
Location: Hilltown,Pennsylvania
Contact:

Re: Cam Timing

Post by higgy »

Still looking G :banghead:
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
romus
Posts: 135
Joined: Wed Mar 25, 2009 12:06 pm
model: 906 Paso
year: 1990
Location: Brisbane, Australia

Re: Ignition Timing

Post by romus »

higgy wrote:Still looking G :banghead:
This is an interesting question. I was wondering about ignition timing.

So far I have done the good improvements on the carb and cam timing. I understand that ignition timing is one of the other factors that should be adjusted right.

What is this thermal load anyway, that they would want to fix it by retard ignition timing for the rear cylinder? Why would it be a mistake to be fixed?
Warwick - on a learning curve and on a
Ducati Paso - Soul of a thoroughbred :P
duc907
Posts: 83
Joined: Sat Aug 18, 2007 12:00 am
model: 907 I.E.
year: 1992
Location: Cleveland O.

Re: Ignition Timing

Post by duc907 »

romus wrote:
higgy wrote:Still looking G :banghead:
This is an interesting question. I was wondering about ignition timing.

So far I have done the good improvements on the carb and cam timing. I understand that ignition timing is one of the other factors that should be adjusted right.

What is this thermal load anyway, that they would want to fix it by retard ignition timing for the rear cylinder? Why would it be a mistake to be fixed?
I have only heard of this being done on air cooled vee twins that do not get enough air over the rear cylinder to cool it. Is there some one out there with more info?
User avatar
paso750
paso grand pooh-bah
Posts: 5505
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Cam Timing

Post by paso750 »

It`s not a mistake that has to be fixed. The engine should run smoother when removing this though. The question is how much thermal load will change.
Some random thoughts: if the timing is not set correctly the rear cylinder may be more than 2° off. Causing the engine to run rough. Some guys report that the engine runs better when the carbs are not perfectly synchronized but adjusted slightly towards the rear cylinder.
A friend measured the degree marks on the flywheel and they are accurate. Hence due to one pickup being 2° off the marks on pick-ups and flywheel don`t perfectly match. Only one mark can. So how do shops adjust the pick up (bracket) ? Considering that noone asked knew about this they probably set the pickup bracket to the "middle" meaning they try to match front and rear marks which in the end causes both cylinders to be more off correct timing.
Btw anyone used a TDC finder to precisely measure if the TDC marks are accurate ?

G.
User avatar
higgy
paso grand pooh-bah
Posts: 3263
Joined: Tue Jul 29, 2008 9:50 pm
model: 906 Paso
year: 1990
Location: Hilltown,Pennsylvania
Contact:

Re: Cam Timing

Post by higgy »

Btw anyone used a TDC finder to precisely measure if the TDC marks are accurate ?
I still have my old two cycle dial indicator set .When I do finally get around to doing my cam timing I'll let you know what I find
Was planning to work on the bikes today,wife had other ideas :banghead:
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
Tamburinifan
paso grand pooh-bah
Posts: 1501
Joined: Thu Jun 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Gothenburg, SWEDEN

Re: Cam Timing

Post by Tamburinifan »

Btw anyone used a TDC finder to precisely measure if the TDC marks are accurate ?
Engineer friend did this on a DB2. TDC mark was just 1-2 degrees off.
Gert

907 I.E. -91
M900 -97
MTS 1100s -07
User avatar
paso750
paso grand pooh-bah
Posts: 5505
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Cam Timing

Post by paso750 »

It`s mentioned in the file:
BE VERY,VERY GENTLE WHEN ROTATING THE ENGINE WITH THE
PISTON STOP IN AS YOU DON'T WANT TO PUT THE STOP THROUGH
THE TOP OF THE PISTON.ALSO, DO NOT ROTATE THE CRANK A FULL
360 DEGREES WITH THE STOP IN AS THERE IS A CHANCE THAT THE
VALVES MAY MAKE CONTACT WITH THE STOP.
This is specially the case if larger valves are installed or cams with increased lift or like in my case both.
Attachments
DSCF2138.JPG
DSCF2138.JPG (121.57 KiB) Viewed 12183 times
DSCF2139.JPG
DSCF2139.JPG (126.07 KiB) Viewed 12183 times
User avatar
paso750
paso grand pooh-bah
Posts: 5505
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Cam Timing

Post by paso750 »

A couple of years ago I tried to learn more about cam & valve timings and collected lots of info from numerous sources. I meshed up many texts into one file. Most sources were in english so the file is, too. At a certain point or depth of an engine topic most sources begin with mathematical formulas. Tbh since that is when I begin to lose interest :roll: there isn't any of that. It was intended as a sort of work of reference for myself while trying to keep things understandable. If somebody is interested, here it is:
https://app.box.com/s/pst9p706lhf9nvrf8kzpm6kcr5zefayb

G.
Post Reply