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 Post subject: Cam Timing
PostPosted: Sat Jan 23, 2010 8:40 am 
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Joined: Mon Mar 30, 2009 7:59 pm
Posts: 256
Location: Australia
model: 906 Paso
year: 1989
I have written up detailed instructions that can be downloaded from Higgy's excellent web site here;
http://mysite.verizon.net/vze2hw9t/index.html
or look in the 750 magazine section
viewtopic.php?f=1&t=1551&start=0
Happy tuning :choo:



Over the last few days I've been checking the cam timing on my 906.
After triple checking my measurements this is what I came up with.

Horizontal Cylinder
Inlet: Open 24 deg BTDC
Close 68 deg ABDC
Lift 11.65mm(0.45866")

Exhaust: Open 59 deg BBDC
Close 32 deg ATDC
Lobe Center Angle: 112 deg

Vertical Cylinder
Inlet: Open 19 deg BTDC
Close 71.5 deg ABDC
Lift 11.44mm(0.45036")

Exhaust: Open 58 deg BBDC
Close 33 deg ATDC
Lobe Center Angle: 116 deg

The following is a work in progress,I welcome any input,pm me please.

I’m not a tuning guru by any standard, this is my first experience with cam timing and my knowledge is presently limited to working on my own 906 Paso so I’m going to concentrate on the procedure rather than the technical side. There are plenty of internet articles that cover the effects of advancing or retarding the cam timing. The Ducati factory specification for the 906 recommends a Lobe Centre Angle of 10 degrees. After discussing my findings with Brad at The bikeboy.org he recommended I advance my timing to 106 degrees on both cams. So far, what I have discovered is that by advancing the timing by 4 degrees increases the bottom end and mid-range power/torque but sacrifices some top end. My plan is to try some different settings so that I can get an idea myself what effect they have on performance. As for carrying out the job, it is not very difficult, just time consuming. There is no point in rushing it anyway, because the consequence of getting it wrong can be very costly. It took a couple of days to make up the tools and another day of setting up and taking and double checking measurements. Then there was the three days wait for the keys to arrive and....well you get the point.

Before I could do any measuring I made up some tools i.e.degree wheel, pointer, mount for dial indicator, piston stop, extension for dial.Alternatively you can buy them from parts suppliers.
ImageImageImageImage
The first step is to set the degree wheel to zero.
1. Remove both spark plugs.
2. Mount the degree wheel on the alternator end of the crank.
Image
3. Mount the pointer.
Image
4. Rotate the engine forward(anti-clockwise) and bring piston to the start of the compression
stroke.Do this by holding a finger on the plug hole and feeling for the pressure when the
piston starts to come up.
5. Screw in the piston stop and very,very gently rotate the engine until the piston
rests against the stop.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

6. Loosen the degree wheel and set it to 0 deg TDC,without moving the crank.
Image
7. Unscrew the stop and rotate the crank past TDC just enough to allow the stop to be
screwed back in.(My stop takes up 38 degrees of rotation so I rotate the crank about
50 degrees).Screw the stop back in and rotate the crank very,very gently in
reverse(clockwise) until the piston rests against the stop again.
8. Take note of the angle on the degree wheel.As mentioned earlier mine is 38 degrees.
Image
9. Now loosen the degree wheel and set it to half of the angle noted in step 8.eg.If the angle
noted was 38 degrees then you would set the degree wheel to 19 deg,again without
moving the crank.

Image
10. Unscrew the stop again and rotate the crank forward just enough to allow the stop to be
screwed back in, rotate the crank back gently until the piston touches the stop
again.Repeat until the degree wheel reads the same either side of 0.The wheel is now set
correctly.

The next step is to set up the dial indicator.

1. Remove the valve cover and screw the dial mount in it's place.
Image
The plunger on the dial should be almost all the way in when the valve is closed.
Ensure the piston is at TDC.
2. Set the indicator to zero.
3. Insert a feeler gauge to take up the valve clearance,mine was .01mm(.004").

Taking the measurements.

All measurements should be taken while rotating the engine forward only. If you happen to go past your mark and rotate the engine back you will get an incorrect reading due to gear lash. I found a difference of around 2 degrees when I measured mine. Also, it is a good idea to measure everything at least 3-4 times to make sure you get the same result, plus it makes for good practice.

1. Rotate the crank until the indicator reads 1mm.Take note of the angle on the degree
wheel,mine was 19 degrees BTDC.
Image
2. Continue to rotate the crank until the indicator reads 1mm before the valve closes.Take note
of the angle on the degree wheel,mine was 71.5 degrees ABDC.
Image
Now for some maths.The formula for working out the lobe center angle is thus:
1. Inlet opening (IO) + inlet closing (IC) + 180 = duration
2. Duration / 2 = half duration
3. Half duration – IO = Lobe Center Angle

So in my case for the vertical inlet:
1. 19 + 71.5 + 180 = 270.5
2. 270.5 / 2 = 135
3. 135 - 19 = 116
I went through the process of measuring all the lobes just for my own reference but because the inlet and exhaust lobes are part of the same cam on a 2 valve motor it is only necessary to measure the inlet lobes to check if the timing needs to be adjusted.


Last edited by Duc906 on Sun May 30, 2010 9:48 am, edited 9 times in total.

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 Post subject: Re: Cam Timing
PostPosted: Sat Jan 23, 2010 11:44 am 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3153
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
Try these guys
http://www.ca-cycleworks.com

First rate pictures and a decent explanation for nubes :thumbup: :thumbup: :thumbup:
Great job :cool:
Would you be interested in adding a section to our Weber mod doc? PM me your email addy I'l send you a preliminary copy

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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


Last edited by higgy on Tue Feb 09, 2010 1:40 am, edited 2 times in total.

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 Post subject: Re: Cam Timing
PostPosted: Mon Jan 25, 2010 12:01 pm 
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Joined: Mon Mar 30, 2009 7:59 pm
Posts: 256
Location: Australia
model: 906 Paso
year: 1989
Thanks Higgy,I've managed to source some here in Oz :thumbup: :beer:


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 Post subject: Re: Cam Timing
PostPosted: Mon Jan 25, 2010 1:27 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3153
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
Where for everyone's future reference

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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


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 Post subject: Re: Cam Timing
PostPosted: Fri Feb 05, 2010 9:42 am 
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Joined: Mon Mar 30, 2009 7:59 pm
Posts: 256
Location: Australia
model: 906 Paso
year: 1989
What a difference this has made, I have a new bike. After fitting the new offset keys the timing measures,
horizontal cylinder 106 deg l/c, vertical cylinder 106.5 deg. It idles and accelerates sooo much smoother now, doesn't shake
like a dog shit'n razors. It has stopped back firing every time I go to start it, which was embarrassing,and starts a lot easier.
I got the keys off Brad the bike boy.At $49 each I thought they were expensive for what they are but with the results I got I guess they were worth it,should have done it a long time ago but thought it was only a job for the pro's. It has been a very rewarding job and wasn't that hard to carry out.There is a lot of info on the net to help as well.Here is a couple of good sites that I found:
http://www.bikeboy.org/camtime2v.html
http://www.ducatitech.com/2v/maint/rebu ... dwork.html
http://www.ducati-upnorth.com/tech/camtiming.php


Last edited by Duc906 on Wed Mar 03, 2010 9:59 am, edited 1 time in total.

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 Post subject: Re: Cam Timing
PostPosted: Fri Feb 05, 2010 11:10 am 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3153
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
Pictures are always nice,Maybe they can save just one more Paso from the ebay parts bin :thumbup: :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


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 Post subject: Re: Cam Timing
PostPosted: Fri Feb 05, 2010 8:11 pm 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1556
Location: Newzealand
model: 906 Paso
year: 1990
Uuuuugh this I didnt need :dunno: :lol: I have enough on my plate without having to worry about my lobe centre angles, I mean , its out there in the shed , where I cant really get at it , and now I find out that it may have a genetic illness, and the fact that it may go better ( maybe there is nothing wrong with the webber after all :P :P ha ha , mental image ,a bewildered looking Higgy, up to his arm pits in emultion tubes and venturies with Duc906 showing him a pair of ofset keys, raoflmao :lol: :lol sorry Higgy ) Can we get vernier pullies ( see what youve done :P ) or adjustable ones ?

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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 1:37 am 
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paso grand pooh-bah
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Joined: Mon Jul 19, 2004 12:00 am
Posts: 1714
Location: Hudson Valley, NY
model: 750 Paso
year: 1988
Adjustable one's show up on fleabay once in a while.

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'88 750 Paso * '87 750F1
'04 Multi 1080s * '88 650 Indy
'65 250 Monza - Moto Giro Project

Click HERE--> 750 Paso Tech FAQ
www.desmoducati.org
www.ducatisuite.com


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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 9:26 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5087
Location: southern Germany
model: 750 Paso
year: 1987
if you`re referring to adjustible cam belt pulleys note that these are not for the Pasos square tooth belts but for the later round tooth belts meaning that you have to change the lower pulley, too. I had that done on my P750.

G.


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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 9:34 am 
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Posts: 3024
Location: Finland
From what modell are your pulleys coming from? ...and what belts You use? :smoke:

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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 2:33 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5087
Location: southern Germany
model: 750 Paso
year: 1987
who, me ?!
The cam belt pulleys are aftermarket. From DSM as far as I remember and the belts and lower pulley are from a newer SS/Monster. Sorry didn`t write down any part numbers.
Image
Image


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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 4:40 pm 
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paso grand pooh-bah
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Posts: 3024
Location: Finland
Yes, i mean You. Thanks for intresting info. :thumbup:

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KTM 990 Adventure -08 metal dark grey
Paso 750 -89 red/metal grey
Paso 907IE -91 red/metal grey
Paso 907IE -91 red
ST4S -02 red/metal grey
ST2 -01 red/metal grey
Volvo V70 Bi-Fuel Classic/titanium grey


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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 8:55 pm 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1556
Location: Newzealand
model: 906 Paso
year: 1990
Both my SS motor and the paso ( I had to go look ) have round tooth pulleys ( phew ) which is good coz all my spare belts are round ones and if the paso was square that would mean I had been fitting round belts to a square pulley , surely you would notice something like that ( he says ... not all that confidently ). I bet my timing is a mile out on the rear pot as when I got the bike it had an interesting rattle at idle which turned out to be a loose cam pulley on the rear pot .Ashamed to admit but I just tightened it up, the key probly looked very second hand :oops:

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 Post subject: Re: Cam Timing
PostPosted: Sat Feb 06, 2010 10:40 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5087
Location: southern Germany
model: 750 Paso
year: 1987
that`s interesting. I didn`t think that a 906 would use a different belt type than the 750 except to a different length.


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 Post subject: Re: Cam Timing
PostPosted: Mon Feb 08, 2010 9:57 am 
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Joined: Mon Mar 30, 2009 7:59 pm
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Location: Australia
model: 906 Paso
year: 1989
Adjustable pulleys would be nice and I wouldn't have to keep buying different keys every time I wanted to change the timing.But because this was my first go at timing the cams and to keep it simple I chose the offset keys. :beer:


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