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Adjustable Cam Timing Pulleys for S4, ST4, ST4s, S4R, 748, 916, 996 Desmoquatros

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VinceS:
Refer to http://hunterdog.org.au/DiscussionBoard/index.php?topic=814.msg2628#msg2628 for related info

VinceS:
I was just doing a major service and had to chuckle when I came across the old pics for this. As it turned out that particular bike got splatted before the pulleys got fitted - there is a story about a certain Commodore somewhere else here. Oops. So I still have the pulleys.

Whilst all the lightening pulley stuff is fine when it comes down to it you need to know EXACTLY where your cam timing is at and there is no way a rough and ready style solution (as mentioned earlier) would work. The attached pics show what I actually used, which is still a bit of an ad-hoc way to do it, but a little practice and you figure how to set it up to have the dial indicator resting on the closer properly through the entire stroke so you get repeatable results. Edit: The key is to get the dial indicator body in the same line as the valve, ie it MUST run parallel so that the foot of the measuring tip stays in the same relative place and doesn't either fall off or move and put a force on the dial indicator which WILL result in a false reading. Whilst making sure you take good care here, you also need to spin the engine a few times and get the same reading EVERY TIME or it doesn't count and you would be making adjustments / decisions based on at least a level of bs! Make the exact contact point of the tip very pointy then at least if it moves a small amount (without touching the adjacent surfaces) due to a slight out-of-parallel this will minimise sliding friction and hence bending stresses on the dial indicator and you will get repeatable results. Whilst it is not shown in the pics I bent the foot into a V shape and tilted it down a little more to ensure full repeatability.

The thing is the clearances MATTER. Cam timing is at 1.0mm lift so that means you stop turning the engine when the dial indicator shows 1.0mm minus the actual clearance on the actual valve you have it on. So if this clearance is 0.1mm then cam timing is at 0.9mm from the rest position. Similarly lift is what you measure PLUS the clearance. You need to get exactly the same numbers a few times in a row to know you have it sussed, and the trick is all about getting the dial indicator so it is pretty close (OK exactly) in a parallel line to the line of movement of the valve.

The pics below show the basic set-up I used, but in the final analysis of getting it exactly right I actually added a wooden wedge under the bolted on angle (Edit: Pic added) as it allowed me to fine tune the exact angle the dial indicator was at plus it improved the rigidity. The funny thing is I ran out of time and didn't fit the pulleys so still have them! But now at least I know exactly what the cam timing and lift is. Bit all over the shop really, but I will come back and play with this another day. Anyway it would seem from this that my inlet cams are worn, I need to do some more research there. Edit: Actually, when I was filing stuff I realised that really they aren't worn (much) but (mostly) just needed adjusting! This was momentary confusion about BTDC / ABDC. I had thought "oh, opening too soon, shutting too late = worn" but that is bs. Take the vertical one: at 14 deg BTDC it is opening 3 degrees earlier than the required 11 degrees, and at 55 degrees ABDC it is closing 6 degrees earlier than the required 61 degrees. So the correct action would have been to retard the timing about 4 degrees, which I didn't attempt, through ignorance! it is a borderline case anyway as I know from experience to get within +/-1 of target is no small achievement, but it could be a bit better than it is I reckon. The "research" bit is valid as I know seasoned players do vary timing a little from factory and this could be desirable, or not - I wouldn't know! But the bike runs beautifully as it is so who cares....

The hose by the way is connected to an air line - it is a reliable way to make sure the valves don't fall out, plus it is a very quick way to set the degree wheel up exactly (which yep I discovered after doing the turn against a stop and reverse then split the difference system. But when you stick 120psi of air in there it locks dead solid at 180 degrees from TDC). Of course you may wonder why the cams are missing in the below pics? That is because these were the tool developmental pics since at this stage I knew the magnetic base system was bs, and wanted to make up something that would work for all valve positions. I think the vice grips are going to stay (they are the auto-locking kind) as I had originally hoped to drill holes and bolt the top plate to the lower. However every valve seemed to need a slightly different position, plus the exhaust valves are about 3mm higher so I was clamping a packer between the angles rather than disrupt the dial indicator. each to his own I guess, but this ultimately worked very well and had that alluring property of being extremely cheap!!!

VinceS:
I have picked up all the bits for this job now. They had to come from Italy and came in last week. Pricing (including the HunterDOG current membership 10% discount at Frasers) is as follows, using the text in the first post:

 4 pulley inner flanges (part #16010761A), $61.13 EACH = $244.52

4 special pulley washers (part #85211241A), $2.70 EACH = $10.80

 a dozen 5x14mm allen head bolts and 4 pulleys. The bolts are part #77150402B but I am just going to get these from a local bolt supplier. NOT DONE YET

The pulleys you could get the stock ones (part #25510141A) BUT I DIDN?T. HOWEVER, HAD I BOUGHT THE STOCK PULLEYS I WOULD NOT HAVE NEEDED TO GET THE EXTRA 4 FIXED ONES, ONLY TWO OF WHICH I CAN USE! SO THE PRICE BELOW SHOULD HAVE BEEN LESS THAN HALF FOR STEEL RATHER THAN ALLOY PULLEYS. YOU CAN SEE IN THE PICS BELOW THESE HAVE INDIVIDUAL PART NUMBERS, MAYBE JUST THE ONES NEEDED COULD BE ORDERED, PLEASE LET US KNOW IF YOU FIND OUT.IT IS INTERESTING THAT THE KIT IS MAINLY MADE FOR PEOPLE THAT WANT TO PUT LIGHTENED PULLEYS ON ALREADY ADJUSTABLE CAMS, I AM WONDERING HOW NOTICEABLE THE DIFFERENCE WILL BE JUST FROM GOING A BIT LIGHTER - THE BACKING HUB IS STILL STEEL OF COURSE.

but I am going to get the lightened Ergal ones which, as it turns out, are identical to the still available DP 2 valve 18T kit (part #96436503B), so you just buy two kits! EACH KIT HAS TWO ADJUSTABLE PULLEYS AND TWO FIXED PULLEYS $286.48 EACH = $572.96 (IE. AVERAGE PRICE = $71.62/PULLEY)

Plus if you have a 916/748/996 motor get the 4 inner spacers (part #71310071A), WELL I DON'T!!!

THAT IS A TOTAL OF $828.28 + BOLTS (SAY ANOTHER $10). THESE AMOUNTS ALL INCLUDE GST

Brett:
This is another good write up Vince.  Well done.

VinceS:
You may have heard how important cam timing is to smooth operation, power and longevity of a Ducati (or any) motor is and, like I, been meaning to get around to getting the cams "dialled in" for ages? Which basically means set the timing accurately to factory specs. This is more of an issue for older bikes as they started putting adjustable cam pulleys (pullies?) on in early 2002 - and then it was as easy to put them in the right place as the wrong one so the odds are better they are OK. Although, from the attachments, it appears there are reasons they can become a bit out in normal service. Not sure where that is enough to matter, but very sure the original set-up is more luck than good mgt.

The problem is it is now getting more expensive to fix up the sloppy factory tolerances. I have just ordered the relevant parts (details below) from Frasers and it has cost me about 50% more than it would have 12 months ago. Sheesh! But I also figured I should put the info up since I have gathered it all now and ordered the parts. May even do a bit of a "how to" later, we?ll see how we go there! I have attached a couple of guides by others to this post, and they cover it pretty well (too well!). Plus a couple of pics from my last attempt.

My particular awareness of this issue stems from fitting a Power Commander 3 which tweaks the fuel injection to smooth the torque out and improve rideability. This was on the 2003 ST4S and I had checked the cam timing was correct before fitting it. The PC3 is dyno'd to the bike and gets the results by smoothing out the air fuel ratio across the rev / power spectrum, very clever really and well worthwhile. However, as many know, on the way to the Canberra NDR a while back I was looking in the mirrors for way too long and not at the road which was suddenly covered in sand, so I got a 2001 ST4S with much less km. I put all the goodies from the old bike across including the PC3 for a while, then took it off! The map that was perfect in the previous supposedly identical bike but actually made this one slightly worse. My presumption is that the cam timing was not done quite so well on the older bike and this matters, a lot!

The conventional Ducati way to fix the problem was to buy offset woodruff keys in 2 degree steps to 10 degrees, which gives you an idea how inaccurate they already accepted their original set-ups were! These were always a very fiddly PITA solution, and appear to be no longer available anyway. STM made adjustable cam pulleys, also no longer available. Vee Two, a once great WA company have been swallowed up by a corporate giant and have little interest in retaining this product line. I spoke to a quite frustrated employee in the place the other day, he obviously wishes it was different, believes they will make some more one day, but has no stock and no dates! Last stock moved out in November just gone. They are in the process of stripping out the old website, clearing out stock on Ebay and having some sort of rebirthing, scant details of which are currently available.

DP (Ducati Performance) also used to make an 18T 4 Valve Ergal kit (96436903B Kit Puleg.ERG S4-S4R-ST4-ST4S Ergal Roller Kit) but it is no longer available. Cam pulleys come in 18 "teeth" and 20 teeth versions, I'm not sure which models used the 20T but my 4 valve  '01 ST4S and many others use 18T so I haven't looked into that aspect further.

If you want to know what you have it is easy to find out, changing it is another matter! Just lift the fuel tank and undo three cap screws that hold one of the cam belt end covers on and you can see the belts plus the top (cam drive) pulleys. You can easily count how many teeth you have. If the pulleys have three allen head bolts in their webs you are adjustable, so the only issue is whether you want to get the cam timing adjustment checked - which doesn't take long (for someone that knows how to do it) so should be fairly cheap.

Or do the cam timing yourself. We have degree wheel faces in the Technical section of the website (www.hunterdog.org.au/TechnicalInfo.htm) or just use this one www.hunterdog.org.au/GeneralInfo/DegreeDucatiTwin360CW.bmp. You need a flat circular metal plate to stick that to (or buy a degree wheel, typically $150+) and you need a pointer made of wire and an adjustable piston stop made from an old spark plug. Also a dial indicator and a way to turn the engine accurately (I intend to improve on the 'cheap engine turner' I used last time per below). I just bought the cheapest dial indicator going from Toolies last time I did this job, which has a limited range of arm adjustment and I wound up making clamp on steel plates to get the thing in a more useful place to get at the cams to measure lift. Dunno if there is a better arrgt for arms (longer especially) or optional accessories, but definitely worth checking out if you buy one. They do make a 90 degree end style dial indicator which would be much easier to use. I was estimating the angle I se the thing uo at and doing trigonometry to figure out what 1mm of lift looked like at the ridiculous set-up angle I had, I need to improve on this for the next go - but the last time I had adjustable pulleys fitted and found they were only 0.5 degrees out, I didn't think I could do better!

As an aside, in finding the above degree wheel reference I also discovered the whole General Info folder on our website had been deleted. Gawd knows when that happened but it means a lot of things wouldn't have worked, including membership forms and who knows what else. Dunno how long / how / why - and nobody has complained? Bizarre and a bit of a worry, but fixed now.

OK, back to pulleys. I poured over the spare parts catalogues (start here http://www.ducati.com/en/bikes/service/parts/2001.jhtml) to verify other info I found on the web and it is all very consistent. The valve drive train is shown under Head (Head: Timing in the later models) around page 65. For both styles there are basically 5 bits on the end of the cam. An inner spacer, a backing hub, the pulley, a front washer and a special "elastic stop" nut. The adjustable one has 3 bolts as well. For mine the part numbers for the bush and nut were the same for both types. Only the three bits between them were different for the adjustable type. Worth checking for your particular model, but the possibility of variation in the other two bits is not clearly covered in discussions I have found on the topic. However, one reputable source seemed to say that the inner spacers would also need to be changed to do this mod to a 916/748/996 motor. The problem in being certain here is different people seem to use different terminology, so it needs checking in black and white if this is your motor.

So what you need to get from the later ST4S or S4R monster for a 4 valve is 4 pulley inner flanges (part #16010761A), 4 special pulley washers (part #85211241A), a dozen 5x14mm allen head bolts and 4 pulleys. The bolts are part #77150402B but I am just going to get these from a local bolt supplier. The pulleys you could get the stock ones (part #25510141A) but I am going to get the lightened Ergal ones which, as it turns out, are identical to the still available DP 2 valve 18T kit (part #96436503B), so you just buy two kits! Plus if you have a 916/748/996 motor get the 4 inner spacers (part #71310071A), but check your part numbers first as you may already have these. Just for completeness the special "elastic stop" end nut is part #729441542.

Enjoy............!

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