Cam timing advice

[ahdoman]

Hey all,
I've done a bunch of searching and there's some great info on cam timing but here's my situation; I've got a bit of Dyslexia and it makes it really hard for me to process operations like cam timing. I can get the concept but my brain won't actually do the details or I skip things. As a result I really don't want to try this on my own. There are a couple of local shops that will work on my Paso so I'm going to take it to one of them (I need to get belts changed and valves adjusted already). I also want them to check my cam timing but I would like to have some values to have them set the bike up at. That's the reason for this post; I've read that the way the Paso 750 came from the factory was not necessarily set up the best. I've been trying to get my Weber to work and I'm at the point of suspecting the mechanicals of the bike. I use the bike for sport touring so I rarely ever run it at the high end of it's rev range. I'm looking for values that I can give the mechanic to set the bike up to. Is that a doable thing or am I just wishful thinking?

[higgy]

All you need can be found in the documents section here from the main page

[ahdoman]

So from the "specs" page I see these values;

Inlet valve: 41 mm diameter
Opens before TDC 31 degrees
Closes after BDC 88 degrees
Exhaust valve: 35 mm diameter
Opens before BDC 72 degrees
Closes after TDC 46 degrees

I assume these are stock. Are they really the best settings? Are these the factory settings?

[higgy]

http://ducatipaso.org/docs/general/Paso ... g%20v2.PDF


read this one

[ahdoman]

Hey Higgy - I've been through that document a bunch and it's really impressive (I think that's your research?). The problem is there's no way I'll get a mechanic to take the time to read through that. If I show him pages 15 & 16 is that enough info? If I have him set them at 106 degrees I'm worried about the statement "The most a cam should be advanced to is 105 degrees".

[Mc tool]

Any half decent mechanic shouldn't need this explained to him. I dunno how near you are to a reputable mechanic but you really do need someone familiar with the ducati way , problem is that a lot of bike shops see our beloved paso's as a whole pile of trouble that will probly bite them on the arse if they touch it. Ahdoman , I think that if you can remove and dissassemble your carb ( is it back together yet ) then you might be the guy for this job ( getting tools may be the stopper as you will need a dial gauge and mount and a degree wheel ) . Read old posts ( weberology ) , and have a look at the interweb thing ( there are some good moving models of the desmo system working ) , Ducatisuite.com has some vids showing some routine maintainance being done . This is not hard but it does take a bit of thinking about so dont be in a hurry , Oh yeah ... whatever you do do get some MBP valve collets .
I find that if I read the books and look at the job ( mental and eyeball ) over a few evenings , by the time I start the job I feel almost like Ive done it before.
The 105 degrees thing is probly related to piston / valve clearance , which , of course changes when you change valve timing , and there is a limit as to how much you can alter valve timing without giving some consideration to this clearance, but if you are setting it up as per factory you wont have any issues

[higgy]

The cam doc is not mine, it was put together by ab Aussie gentleman you will find here from time to time, Ken

As Mctool said any decent tech should not need it. It was written for the DIY guy willing to take the time to learn.
Tools can be made or acquired for not a lot of money. Follow the doc and you will be fine. With the collets it is a lot less effort. Putting the stock half rings in and out can shall we say be a challenge especially for those of us on the older side of dexterity or who like Mctool and I learn things the hard way

[jayh]

Is the cam timing going to be that far out from the factory that your bike won't idle properly ? I doubt it,your problem most probably lies elsewhere.Some knucklehead may have incorrectly adjusted the valves for instance (I hope not) ,but it is unlikely that he also incorrectly adjusted the cam timing.I'm not saying it couldn't be part of the problem,but I'd be looking elsewhere to start with.Weak ignition perhaps,start simple, like plugs,leads, pickup air gap etc.You may have already done this but something far simpler than cam timing is most likely to be the culprit,save the fine tuning for further down the track when you have the major issues sorted. JM2CW J.

[Mc tool]

Is the cam timing going to be that far out from the factory that your bike won't idle properly ? I doubt it,your problem most probably lies elsewhere.Some knucklehead may have incorrectly adjusted the valves for instance (I hope not) ,but it is unlikely that he also incorrectly adjusted the cam timing.I'm not saying it couldn't be part of the problem,but I'd be looking elsewhere to start with.Weak ignition perhaps,start simple, like plugs,leads, pickup air gap etc.You may have already done this but something far simpler than cam timing is most likely to be the culprit,save the fine tuning for further down the track when you have the major issues sorted. JM2CW J.

bikes leaving the factory with one or both cams out by up to 10 degrees ( crank ) isn't unheard of

[jayh]

Yes Mctool,nobody is disputing that they leave the factory with the cams out of adjustment,but nobody buys a bike that won't idle below 1200 rpm (or something like that),so more likely than not his bike idled at 700 or 800 rpm when it left the factory and should still be able to now.Unless I'm mistaken, he is asking for advice on cam timing to solve his other problems and I believe thats going off on a tangent,the problem most likely lies elsewhere and his time and money could be better utilised at this stage. J.

Ps I idle mine at 1200-1300rpm when hot for best performance,Im not saying that 700-800 rpm is the correct idle setting,I'm just using that as an example of what a normal untuned pantah engine will idle down to.

[Mc tool]

There is No point in trying to fine tune an idle on a carb which has 1 barrel per pot if the two pots are ( valve ) timed as much as 10 degrees apart. There is also no point in blaming the crack in the carb untill you have either eliminated or made allowances for other (known ) possible faults . What I was trying to say is that if you were to try and "tune" your way around this crack in the carb ( and its possible influence ) by using a vacuum gauge to set idle mixtures , you need to at least be aware of the cam timing issue.Now that I am aware of the timing issue I can see its effect on my vac gauge ( Im not saying that I could diagnose it with a vac gauge ... but once you know its there you can see it ).Personally , I think that neither the crack or the timing are solely responcible for the fault as described.

[Duc906]

If you 2 gentlemen have finished comparing the size of your dicks we might be able to help our fellow pasoist.

Hey Higgy - I've been through that document a bunch and it's really impressive (I think that's your research?). The problem is there's no way I'll get a mechanic to take the time to read through that. If I show him pages 15 & 16 is that enough info? If I have him set them at 106 degrees I'm worried about the statement "The most a cam should be advanced to is 105 degrees".

I really need to update that article. I’m not an expert and the article was intended as a “how to” guide for the person who wants to work on their own bike not as a bible.
The recommended minimum clearance between valve and piston should be no less than 1.5mm (60 thou). The "105 deg" measurement refers to the most the inlet cam can be advanced to before this clearance is decreased. I set my cams to 106 degrees after I spoke to Brad Black and he recommended that this, in his opinion, was optimal for the 900 2 valve engine. Brad has done a lot of research on cam timing and is one of the most knowledgeable people on Ducati tuning that I know of. I tried a few different settings from 112 down to 106 degrees and while the changes were barely noticeable I did find that the bike started and idled better and had slightly better drivability around town when I had the cams set at 106 degrees. The annoying backfire issue I had nearly every morning I started the bike also disappeared.
Having said all that, these measurements are for the cams in the 900 engine not the 750. The cams in the 750 engine have a different centreline so the minimum degree setting will also be different and as I don’t have a 750 to play around with I can only point you to Brad’s web site where he has detailed cam timing information on several models including 750’s. Here is the link to his site, http://www.bikeboy.org/index.html , click on the “reports” tab and scroll down to 2v Cam Timing . He is also a member of this site so maybe you could pm him to get some more help.
As I wrote in your other thread, I don’t think your idle issues are caused by cam timing adjustment
but from the damage to your carby. By all means get the cams checked if you want, it can only help, but in my opinion you need to get the carby sorted before you start altering your cam timing otherwise you will most likely be chasing your tail and get nowhere and before you know it there will be another Paso being parted out.

[ahdoman]

Duc906 - Thanks for your input and confirming my suspicions; It looked like all of the data you had was for the 906 but it also looked like the application could have been for any of the Paso's, just the numbers might be different. I've been looking on Brad's site but haven't found anything related directly to the Paso 750 so I've sent him an email.

As I stated, I need to get the belts replaced and the valves checked on this bike so I might as well check the timing as well. That way I can eliminate that issue. I am on the hunt for another DCNF. The problem is all the ones I've found are almost as much as doing a Mikuni conversion... anybody got a DCNF they want to part with, cheap?

BTW - This bike WILL NOT become a parts bike. I rescue "abandoned" bikes and give them new hope. I know, it's not a smart and profitable venture, it's a hobby.