timing marks

[Guest frankdugo]

hope someone will chime in &educate me. did not want to hijack john's post.curious minds want to know.are there really bikes out there without fly wheel marks?

[EnduroGuzzi]

My three previous spines had the D and S marks, my current 04 LM does not. I too was puzzled when I discovered that.

[mark.gilmore]

Yes some of them don't.Like Morris Sod's,He is a member on this forum.His RM does not have any marks either.

[Guest ratchethack]

FWIW, the D and S flywheel marks are NOT timing marks. They're TDC marks.

 

My Sport has TDC marks, but no timing marks. Timing marks are of little use, since there's no mechanical timing adjustment.

 

For that matter, per the recent thread on this, TDC marks aren't really necessary either, setting valves being easily enough accomplished -- and 100% accurately -- by "feeling" through the spark plug hole for TDC on the compression stroke (where both intake and exhaust tappets are on the base circles of their cams through the same range of crank and cam rotation).

 

Take a look at how many degrees of cam rotation you have to get valve adjustment right for one valve (see below). It's about 220 degrees. Remember -- the crank:cam drive:driven ratio is 2:1. So at the flywheel, you've got about 440 degrees of rotation where the valve clearance can be set for that one valve. At (and around) TDC, you have an overlap of both intake and exhaust cam timing, where both valves are closed and both tappets are on the base circle. How many degrees overlap is this? Don't exactly know. I reckon I was never curious enough to check on it, but it would certainly be substantial enough to make precise location of TDC completely unnecessary for the purpose of setting valves.

 

typical cam base circle

[renato]

No timing marks on my 03 v11, I would never stick a screwdriver in the spark plug hole,but you can use your thumb over hole and wait for compression or for about ten bucks you can get a top dead center tool, sweet tool it,ll whistle when you get there to top dead center that is

[Guest ratchethack]

There are many ways to skin this cat for purposes of setting valves, but this here cat doesn't need to be all that accurately skinned. A careful feel in the spark plug hole with a screwdriver (or anything else that's handy) presents no risk wotsoever unless you're pretty careless how you go about it, but to each his own.

 

With a finger over the spark plug hole, you can get "in the ballpark" by feeling for when the piston is coming up on the compression stroke. An implement of some kind in the hole to feel the end of stroke, and you're there. A pencil with a nice soft eraser works fine if'n a screwdriver seems too dangerous.

 

As mentioned previously, there's no need to get TDC dead nuts accurate for setting valves, since there's a range of crank rotation on either side of TDC where both intake and exhaust tappets are on the base circles of their cams, and you'll detect no difference in valve clearance in this range. Feeling for this range and getting anywhere in between is pretty easily done.

 

When looking for "exact" TDC without flywheel marks (again, not needed on V11's), I've used a length of old hose shoved into the spark plug hole, with smaller pieces of tube shoved into this ending with a length of clear tubing with little water in it. This serves as a "bubble-o-meter" for determination of TDC, is about as dead nuts accurate as it can possibly get, is lots more expedient than a ride to the local auto parts store to purchase a TDC device, and costs nada.

 

I seriously doubt anybody's M is ever gonna V too much on this one, but then I'm just a shade-tree Road Geez.

[Dan M]

With a finger over the spark plug hole, you can get "in the ballpark" by feeling for when the piston is coming up on the compression stroke. An implement of some kind in the hole to feel the end of stroke, and you're there.

 

As mentioned previously, there's no need to get TDC dead nuts accurate for setting valves, since there's a range of crank rotation on either side of TDC where both intake and exhaust tappets are on the base circle. Feeling for this range and getting anywhere in between is pretty easily done.

 

 

No accuracy needed at all. As Ratch mentioned in an above thread, the back side of the cam is a pretty big place. You can get where you need to be just by watching the valves as you rotate the motor. You don't even have to take the cover off if you have a stand. Just put the trans in a higher gear, pull the spark plugs and rotate the engine easily using the rear wheel. Watch the valve close, turn it slightly farther and adjust. Once the covers are off you can adjust all four valves in less than 10 minutes.

There are many ways to determine TDC from burping it like ratchet describes, a slim screwdriver or straight piece of coat hanger in the spark plug hole or most positively with a dial indicator. Once found you can paint marks perhaps to use checking timing scatter. Beyond that the info is not really needed.

[tmcafe]

No expertise here, but I ended up just watching for both valves close in the right sequence while rotating the rear wheel. Since it takes some effort in a higher gear, it's much easier to do it this way than trying to rotate the wheel while checking for the mark on the flywheel. To double-check, I did take a peak to see if the mark was there, but didn't bother for the next one. Another easy way to tell if you're all set is to try and twist the pushrods--they should spin freely.

[Guest frankdugo]

well,thank's every one. i have used all methods. don't know for a positive fact but in my mind the bike seems to run better using the"tdc" marks. still curious why they dis continued putting the marks on.

[Guest ratchethack]

Frank, I figure it this way.

 

Far be it from me to second-guess why the Luigi's did many things they did. Evidently we all liked wot they did well enough overall, or we wouldn't be here -- we'd be somewhere else.

 

But generally speaking, with all the cost-cutting measures dictated by the bean-counters in Mandello over the years the V11 was in something resembling "production", under more or less continual threat of closing their doors and sending everyone home for canoli's and Moretti's, I reckon if there was an operation that they figured could be eliminated without either a rider OR dealer problem of any kind, they eventually got around to eliminating it.

 

Just the impression I get.

[gstallons]

MOST engines now with DIS do not utilize or need a TDC mark. I don't have to tell you that if it is not needed it is not going to be there.

I do think the flywheel bolt pattern will allow 6 different positions of flywheel placement on the crankshaft. If the flywheel has been removed it might not be indexed properly. Rotate the engine SLOWLY to look for the mark.

[Guest frankdugo]

well, i like moretti rossa& canoli-but not at the same time.

[Greg Field]

Guzzi specifies that valve be checked at TDC. We are all assuming that Guzzi is really specifying that valves be check on the base circle of the cam. This may or may not be the case. UNtil I personally do the work to verify that Guzzi really is specifying that the valves get checked for lash when the tappets are on the base circle, I'll keep doing it at TDC.

 

FWIW, I didn't think I had marks on my flywheel either, so I decided to mark some. Using a piston stop, I found the precise TDC for the left cylinder. After cleaning off the flywheel and looking closely with the aid of a flashlight, I found that there already was a TDC mark there. Same for the right cylinder. YBMV.

[richard100t]

When I bought my bike the tdc marks were very easy to see. Over time the markings have faded & now I need a flashlight to really see them. I've been thinking about remarking them, but I've never gotten around to it. Ratchet is right as well, you just have to be close anyway.

[Guest ratchethack]

Guzzi specifies that valve be checked at TDC. We are all assuming that Guzzi is really specifying that valves be check on the base circle of the cam. This may or may not be the case. UNtil I personally do the work to verify that Guzzi really is specifying that the valves get checked for lash when the tappets are on the base circle, I'll keep doing it at TDC.

Greg, you've got me connoodlin’ things here again, and now I hafta take this the next logical step. . . Y'see, I just gotta. . .

 

Maybe this'll be all the verification you need that Guzzi spec's valve adjustment on the base circle of the cams, just by reasoning things out. Hey -- it could happen.

 

Seriously. I'm not trying to provoke anything like a feud here, but to my understanding, it makes no sense wotsoever for any 4-stroke motor to have valves adjusted at any other point of cam rotation than on the base circle of the cam, when valves are as closed as they get, and the clearance is maximum. The only alternative possible would be to call for valve adjustment when the tappets are on the ramp faces of the cams, somewhere between the base circle, and where the valves start to be either lifted off their seats, or they're just reaching fully seated from having been open. To my way of thinking, this’d be a horrifically difficult way to set valves (using nanotek scale measurements??) and a new one on me, but maybe I’m about to learn sumpin’ here?

 

Think of it this way:

 

At TDC on the compression stroke, where the Guzzi and every other 4-stroke motor I’ve ever adjusted valves on (a fair heap), all have valves spec’d to be set, both intake and exhaust valves have already been closed for approx. 180 degrees of crank rotation through the compression stroke, and both remain closed for another approx. 180 degrees of crank rotation through the power stroke. That adds up to 360 degrees of crank rotation where BOTH intake and exhaust valves are closed. Right smack in the middle of this is TDC on the compression stroke. It would seem that there’s something like a full rotation of the crank available for setting valves, when both intake and exhaust valves are fully closed – that is, both on their base circles.

 

What kind of a 4-stroke motor would differ from this to the point where one or both valves would ever have to be set with their respective tappets somewhere on the “take off” and/or “landing” of the ramp face of the cams??

 

Enquiring minds. . . (well, you know)