valve clearance discrepancy

[Guest ratchethack]

Assuming that the v11 and probably already the 1100S have modern camshafts built in (some say these are US origin since Dr.John), it's quite important to adjust the clearance to the value the cams were designed for.

The reason is that nowadays before the lifting phase or lifting ramp of the cam there is a small ramp that first closes the gap and then more or less softly begins to accelerate the valve. If you choose the valve gap too big the cam "smashes" against or in the lifter like it was common practice in the really old days.

 

There can be of course improvements in terms of idle or lowend performance, but in terms of noise and durability the gap has to be precisely met. Well, now to the beginning of this thread, what do the Italians think the correct value should be...

 

Hubert

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Hubert, this makes perfect sense to me, but seems a bit counter to conventional practice. Not that this would put the likes of me off, y'unnerstan' . Taking the most extreme example from a well-known shop that specializes in valvetrain work, Raceco publishes the following on their Web site:

 

Two valve engines

 

Tappet clearances for the Guzzi big twins should be set to 0.20mm for the inlet and 0.25mm for the exhaust. This also applies to the "modern" Guzzis such as the Sport 1100, Cali 1100i and V11. The factory settings for these bikes are 0.10mm and 0.15mm respectively, but this is to try and reduce engine noise to meet US emissions regulations. With tappets set this tight the engines have trouble ticking over and running cleanly at low revs.

 

So would you say this is more of a matter of opinion, splitting hairs, or ?? BTW - what clearances do you run in your '00 Sport? Many thanks for your input.

[Guest trispeed]

Thanks, I guess I'll go with the bike sticker that says .15mm in.; .20mm ex. and this is on a California spec machine

[jrt]

Thanks, I guess I'll go with the bike sticker that says .15mm in.; .20mm ex. and this is on a California spec machine

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They're ALL California spec machines. No difference between yours and anyone else's with the same year.

 

Has anyone cooked a valve from setting the valves to the closer tolerances?

uh, yes. A long time ago on my tonti frame.

[helicopterjim R.I.P.]

uh, yes.  A long time ago on my tonti frame.

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Was this set to a published tolerance? Did you recieve any recompense from Guzzi?

[Guest trispeed]

that was meant for the international folks, as some have been under the impression that California had some .05mm/ .10mm specs. Maybe I should have said "50 State" spec. At any rate, my bike says .15/ .20mm

Thanks.

[Martin Barrett]

that was meant for the international folks, as some have been under the impression that California had some .05mm/ .10mm specs.  Maybe I should have said "50 State" spec. At any rate, my bike says .15/ .20mm

Thanks.

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My understanding was that California has the most stringent noise and emision tests. So that the US bikes are all made to that standard. Hence the delays in the Breva etc , making a 50 state model. Tend to use the expression to show that standard. Most bikes are modified , lose the emisions gubbins and tip over canister and run the more liberal European settings.

[Guest trispeed]

you're right about California and we often get our own spec machine/ the remaining 49 states, yet another.

There was one time I remember where that was to our advantage, though. The venerable FZR 600 ( late 80's- 90's) Cal spec model had the EXUP valve where the 49 stater didn't. This was most beneficial to the mid range power with no ill effect on the top end.

[pete roper]

I have never actually heard of anyone burning a valve with the very tight US specs although I have heard of cases where people have experienced poor running at idle after a long hard thrash in hot weather. Whether this is down to the too tight clearances or some other problem I don't know but there are probably large numbers of Guzzis in the US running with the tighter specs with no ill effects.

 

My own personal observations are that running the Raceco specs is competely un-neccessary. The old roundfins ran 8 thou, (0.2mm) inlet and exhausts but they a.) don't dump heat as well as the squarefins, b.) use cast iron rocker carriers with a lower C of E and c.) were designed to sit idling in Milan traffic with a fat copper sitting on them. all things that will tend to lead to the need for a wider clearance. I run my old roundies at 4 and 6 thou in winter and 5 and 7 in summer, (If and when I remember to check the valve clearances, usually happens about every 18 months-2 years! ) I've never burnt a valve yet. Any squarefin should be quite happy with less than that! As for the question of hammering the tappets due to wider clearances jumping the ramping? Nah, don't think it's that much of an issue really, even the V11 cam is not really particularly wild in any real terms, although some bikes do seem to change their breathing sufficiently to upset the FI if different clearances are used.

 

For what it's worth I'll be running my Griso at 4 and 6 thou as that's wot the book sez, once the rocker spindles andd bushes have worn a bit though, (And they do.) I'll probably close 'em up by a thou. As I've said before, it's not a two wheeled Ferarri, it's a Briggs and Stratton ditchpump, service it regularly and treat it well and it will repay you with long and enjoyable service but fretting yourself into a pink fit over whether the valve lash is set to one or other of the specs really isn't worth it.

 

Pete

[jrt]

Was this set to a published tolerance? Did you recieve any recompense from Guzzi?

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Oh, no. It was my own stupidity. I think I ran the bike too lean for too long with tight valves. Eventually (30,000 miles in or so) I burnt an exhaust valve. It wasn't at all the fault of the manufacturer.

[luhbo]

Hubert, this makes perfect sense to me, but seems a bit counter to conventional practice.  Not that this would put the likes of me off, y'unnerstan' .  Taking the most extreme example from a well-known shop that specializes in valvetrain work, Raceco publishes the following on their Web site:

 

Two valve engines

 

Tappet clearances for the Guzzi big twins should be set to 0.20mm for the inlet and 0.25mm for the exhaust.  This also applies to the "modern" Guzzis such as the Sport 1100, Cali 1100i and V11.  The factory settings for these bikes are 0.10mm and 0.15mm respectively, but this is to try and reduce engine noise to meet US emissions regulations.  With tappets set this tight the engines have trouble ticking over and running cleanly at low revs.

 

So would you say this is more of a matter of opinion, splitting hairs, or ??  BTW - what clearances do you run in your '00 Sport?  Many thanks for your input.

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They then IMHO probably have problems with carbon and fuel emissions as well, as with valves set tighter the losses at lower revs should be remarkable higher then with bigger lashes. That's why the engine does not idle as smooth as you may want it to do.

 

I have set mine to 0.15mm inlet and 0.20mm outlet valve. This works fine in my eyes. I have made the experience that the older bikes like my LMIII or 750S don't like these values, they run better with 0.25/0.25. And I can set the lash to what I want, they never run as calmly as the V11 engine does! I'm sure that the cams definitely have seen a lot of developement since the late 80ies at least.

 

Hubert

[docc]

:

 

 

For what it's worth I'll be running my Griso at 4 and 6 thou as that's wot the book sez, once the rocker spindles andd bushes have worn a bit though, (And they do.) I'll probably close 'em up by a thou. As I've said before, it's not a two wheeled Ferarri, it's a Briggs and Stratton ditchpump, service it regularly and treat it well and it will repay you with long and enjoyable service but fretting yourself into a pink fit over whether the valve lash is set to one or other of the specs really isn't worth it.

 

Pete

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The Breva/Griso don't get hydraulics? Seems Aprilia thought it's wot the old guys want . . .

[pete roper]

The Breva/Griso don't get hydraulics? Seems Aprilia thought it's wot the old guys want . . .

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The Hydro motor was specifically developed for the Cali series bikes because, I suppose, they were expected to be owned by high mileage cruiser/tourers who wouldn't want to have to adjust stuff out on the road. There is also the fact that the Cali market is dominated by people who like the idea of mechanically silent, low maintenance bikes. Certainly the Hydro motors, when they are working well, are lovely. I'd have one in a trice. In fact I'm still tempted to see if I can get one really, really cheap in a couple of years in the USA and leave it there with a Mate, (After I've got Mike Haven to do whatever wonderful thing MPH do to them!!! MPH have had ZERO cam failures on the hydro models so whatever they're doing they're doing it right!!!!! ). Having aHydro EV waiting for me to go touring in the USA when I visit would be the lap of luxury and an exhibition of decadence hithertoo unseen in the western world!!!!

 

Pete