valve clearance discrepancy

[Guest trispeed]

Hi all, checking my valve clearance for the break-in service. The manual states .10mm in./ .15 mm ex/ ; the sticker on the bike itself says; .15 in/ .2 ex =/ - .02mm.

any comments re: proper clearance values? Thanks

2004 V11 sport usa model

[coz1100]

I go with .2in/.25ex. If I remember these numbers vary from person to person. Maybe try a search and see what you find.

 

 

Just my

[dlaing]

I go with

.15mm intake

.20mm exhaust

Opinions vary, but for most people the bike idles better with numbers larger than .10/.15mm

RaceCo recommends the numbers that coz uses.

[Guest trispeed]

thanks guys,

is there really this much latitude with the clearance values? Which would you believe; the owners manual or the on- bike sticker?; my Aprilia had an incorrect sticker on it recommending 20/50 oil whereas the correct was actually 5/40?!?

[BrianG]

thanks guys,

is there really this much latitude with the clearance values? Which would you believe; the owners manual or the on- bike sticker?;  my Aprilia had an incorrect sticker on it recommending 20/50 oil whereas the correct was actually 5/40?!?

64336[/snapback]

 

Actually, you can tune your cam to a pretty significant degree with a solid-lifter arrangement like the Guzzi has. It's a trick us old hot-rodders used to use with our street-driven, wanna-be drag-strip cars. Our too-hot race-profile cams became almost streetable when we opened the clearances. Of course header pop, and lifter racket also defined "gearhead kool" back in the day......

 

Opening the clearances effectively shortens the duration/overlap of the cam profile. This contributes to better low end power and smoother idle by increasing combustion pressure and retention.

 

Tightening the clearances effectively increases duration/overlap, and enhances high RPM power by adding intake fill-time, and facilitating exhaust scavenging with longer valve-open time.

[Guest trispeed]

excellent info, thanks.

I am most interested to know if there is a specific clearance range that is best for engine/ valve train reliability/ durability, etc.

[jrt]

The 'world spec' numbers of dlaing's are probably safest. They certainly make the bike run well. The range is anywhere between coz's numbers and the tightest ones listed. So- intake 0.1-0.2 and exhaust- 0.15-0.25. Anything much tighter and you'll risk burning a valve. At the worst, you can drive the valve into the piston, but I don't know enough about piston/valve clearance on the V11 to give you a valve setting that would cause interference. Much more likely is the 'burnt valve' scenario. Too loose and you'll hammer the valve train.

I like to set my valves on the loose end of the spectrum, and in several hundreds of thousands of miles, I haven't worn out a camshaft. I have worn out lifters and pushrods, but it sure takes awhile. This is a case where there is no specific setting that is best- there's a range, so experiment and see what works best for your bike.

[Guest Nogbad]

Within reason, a tappy tappet is a happy tappet.

[Guest trispeed]

thanks a lot!

[big J]

If you have metric inches on your feelers, it's .004" and .006"

[quazi-moto]

Middle ground would be:

Intake: .006

Exhaust: .008

[quazi-moto]

I have to agree with Nog. I'd rather hear 'em than cook 'em!

[helicopterjim R.I.P.]

Has anyone cooked a valve from setting the valves to the closer tolerances? I agree with BrianG's post that it is mainly to improve low end response. I didn't think that setting the valves to the minimum lash would damage the bike. I'll have to check mine!!

[Martin Barrett]

Middle ground would be:

Intake: .006

Exhaust: .008

64530[/snapback]

 

I thought:

.002" & .004" California specs

.004" & .006" Europe specs

.006" & .008" Raeco specs

 

When I did mine I couldn't find my metric guages so a quick google threw up 6&8 thou so I set those. It was only later that I realised they were the widest, no wonder it's a bit tappy

 

But as always I could be wrong (need a smiley with a huge hammer)

[luhbo]

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