Raceco valve clearance specs.

[Guest Thundering Subash]

I adjusted my valves this last weekend at 5,000 miles. At the first service I went with .006 intake, .008 exhaust. This time I decided to go to the Raceco specs. (.008 intake, .010 exhaust).

 

My observations are as follows:

 

1) They ARE noticeably louder (even my wife said so after hearing me start the bike after "tinkering" with it all morning). That's fine with me though. One more thing to explain to the wet clutch hydraulic lifter crowd when they ask "why is it ticking" or "is their something wrong with your bike". I end my explanation with "a tappy valve is a happy valve" and/or "loud clutches save lives" which seems to explain it all and make people understand that it's a cool mechanical thing, not a bad thing.

 

2) The bike seems to be just a tad more responsive, and I have yet to experience the hesitation or sputter I previously saw on occasion while when taking off from a traffic light after the motor was fully warmed up, coming off the freeway, and sitting at the traffic light for a minute or two. Time will tell on this one, but I don't think that issue will return (and based on Al's experience, is a consistent benefit of loosening up your valves).

 

3) It now idles nicely at EXACTLY 1,000 rpms, whereas before it idled not as well at around 900 rpms. This further confirms to me that the bike is happier adjusted where it now is, and perhaps where it was meant to be (I don't think the idle has changed at all since the bike came out of the crate, as all the yellow paint lines still match up).

 

4) Can anyone explain to me any down sides to having your valves set this loose? Would you have further benefit or detriment to going even looser?

 

Lastly, and mostly unrelated to the above commentary, when you retorque your heads, what's the deal with the 6th head bolt at the back of the cylinder that's covered with an allen head bolt plug? After taking off the allen head bolt plug I couldn't see a bolt underneath. Is this a allen head nut instead of the typical nut on the other head bolts? I'm confused.

 

Ride Safe ALL.

 

-Chris

[Guest Jeff Kelland]

The more clearance there is, the more the pushrod can get thrown off the lifter causing it to "hammer" the rocker into the valve. When the valve closes the reverse happens causing the lifter to "hammer" the cam. This is the ticking you hear. The cushioning effect of the oil is unable to handle the increased load caused by the extra clearance. Add enough clearance and it will beat itself to death. I've never heard of anyone having trouble with the Raceco specs, but who knows how close it is to being destructive. I ran up to .006 and .008 on mine without ill effect. I saw no gain in clearance when I checked the valves. What increasing the clearance does is, change the cam timing. It opens the valves later. It takes more degrees of rotation to take up the added clearance. Remember, the cam is at 1/2 crank speed. It also closes the valves sooner. This has the effect of increased midrange at the expense of top end power. Just what an old guy like me wants!

[emry]

Good explaination Jeff. The part that really entertains me is this whole debate. MG wanted the valves to be set at 0.006" in and 0.008" ex or 0.15mm / 0.20mm. Just check the vehicle service tag that is under your rear hugger on the right side. As Mr. Subash stated the valves do get noisier and you can't skirt those pesky noise regulations. If the dealers would start to adjust the valves to the specs (what was intended, not what was a quick fix) there would be many more happy riders.

[Guest Jeff Kelland]

As a matter of fact, legally, neither the dealer or the owner can make a change that would cause a vehicle to fail the noise test. That's why I only changed my clearances "theoretically', honest! I will attest however, that .006 and .008 does make a significant difference in how these engines run. At these clearances I could not percieve any increase in noise. I could notice, no stalling at stop signs, a smoother idle and power delivery, and far less tendency to ping under load. The engine just seems happier!

[svjj]

I just adjusted my valve too .006 and .010" and my left side is much louder than the right side. The left side has one valve tapping fairly loudly. I have rechecked the valves twice now and they are spot on. Is this normal can one side be louder than the other side? Or am I doing something wrong. My bike seems to run much better this way any help would be great.

 

Thanks

[dlaing]

One other side effect is the TPS readings.

Your TPS will read the same at 1000rpms now as what it did previously at 900rpms.

This is one of the reasons that the TPS should be set with the throttle set screw completely backed out.

If you were to do the readings at idle, you would get a TPS setting less consistent with what is specified by the Guzzi or various websites.

I am suprised you only got a 100 rpm jump.

Mine jumps about 300 rpms going from .10/.15 to .15/.20mm

But it is all voodoo anyhow, most people will find no ill effects.

But a real world consideration would be if you had a powercommander mapped at US spec, the raceco specs would throw it off pretty well.(I believe, but I could be wrong...)

[Mike Stewart]

The more clearance there is, the more the pushrod can get thrown off the lifter causing it to "hammer" the rocker into the valve. When the valve closes the reverse happens causing the lifter to "hammer" the cam. This is the ticking you hear. The cushioning effect of the oil is unable to handle the increased load caused by the extra clearance. Add enough clearance and it will beat itself to death. I've never heard of anyone having trouble with the Raceco specs, but who knows how close it is to being destructive. I ran up to .006 and .008 on mine without ill effect. I saw no gain in clearance when I checked the valves. What increasing the clearance does is, change the cam timing. It opens the valves later. It takes more degrees of rotation to take up the added clearance. Remember, the cam is at 1/2 crank speed. It also closes the valves sooner. This has the effect of increased midrange at the expense of top end power. Just what an old guy like me wants!

Dudes,

 

.010 is not enough cleareance to hammer the cam and or lifters. The tapping noise is the gap being closed up in the valve train and will not cause the valves to hammer the seats out any more than the stock specs. Raceco has been around a long time and they would not steer you wrong. I would rather have a looser valve adjustment than the tight specs. that Guzzi reccommends. I would be more worried that a valve could burn due to lack of clearence. Now by going to a larger lash, you are decreasing cam duration (this is why the bike idles better) which will allow the valve to be closed longer and aiding in a lower valve temp via heat transfering to the valve seat/cylinder head. Also, we adjust our valves cold and as the engine warms up, the lash becomes smaller by .002 to .003".

 

Now if you had a ton of clearence like a collapsed lifter in a good old American Hot Rod, then yeah, you can beat your cam to death. The lifter will hit the cam half way up the ramp which is not a good thing.

 

Many years ago when I had a Porsche 914 (I know VW in Europe), the cam grinder had a huge valve lash spec. (I think it was .012") which I thought was too much. His reason for the large valve lash was to gain low end torque or a more driveable engine. This is true on the V11 Sport too.

 

Anyway, I have a happy 30,000 miles on my 00 V11Sport with the Raceco specs and have no cam/valve issues.

 

Just looking at the other side,

 

Mike

[Guest vkerrigan]

The old 1969 Z-28's had a mechanical lifter cam with .030 lash on both intake & exhaust. Ran fine!.........vk

[Mike Stewart]

The old 1969 Z-28's had a mechanical lifter cam with .030 lash on both intake & exhaust. Ran fine!.........vk

What do you mean old. I remember when those were new!

 

Mike

[Guest vkerrigan]

Me Too Mike!.......Guess I'll go get another Geritol.........vk

[Guest Jeff Kelland]

I had the great privilage of rebuilding a 1970 Z-28 engine when I was just starting out. If memory serves (always questionable at my age) it was a 360hp 350 cid and not a 302 cid.. It had 60000 miles on it and the owner just wanted to freshen it up. Chevrolet used a process called tufriding on the crank. The process caused the diameter of the journals to change slightly and all the bearings were selectively fit. i think it varied about .002 or .003. It had a solid lifter cam and factory aluminum manifold. Kind of a lime green and split front bumper. It had massive midrange torque!!! The lifters were kind of noisey, the crank and rods were louder though after I rebuilt it. That's how I learned about Tufriding and selective bearings Very fortunately, I had done no damage. Lesson learned: it is just as important to pay attention taking it apart as it is going back together.

[Guest Thundering Subash]

Another added benefit above and beyond what I've already mentioned is an increase in gas mileage. I'm now consistently averaging 36 mpg combined city/highway compared to 34 mpg with the tighter specs.

 

Now if I ever get around to some of the other relatively basic tuning suggestions I've seen on this forum (that arguably should have been done before the bike left the showroom), it could run even better and may even get a couple more miles to the gallon.

 

Ride On.

[dshap13]

I just adjusted my valve too .006 and .010" and my left side is much louder than the right side. The left side has one valve tapping fairly loudly. I have rechecked the valves twice now and they are spot on. Is this normal can one side be louder than the other side? Or am I doing something wrong. My bike seems to run much better this way any help would be great.

 

Thanks

Was this ever answered? Just adjusted my valves and it seems like the valves on the left cylinder are louder than those on the right?

 

Any insight would be much appreciated.

[jrt]

I can't tell you why, but I can suggest that this is perfectly normal. Every Guzzi I've ever owned (ok, only 6) had one side louder than the other. As I recall, on mine it has always been the left side as well. Maybe it's a 'feature'.

You could put some of those plastic spacers between the cylinder fins- that can help with ringing (prolly won't help). I read about some folks who glued felt on the inside of their valve covers to deaden the noise, but I wouldn't recommend that.

[Alex-Corsa]

I adjusted my valves this last weekend at 5,000 miles. At the first service I went with .006 intake, .008 exhaust. This time I decided to go to the Raceco specs. (.008 intake, .010 exhaust).

 

 

 

All I know is that clearences are set up and have to do with the camshaft, and Neither Dynotec or Daes and others that do Guzzi's more than 30 years suggest nothing else than the factory specs (in unmodified bike),perhaps a tiny bit more loose but nothing more, and these people know better than anyone else.Believe me they do.

Unless you have changed camshaft and, and and ...., or or or... ,you don't have to alter these clearences.