Strange Metallic Rattle - Champagne Edition

[gstallons]

You don't have to put expensive , elaborate stuff in there to take up this slack.. 

something good . Maybe a good experienced man can chime in ?

p.s. call a machine shop Monday w/some dimensions , they can help you

[Scud]

OK - so here's what I did:

• Assembled the rockers on the tower - the intake side made the same noise as the video. So that's isolated from the pushrod, valve guide, etc. 
• Found the stiffest spring from the original motor (which had 50,000 miles). There were noticeable differences in spring stiffness.
• Installed that spring - still made the noise.
• Then I assembled it with an extra washer (non-expensive, non-elaborate) - a thin one at the top of the shaft, not one of the thick, brass washers. Noise is gone. There is still free-play, but it is less than exhaust side.

 

I am tempted to put it all back together and start it like this. Do you see a risk if I do that?

 

This would only be short-term. If that eliminates the noise, then I would get all new springs and washers.

[coreytrevor]

I would think even if there's a bit too much pressure with the extra washer it would take quite a while to hurt anything.

 

Just don't take any long trips.

[68C]

Possibly the end of the thackery spring/washer had worn to a sharp edge and was catching on the arm or the support, then it wound up a little before releasing. Might be worth rounding the ends of the washer.

 

It used to be a common mod to remove these thackery washers and shim out the gap to reduce friction, it was a little noisier of course but not important when racing. Ideally you only want a few thou clearance when hot, first of all set the gap to around 0.010" then get the motor hot, quickly check the hot gap then add/remove shims to set the gap to a few thou.

[Chuck]

 

 

On that bearing... is that something you've done any maybe could find a part number?  If not, I can take measurements and try to find the correct bearing.  I might like to test that bearing (or new springs) before doing anything else. The spring has a washer on each side. Would the bearing replace all three parts?

Brad (The Kid) used the bearings in his 1100 Spot. I'll shoot him a text and see if he still has the part numbers. They were inexpensive..

[Chuck]

He's as bad as me about carrying a phone. He may or may not answer a text today. Some work with calipers should get you the answer.

https://www.mcmaster.com/#thrust-washers/=19x8u71

You need the thrust/needle bearings, of course.

Ace told me he experimented with running with a valve cover off at high rpm (kind of messy)  and the pressure of the pushrods moved the rocker arm back and forth in a blur. He assumes that eats horsepower, and came up with this bearing idea. 

[JRD]

Chuck, maybe you can answer this.  If that rocker arm has been moving sideways across the valve stem, is it possible it could be pushing the valve stem sideways instead of straight up and down?  This would cause the valve guide to wear in an oval/oblong shape?

The only reason I ask is this was a major design flaw on the old Triumph T150/T160's.  Poor valve train design and valve guides would be worn out with 14-15 thousand miles.

 

Since Tim has the heads off do you think he should check the guides now? 

[Scud]

Chuck, maybe you can answer this.  If that rocker arm has been moving sideways across the valve stem, is it possible it could be pushing the valve stem sideways instead of straight up and down?  This would cause the valve guide to wear in an oval/oblong shape?

The only reason I ask is this was a major design flaw on the old Triumph T150/T160's.  Poor valve train design and valve guides would be worn out with 14-15 thousand miles.

 

Since Tim has the heads off do you think he should check the guides now? 

 

Interesting theory... I was wondering what other effects there would be if the rocker arm was sliding too much.

 

However, the heads, exhaust, throttle bodies... all back together now. I should have an update in a few hours. Noise or no noise? Place yer bets...

[Chuck]

I'm betting that is your noise. What do I win?

[Scud]

Sadly, you win nothing. I just fired it up and the noise is the same.

 

I think she's going to have to sit in the corner for a few weeks.

[Chuck]

Crap. At any rate, here's the bearing number..

http://www.mcmaster.com/#5909K13

and the washers

http://www.mcmaster.com/#5909K73

I've been meaning to do it when I get a a round touit, but haven't done it yet..

[gstallons]

Scud , remove the valve covers & spark plugs . If you have a center stand , put the bike in gear and rotate the engine until you reach TDC and inspect the valve clearance . When you are  

satisfied with rotate the engine til you reach TDC on the other cylinder . Adjust this cylinder also . Check everything again to make sure you did not make a mistake . 

     Let me know what you find .

[Scud]

When I reassembled, I set valve clearances on both sides to .006" Intake and .008" Exhaust. I did it exactly as you described using the Moto Guzzi shop stand. I think I must have adjusted the valves at least 5 times in earlier efforts to solve this.

 

I've got a busy week ahead and a possible road trip this weekend. I'll get back to this when I can. At that time, I think I should probably drop the sump and pull the heads, barrels, and pistons - and maybe the camshaft, depending on what I find.

[gstallons]

Hmmmmm. Good luck

[coreytrevor]

Crap, I had my fingers crossed that was it. At least now you can enjoy a more involved learning experience than you hoped for.