[Keef Sparrow]

UCE engines in the 90's?

The AVL designed UCE engine dates from 1995 in 500cc form and from 1997 all 350 and 500 Bullets featured the UCE engine.

[Crabsapper]

2008 for the UCE according to Peter Henshaw's Book.

[Keef Sparrow]

I got my information from Wikipedia (which I know is not 100% reliable) where is says the UCE first appeared in the Bullet Machismo in 1995. I think this model was only available in India.

[Crabsapper]

I got my information from Wikipedia (which I know is not 100% reliable) where is says the UCE first appeared in the Bullet Machismo in 1995. I think this model was only available in India.

That's miles out. The UCE first appeared in 2008.

The AVL lean burn engine was still pre-unit, as was the 5 speed.

[fressko]

btw
this is the sound of a brand new tribute black:

https://www.youtube.com/watch?v=pN-hD5wR2pI

[axman88]

btw
this is the sound of a brand new tribute black:

https://www.youtube.com/watch?v=pN-hD5wR2pI

Interesting!  Also has a fairly obvious "valve clatter", in my opinion.

I'd like to solicit some guidance in what to look for to quiet valve noise.  My 2012 C5 has gotten fairly noisy in the last year, and I'd like to get it back to where it was.  I'm right at around 7900 miles on the odometer.  The machine was quite a bit quieter when I purchased it at 1700 miles on the odo.  Here's more background:
           Around 3000 miles there was a substantial increase in valve noise, but it was intermittent.
           Shortly after this, the auto decompressor cam failed, the pin stayed up and things got quite noisy.  I rode the bike a few miles in this condition, then put it up waiting for the replacement cam.
           Replaced the auto-decomp. cam and adjusted cam backlash and the engine was quiet again.
           Now, 5000 miles later, considerable valve noise is present, but appears intermittently.  I can start the engine and won't notice tapping sound at all, but it will appear later, or will be present on a subsequent startup.
           The sound seems at a minimum when I reduce throttle and cruise at moderate rpm.  Seems at a maximum with the engine under load or idling.
           Tapping seems to be coming from exhaust tappet, but hard to localize.

I've checked the rockers.  The blocks are secure and play in the rocker bushings is minimal.  With the rocker covers off, there seemed to be sufficient oil flow to the intake rocker, and three times greater flow to the exhaust rocker.

I'll try to make a recording next week when it stops raining.  My next thought was to open up the cam side cover and adjust the cam lash.  Is it possible to check the lifters in place?

[Mad4Bullets]

Before tearing everything apart, I'd recommend investing in a mechanics stethoscope for starters.  They handily block out all noise except that being picked up by the probe. This simple tool can really go a long way in helping you pinpoint the source of the noise within the engine.

Based on the numerous videos I've seen out of India, it could be valve lash, failing hydraulic lifters, the decompressor mechanism once again, poor oil flow or something in the intake or exhaust rocker areas. The hydraulic lifters seem to be a common noise producer and replacing them can be rather involved. The top end and piston must be removed, as will the side cover. Other solutions are a bit more forgiving.  All can be done with time, patience and basic tools. And of course encouragement from the forum.

[Crabsapper]

Thanks.

Here's an update:

Bike has been stripped at the dealers and the fault is with one or both of the hydraulic lifters. New parts are on order and the bike will be repaired under warranty.

 

[johno]

That's good news in a way, make sure they examine the top of the push rods and rocker boxes for hammer damage.

[Crabsapper]

Further Update:
Thought it was too good to be true. 
After being told we were waiting for stock, I chased up again today (I have to chase, not once had them call me) I'm now told the lifters are "under study with the technical department" and we should hear "soon". Yeah, right.

I'm assuming that's at Moto GB.

The dealer will chase again tomorrow.
So who knows. Is this them trying to find cause to wriggle out of it?
Not great service.

[Crabsapper]

Got the bike back today with new lifters, supped and fitted under warranty. 

Was noisy on start up, but I assumed it just needed the lifters priming.
A few minutes later, nice and quiet.

By the time I got home (about 35 miles) the noise had come back.

[Crabsapper]

Does sound a bit tappety.
Have you ever had the cam backlash checked or adjusted?

I noticed today that the noise disappears when the engine is under load, but us very pronounced when on the overrun.

Does that point at cam backlash?

It suggests to me something that alternately has play, then hasn't. Does excessive cam backlash create a bigger tappet clearance in one direction?

[Crabsapper]

Latest update on this is that a new cylinder head is required and is on order.

[Haggis]

Say what.?
Whats up with the cylinder head?
Do you have a loose valve seat?
Not much in a head that will make a noise, valves and their seats are all you have.
No point in just throwing parts at it.

[Richard230]

Say what.?
Whats up with the cylinder head?
Do you have a loose valve seat?
Not much in a head that will make a noise, valves and their seats are all you have.
No point in just throwing parts at it.

I thought throwing parts at a problem was the modern way of fixing things nowadays.