[barenekd]

WillW,
My engine is clattering and sounds like what you were describing when you were having troubles with your engine. I know what mine is, though. It's the compression release mechanism. It only does it on cold starts, down around 40-50 degrees. It was giving me fits yesterday. the engine would start then quit and attempted restarts flooded it. It was a pain as the decompression arm is clattering away. Finally got it cleared out so it would run, and as usual once it warmed up a bit it stops banging around.
So in the spirit of old aviation mechanics, I'm going to dump a little Marvel Mystery Oil in the crankcase and see if that frees it up so it will work properly. Otherwise, I have too pull the timing cover off to fix the seeping, so then I can take a real look at it. I'm waiting for gasket so I can take the thing apart.

[Ducati Scotty]

With the colder weather I've been getting some decompressor clatter on start ups too.  Usually clears up with a few gentle twists of the throttle.  In warm weather I never hear it.

Scott

[Maturin]

When it´s really the auto decompressor then it´s probably not necessary to worry much. Mine clatters occasionally after cold starts since 10´kms. The colder the ofterer. Then there is a somewhat loader "clunck" and it´s released, stops clattering and runs normally.
With regards to the gasket: it doesn´t have to take much oil pressure and I had no problems to remove it and reuse it afterwards.
But tell us, Bare, which kind of witch powder do you inject into your oil pot?
Regards

[Fox]

With the colder weather I've been getting some decompressor clatter on start ups too.  Usually clears up with a few gentle twists of the throttle.  In warm weather I never hear it.

Scott

+1 on a blipping the throttle a tiny bit. Once it snaps out of it, it's usually fine.

[Ducati Scotty]

Marvel mystery can't hurt.  If there's a bit of carbon or sludge it should help clean it up.

Scott

[2bikebill]

I still don't know what the cause of my clattering engine was. I do know they removed the auto decompressor the first time the bike went in, but it made no difference. I never really thought that was the cause - it'd given trouble early on and was a much different sound. The later bothersome clatter was continuous, and louder when the engine was at full running temperature.
Mike at WS was going to let me know exactly what has been replaced this time, but he hasn't got back to me yet - they're a bit like that at WS.....
He did say during an earlier phone conversation that they never found anything they could pin down as the specific cause. I do know the main bearings and the piston rings were replaced, but not sure about anything in the valve train.
I only got to ride it twice for about 50 & 30 miles before the serious winter weather set in, and it's certainly quieter, a bit ticky but nothing I'd worry about. Now it's tucked up in it's winter quarters for the duration. Frustrating....

[Ducati Scotty]

I still suspect excessive cam gear lash on yours Will.

Scott

[2bikebill]

You may be right. I'll be checking it out after 500 miles...

[barenekd]

But tell us, Bare, which kind of witch powder do you inject into your oil pot?

It's got Mobil 1 VTwin in it. Should work. I thought I had some Marvel in the garage,but I can't find it. I've go to run down and get some.
Bare

[Arizoni]

My G5 is doing the compression release clatter when starting at temperatures in the 40's (F) but after a blip of the throttle it goes away.

I suspect it is because I'm running Mobil 1 VTwin 20-50 oil rather than a 15-50.

Thicker oil gets kinda gooey at low temperatures and something like that is all it takes for a little centrifugally operated part like the CR to want to stay where it is rather than to move at an idle speed like it is supposed to.

I am rather surprised to hear that Hitchcock removed the CR from WillW's bike.
That little part is a major part of the "Save the Sprag Clutch"  design on the UCE.

[singhg5]

I did not have this problem until this winter. Now on a cold morning, when I first start my G5 it produces 'ctuck' 'ctuck' valve noise.  I do not like this sound, so I give throttle a gentle blip and hold it for a few seconds and then let it idle at its own pace, as the sound goes away with slightly more throttle. There is no clatter sound rest of the day.

I think the oil is thick and gooey in the early morning and not enough pressure is built up in the hydraulic lifter. Perhaps a bit of SEAFOAM in the crankcase may clean & release sticky hydraulic lifters.    

[barenekd]

My G5 is doing the compression release clatter when starting at temperatures in the 40's (F) but after a blip of the throttle it goes away.

Usually that's the way mine works, too. But yesterday at about 45 degrees it started hten was slapping in and really going bonkers. I tried to rev it and it just quit. I had to recycle everything to restart it, then it was flooded so had to open the throttle to get it cleared out. It quit again. I went through that a couple more times before it finally kept running. It was fine after that.
I poured the Marvel Mystery oil in it, then hit the starter button. It started without even a clack. But it was in the 50s so warm enough not to go through the ritual. It obviously wasn't the MMO as I hadn't stirred it into in the witch's brew yet.  I ran it for a few minutes to get it stirred up though, so the AM may tell the tale.
Bare

[2bikebill]

Arizoni  -  it wasn't Hitchcocks, it was Watsonian Squire. It surprised me too, when they told me several months after the fact....   All they told me at the time was they'd replaced the sprag, which puzzled me as the sprag hadn't been faulty! Presumably they'd mis-diagnosed the clattering as the auto decomp, removed it, and fitted the newer more robust sprag to compensate. None of it had anything to do with what was wrong with the bike, and I'm just a little pissed off that I now have no auto decomp fitted. It makes kick starting really hard.

[t120rbullet]

I'm just a little pissed off that I now have no auto decomp fitted. It makes kick starting really hard.

1 # 570104 Fly Weight
1 # 570105 Pivot
1 # 570110 Pin  Assembly
1 # 570108 Torsion Spring
1 # 570416 Gasket, Cover
1 # 570293 O-Ring, Oil Pump Outlet

Right around $35 US and an hours work and you could become one with the kick starter again.
A gentle de-burring with a stone and those parts may not stick and clatter anymore too.
CJ

[Ducati Scotty]

Sink, I run 20w50 Mobil 1 too.