tappet noise when hot

[emilios]

Hi
I just rebuild a friends plunger A10..
The engine sounds nice and quiet when cold but after is get little hot it has tappet noise..
I checked the tappets and was little open..so i set them again at 10thou both...
But after a couple of runs we have the same problem..
Did anyone had the same problem?
Thanks

[a101960]

Emilios,

I had this problem and the cause was a loose valve guide. The symptom was exactly as you describe. The engine would sound nice and quite when cold and as it warmed up it sounded as though a tappet was loose. I adjusted the tappets several times and the same thing happened every time. I would start the engine and it would sound quite until it was warm. Another clue is to look for oil being burnt. If the valve guide is loose oil will get into the comustion chamber. A loose valve guide will not always be noticed when the head is removed because the head will be cold and with a cold head the guide will seem to be OK. However if you warm the head up enough the guide will become loose.

John

[emilios]

Hi
John
 
Well i hope that is only the tappets and they need adjustment
cause if the problem is like u descript i have to take off the head again..
I will check the plugs for burnt oil but i didnt notice white smoke from exsaust..

[muskrat]

 G'day Emilios,
                   ditto to what John says. I'd put money on it, and usually the exhaust. Drop the pipes off and see if the port is oily.
Cheers

[emilios]

OK
So if we have a loose valve guide here would it be ok if the bike make a 60 or 70miles trip before i take of the head?
Regards

[a101960]

So if we have a loose valve guide here would it be ok if the bike make a 60 or 70miles trip before i take of the head?

Emilios,

I cannot make a definative statement about whether that would be a safe or acceptable thing to do. What I can tell you is that I rode my bike for quite a while with this problem before I actually found out that the guide was loose. What I can also tell you is that other than the tappet noise I did not notice any adverse effect. The engine started just fine and it also ran just fine. when I removed the head the piston crown was very black and oily, and so was the head on the cylinder with the loose guide. I have very little mechanical ability and so I sent my cylinder head to a specialist cylinder head reconditioner to have it repaired. I believe that you are a skilled engineer so the remedial work will probably be well within your capabilities. What you will have to do is to source an over size valve guide and bore the head to suit the oversize guide. As a matter of interest this problem of loose guides is not very common in iron heads, but it is very common in aluminium heads.

John

[emilios]

Thanks John and Muskrat  for your advices