Noise from top of rear cylinder?

[futter]

There is a bit of a noise from the top of the rear cyclinder.

It lessens as the engine gets hot, i.e. within a minute or two.

Am I right in guessing at worn cam bearings/set up? Or could it be a worn valve guide? Not too sure how these things work.

Not too worried as I have my old engine and that was quiet as a mouse.

[Huib Holland]

Hi Futter,

Describe the noise, noise comes in many ways! Is it ticking or more like a rattle. And does it get louder when you rev a little?

Greetz.

[futter]

Hi Futter,

Describe the noise, noise comes in many ways! Is it ticking or more like a rattle. And does it get louder when you rev a little?

Greetz.

More of a hollow tapping and it gets quieter as the engine warms but never quite goes. At that point it sounds like a badly adjusted tappet.

I don't have an exhaust gasket in at the mo - could it be that?

[anton88]

could well be lack of exhaust gasket - metal parts heating up and partly sealing the joints ?

[Huib Holland]

Try to determine where the noise is coming from. Take a long screwdriver and put it to your ear. It's a bit difficult cause it might sound it's coming from the whole engine. It's a bit less difficult when you can get your hands on a engineers stethoscope.

You could also trie to determine the frequencie compared to the revolutions. The 4-stroke does 1 combustion every 2 revs. A v-twin got two cilinders so 1 combustion 1 rev. If your big-end is shot and your revs are 1200 a minute it should be tapping 1200/60= 20 Hz.

If one exhaust would be leaking (what you can tell by holding a piece of paper around the exhaust) it would be 10 Hz.

For the tappets you should remove the rocker cover and inspect them. Check the camchain tensioner wile you're there

[futter]

Try to determine where the noise is coming from. Take a long screwdriver and put it to your ear. It's a bit difficult cause it might sound it's coming from the whole engine. It's a bit less difficult when you can get your hands on a engineers stethoscope.

You could also trie to determine the frequencie compared to the revolutions. The 4-stroke does 1 combustion every 2 revs. A v-twin got two cilinders so 1 combustion 1 rev. If your big-end is shot and your revs are 1200 a minute it should be tapping 1200/60= 20 Hz.

If one exhaust would be leaking (what you can tell by holding a piece of paper around the exhaust) it would be 10 Hz.

For the tappets you should remove the rocker cover and inspect them. Check the camchain tensioner wile you're there

Tried the screwdriver trick - not sure - defo from the rear half of the rear cylinder - makes me think of worn cam lobes???? on the exhaust valve, possible bearings on the cam???

I do have a doctors stethoscope (well the wife does) so might have a go with that.

Tried the bit of paper thing as well but the pipe gets so damn hot so quickly not too sure.

Thinking about it - it kind of sounds like the autodecompresor noise on my old XR600, y'know, when it re compresses??

Not to sure about the hz thing - all I know is that it doesn't really affect the running of the bike, although it does pop and bang a bit since I have put this engine in.

[anton88]

poppin and banging does sound more like exhaust leak thats the bit id fix first.

[futter]

poppin and banging does sound more like exhaust leak thats the bit id fix first.

Good point that Watson - thing is ...... I do have a set of exhaust gaskets for the bike, yet when I put the new engine in there wasw, in the rear exhaust port, where the pipe goes an small protrusion on the casing preventing the gasket going in - so i didn't use 'em!

I know - muppet!

Still, it'll give the wife another excuse to shout at me!

[anton88]

Still, it'll give the wife another excuse to shout at me!

ive got used to that now - just say yes dear and then she locks the back door so i can work in peace (tho it does get cold at times)

[futter]

ive got used to that now - just say yes dear and then she locks the back door so i can work in peace (tho it does get cold at times)

Yeah but she is being really mean this time - told me to sell the house and leave so she could get on with her life cos she hates me, I'm useless, lazy, yada yada yada .... told me I never listened, only wated sex whenb I felt like it ...

I told her to shut up, put the kettle on and prepare for some rumpy pumpy!

It doesn't matter that over the last few weekends I have:

Built her a pergola
built her 4 7'x3' planters
Collected a ton of compost
Dug out the front garden
Cleaned out the pond
Decorated one of the bedrooms

I am a bloke therefore I cannot win!