Rattle

[Greybeard]

I've just used some new petrol pipe like a stethoscope. Rattles are coming from the following areas: centre of the timing case, quite a lot of noise from the primary case directly over the clutch and some from the rocker box. However, the loudest knocking seems to be around the base of the cylinder block. This is worrying! As far as I know, slack big ends would go quiet under load and knock on over-run. My helmet, (LEAVE IT!) fits pretty tight so I cannot hear subtle engine changes. Drive side main bearing? Wouldn't that be more of a rumble?

I'm going to take the head off to check the valve guides. Should I heat the head to check for loose guides?

[berger]

I would put it in the oven and warm it up get a piece of brass and tap each one of them listening to the sound they make it should tell you a story

[RichardL]

I'd bet on Muscrat before I bet on myself (I know, I'm not alone), but wishful thinking might consider the adjuster that was too high being within a thou or two of hitting the cover. Things heat up and Bob is discovered to have no DNA in common with either of your parents.

Richard L.

Thumb typing = typos (sometimes corrected in the re-read).

[muskrat]

G'day Richard.
Yes that's what they usually sound like. Only happens when hot.
Cheers

[muskrat]

G'day GB.
Richards idea is easy checked with marks under the inspection covers.
Before removing anything. Get her hot and rattling again. Stop and remove tank and loosen the inspection cover screws. Start her again to get back to hot. Whip the plugs out and covers off and check the clearances.
To check guide fit I put head in oven at 200C for half an hour. then from the port side push on the guide with just finger pressure (wear a glove dummie). If it moves it's replaced. Guides come in oversizes of 2, 4 and 10 thou".
Cheers

[RDfella]

For a stethoscope you need a piece of wood, with the end grain to the bone under your ear. A piece of 1/2" dowelling is ideal. Nothing bigger. You are right - main bearing wear is characterised by a rumble and general roughness. Sorry, didn't notice - is this a CI or alloy head? If the former heating it won't make any difference to the valve guide fit.

[Greybeard]

...CI or alloy head? If the former heating it won't make any difference to the valve guide fit.

Iron head. Are you saying that the guides do not get any looser when the engine is hot?

[coater87]

 GB,

 After listening to the videos, here is my advise.

Its time for a peace of mind tare down. You are not going to be happy until you do, and you should not be- you have one of the nicest looking bikes on the site.

 If you are going to do the rebuild yourself, first move to make is throw away or forget the numbers for places like Draganfly and Feked. We are looking for precision internal engine components made to the correct size from the correct (or better) material.

 We are not looking for Wassell grade internal engine components here. And I know a few people will take exception to the Wassell/MCA argument, but we can always run a poll to get a consensus of which name people trust more. SRM or Wassell?.

 They cant make brackets or anything else that fits right for F*^%&* sake, are you really going to put one of their oil pumps in?

 Or send the whole thing to SRM to be gone through.

 Either way, I think I am hearing more than one rattle. I would stop running it before something possibly lets loose and you are worse off  than before. My ears are not that great, but one of the noises I hear is pretty solid if you know what I mean.

 Lee

[Greybeard]

Thanks Coater. Your advice makes a lot of sense. I was planning a long run this weekend but since I saw Musky's concern I'd already decided to cancel that run.

After I posted those video links and read Musky's comment I was set to start taking things apart but was feeling so depressed about it I shut the garage, ran a hot bath and read my book.

I am capable of engine work but the thought of handing the lump over to experts to sort out seemed very attractive.

I suppose I must gird my loins and take the darned thing to bits again.

[BigJim]

Hi GB, sorry to hear of your worries re rattle. If it's any consolation mine is much noisier cold and hot but worse hot too. An engineer i respect heard it and had no concerns at all. he races and tunes manx's and said if they don't make a racket they don't run (manx's that is). I used to have a little man with a hammer inside the centre of my timing case when hot, tapping away. removed drive for dynamo (belt not chain) and it was reduced. This means i'm aware of all the other clacks and bangs! I will be riding it for the DGR even if the bugger does go bang!!!
 

[RDfella]

GB - yes, C iron guides in an iron head will retain same fit when hot (they're the same coeff of expansion). Bronze guides in an iron head will tighten when hot for the same reason. CI guides in an alloy head will lose some tension, bronze guides in an alloy head less so. Same of course goes for seat inserts.

[berger]

I'm sticking to warming it all up and giving them a tap even though its cast iron a loose or coming loose one will be of a different sound

[Greybeard]

I'm sticking to warming it all up and giving them a tap even though its cast iron a loose or coming loose one will be of a different sound

I'll certainly be looking, (and listening) very closely at the guides.

[morris]

I doubt it to be the cam or a valve. It seems to me that the tapping sound can be heard each cranckshaft turn. If it where the cam or a valve it should he heard every other turn
Wild guess but could it be a piston hitting the flywheel? I know there's very little room (couple of thou at most) between the piston skirt bottom and the flywheel at BDC.
If I remember well you had some trouble with a little end bush for which you had an oversize bush made? If the piston sits a little lower than standard it may kiss the flywheel.

[Greybeard]

If I remember well you had some trouble with a little end bush for which you had an oversize bush made? If the piston sits a little lower than standard it may kiss the flywheel.

That is an interesting thought. I suppose when the engine gets hot the piston will be slightly longer so you may be correct. I felt most noise was at the cylinder base area so that might explain it. I cannot work on the bike until next week now. I'll let you know what I find. Thank you for pondering this problem and remembering that I had fitted an oversize little end bush.