Severe Knocking - A10 Road Rocket

[Brucie64]

Hi All,

OK, finally yesterday after finding nothing glaringly obvious I decided to re-assemble the engine making sure everything is good and tight (primary chain and engine sprocket especially). I will start the bike again today and let you know if it is still clonking or not. If it is then I can only assume I will need to split the crank cases for a deeper look. One thing I did find yesterday however was the idler pinion on the timing side (the one that holds the dynamo gear) has a lot of end float. With the dynamo gear attached and fastened down I can still wiggle the dynamo gear back and forth quite a bit. Should there be appreciable end play here?, I would have thought not once the inner timing cover had been fitted but simply don't know.

Again any help would be greatly appreciated guys.

Regards
Brucie

[duTch]

 Good luck- from memory, I have about 20thou float on the idler, but far as I can tell, the only lateral influence on it is from my dynamo belt alignment, I figured it best to allow it to find it's own happy place.... which reminds me...

 Two things,
 1) I've been meaning to mention this for a while, but. ..make sure your oil pump mount screws are tight, when I was in mine to check the belt, I noticed they were a bit 'loose'... , but are  allen screws- I have to remember to order some proper studs with lock-nuts...reason for lock-nuts, is so that they can be backed off then nipped up to remove the stud, and on replacement screw the stud in to the full extent of the coarse thread, and use the fine thread(carefully) to make it nice and snug, and fine threads are less likely to vibrate loose. As these are some of the most crucial fastenings on the bike, it's worth getting right- note to self

 2) forget it- I did...I think it was a personal thing....

[Brucie64]

Thanks fro your input again DuTch,

Just read an earlier article on this site reference the idler pinion, it mentioned something about a cork washer should be fitted to the idler before re-assembling the inner timing cover. Obviously I knew about the camshaft/breather cork washer but a cork washer on the idler?, there definitely wasn't one on when I took it apart and don't recall seeing any mention or requirement to fit a cork washer to the idler in my Haynes manual. Should there be one?

Regards
Brucie

[bsa-bill]

Yes, goes on before the dynamo drive sprocket

[duTch]

camshaft/breather cork washer but a cork washer on the idler?

Yes, goes on before the dynamo drive sprocket

...oh yeah...didn't wanna complicate things...I couldn't make any of that work, so it's still in the packet for a bored Nonday...

[bsa-bill]

sometimes there does not seem enough room for the cork, I had this on my last rebuild, the idler pinion  is a (should be) tight fit on its shaft, I had a look to determine how much play there was and pushed the pinion back on the shaft a tad, then I could get the cork washer on, my mate took a different approach and  cut the cork washer in half, I like my fingers too much to try that

[Brucie64]

Ok, the saga continues, idler gear cork washer on, result no end float  . All cases back on, primary chain adjusted, double check all everything was nice and tight...before attempting to start the engine.

Engine started first kick (its never done that before).....result series metallic clonking from engine....hit the kill switch pretty mad smartly. I am now thinking it may be emanating from the barrels or head area. Sorry couldn't afford to leave it running whilst I videoed it just in case it failed altogether. One thing I have noticed though is that one exhaust pipe has discoloured more than the other, not sure if its a red-herring  or a pointer towards the fault.

Either way going to have to start stripping the top half down now.

Regards
Brucie

[bsa-bill]

Well now I do like the copper rocker oil feed all buffed up, mine looks like that but not on the bike at the moment  plus the copper pipe has a few too many twists in it, anyone know what size that pipe is, I'd like to make a new one (two really).
hi-lacking your post a bit Brucie , no ex pipe fins?, also how close are the pipes where they cross (no touching and banging together?
interesting magneto cover? a bike with character that for sure
well hope you find something in the head area but not too much of a biggie - keep us posted

[Brucie64]

Hi Bsa-Bill,

No fins mate, I have a set of 57 spitfire exhaust pipes in the garage ( the ones that went underneath the engine) but as they are tatty I thought a couple of years ago I would get a set of the pipes that went alongside the left hand side of the frame. Only problem was they didn't fit into the exhaust ports properly, I needed to cut a section out of one pipe to make them fit. Only problem was the cut was close to the bend in the pipe resulting in not enough room to fit fins.

Ok back to my clonking, I think I might have found my first problem. I have just lifted the rockerbox off and noticed the RH inlet pushrod "endcap" is loose. You can move it in and out of the pushrod by at last 1.5mm (sorry no idea what that is in feet and inches), it will spin around on the pushrod itself but it won't actually come away fully. None of the other pushrods ends are loose so can only assume this is a fault, just wondering of this could be one or indeed "the" source of my noise?



Regards
Brucie

[Brucie64]

Hi Guys,

This noisy Norton sounds like exactly the same problem as I have on my bike.

https://www.youtube.com/watch?v=9sJyxm-CHok

Regards
Bruce

[RichardL]

Brucie,

I doubt it is the loose pushrod end. Its movement would be limited to and no noisier than valve clearance. The localization of the Norton noise does appear to be from the rocker area. It is so distinct and clicking that one might think it's a valve adjuster hitting the cap. Anyway, just rattling on (so to speak), other possibilities I would want to eliminate before splitting cases include: sticking valve that might be getting just kissed by the piston to release; pushrod on the lip of the lifter (leading to the aforementioned valve adjuster hitting the cap, but I don't know if this can happen with Nortons); thrashed gudgeon-pin bearing; broken valve spring.

OK, I'm probably going back to the Norton video again to "see" if  I hear anything else. I'll edit if I have other ideas, potentially, each stupider than the last.

Edit: Regardless of the apparent localization, there is enough similarity between the noises in my video and the Norton to still suspect the rod journal bearing. I honestly hope that is not what's happening in your  case (or cases), but it would require way more zen chi than I have to not take some satisfaction from a correct guess. Apologies, in advance.

Richard L.

[edboy]

that norton noise could be many things originating from the valve gear and cylinder head it sounds to me a double tap on a valve. a10 s can break the pushrod in and ex shafts. a bent valve, broken valve spring or sticking cam follower? or something wrongly assembled. you really need to put the whole engine on a bench and turn it over and spin it without the plugs in. what has caught me out before is too long front chaincase screws touching the crank and it could be something simple like that. in my case the screw was softer than the crankshaft ,eventually wore down and successfully ran the engine in.

[muskrat]

G'day Brucie. That pushrod wouldn't help the situation. But I think you'll at least have to lift the lid to check the valves, springs and guides.
Rotate the crank till the piston is on the down stroke and rock the shaft back and forth. Any noise or momentary lack of piston movement will indicate big ends.
Cheers

[chaterlea25]

Hi Brucie,
Have you taken off the sump plate to see if there is any metallic debris there?
If there is it may offer some clues to the problem(s)
John

[trevinoz]

That's what I said a few days ago. Have a look at the big ends.