Cold rattle

[bazzyj]

Hi all well here we go,
I am totally peed off now with this rattle come knocky noise when cold.
The bike was perfect when i bought it 20k 1996, no noises running perfect no probs, after about six months a rattle appeared as over night, a little like piston slap, oil was ok and bike still ran perfect. Off came head and barrel and new piston and rebore carried out, valves relapped new gaskets installed, all back together and doh rattle still there. Off with rocker cover and noticed play in decompressor( really sloppy on camshaft but with no signs of wear) replaced complete decompressor assembly,new decompressor sloppy so i guess this is normal, re assembled, tappets adjusted, new oil and fired her up, aaaaaaaaahhhhhhhhhhh, rattle still there. this noise is really loud when cold but can come and go sometimes, the bike runs perfect, but noise will increase with engine refs and decrease when throttle off, as engine gets warmer noise decreases and when hot no rattle evident, the parts for these bikes can be expensive, so reluctant to change things for the sake of it. I am a motor technician by trade so i am quite acute to these noises, however i cannot pin point the noise to anything direct, by using screwdriver and ear. this is definatley engine noise. i see from other threads other users have the same concern, some say timing chain, but believe me ,if it was this, the thing would be hanging off the noise it can make, i am at my end of tether and i am currently going to run it to whatever it is breaks, by the way the bike runs perfect all the time? whilst apart the rocker, cam valves seem perfect, plenty of oil getting up there as well, i am totally baffled and apart from changing everything top end, which would be expensive i know not of what it could be, any help would be appreciated sounds like a diesel and getting worse, takes longer now to dissapear even when warm

Thanks baz

[catteeclan]

Long story short, I got a xl600lm with a buggered engine. Rebuilt it with a new crank, oil pump, cam and followers, gaskets piston n rings, piston pin. All genuine stuff. Plus a rebore out to max oversize. Put it all together and all was well untill I gave it an oil change after a couple of hundred miles and found metal in the oil. Stripped it down again to find a couple of gears (gearbox) breaking up. Whole S/H gearbox fitted with non gen gasket set and guess what noise I have. It's been like that for 2 years now but I'm going in again soon.
When I rebuilt it the first time we took the bore out as far as we dare but there was still a few scores as the last owner had rode it till it stopped with no oil in it. So I always wanted to do that again.
My noise has got to be down to;
Piston slap, unlikely as it was fine before the second rebuild.
oil pump, it is possible as I stripped it and cleaned out. Could I have assembled some part wrong?. Also unlikely coz it's still going.
Non gen gaskets, still unlikely but possile as the head and base gaskets were thinner than the genuine ones they replaced. Piston making slight contact with the head? Is that sort of sound on mine.
Should see that after getting the head off.
Going to get an oil pressure gauge on it before stripping down again.

Good job I kept it short.

[ste]

Hi Bazzyj,

When you next have the rocker cover off run a thumbnail over the cams and check for any lips on the edges of the cams or use a straight edge. I bet you'll find some wear on one or two of them; also you should check the corresponding rockers, as you probably know these should be convex and smooth with no wear present also.

I had to replace the top end of one of my Domies and this noise was driving me mental until I noticed the slight wear on the cams. Once I replaced the cam shaft, bearings and rockers the engine is now running perfect and no annoying rattle!

I know that a new cam shaft is expensive but you will be taking a chance with a second hand one - I would check first to see if there is any wear!

Hope this helps.

Ste

[catteeclan]

Any news yet?