.002"/.05mm valve specs; too tight?

[Flynn]

My valves were loose last time I adjusted them so this time along with checking my rocker arm bearing welding (holding up just fine) I figured I would adjust the valves on the tighter side of things.

I adjusted them with the feeler gauge between the tappet and the valve to a tight fit and then slid it out and back into check it.

As soon as I started the bike there was a metal knocking on metal sound. I figured this was the sound of the cam lobe on the relatively dry rocker arm bearing so I let the engine idle but it was still there.

After idling for about 30 seconds there was smoke and a metal burning smell so I shut the motor off immediately. I figure the valve lash might have been too tight and the valve might have burnt as a result.

Although this doesn't make sense because I was very careful to set the clearance accurately.

I have since pulled the valve cover again and everything was all present and correct, nothing was damaged (phew!).

I am going to set the exhaust valves to .024"/.06mm tomorrow and try that, since it is the exhaust valves that are at risk of burning.

Anyone had a similar experience with the valve lash? I think it was the 90s model that had a clearance of .1mm which is twice of the newer ones.

 

[RDTCU]

Valve clearances get smaller as the valves heat up, and clearances also generally gets smaller with wear, as the valve seat will wear quicker than the cam, rocker or valve.

Too loose gets you a little noise.
Too tight gets you a little or a lot of noise, excess wear, and shorter valve adjustment intervals.

There's a reason they spec the clearances they do, to account for the valves growing at higher temps.
A small clearance at room temp could be zero or negative at operating temp, which could explain your experience. Did you set the crank to TDC?

 

[Flynn]

Thanks for a speedy reply RDTCU.


Right, here's the deal, I've been busy in the garage and reached a conclusion.



It turns out it was actually just a dry top end. I fitted the oil filter the wrong way around:



Fail! When it is this way around the metal base of the oil filter is nearly blocking off the oil hole in the filter housing.


I was lucky I was paying attention and smelled the burning and saw the smoke before the camshaft and rocker arm bearings were toasted.


Although I did pull the banjo bolt afterwards it looked as though some oil did get through so it wasn't totally dry. When I pulled the rocker cover the camshaft lobes and rocker arm bearings were fine.

Additionally, the motor had been sitting for the last three weeks before starting it whilst I was waiting for the quite frankly useless dealers to source an oil pump gasket for me.


This was what it sounded like even after putting the oil filter in the correct way:


You can hear each time the cam lobe pushes on the rocker arm bearing, not pretty.


The first time when I thought I had burnt an exhaust valve it sounded even worse! This time around with a fully working oil supply I let the motor run and sure enough after a minute or two the noise disappeared. Only then could I hear how badly the valves were ticking!


Here's what it sounds like now after a couple minutes of idling:


So I hadn't adjusted them too tight after all, I adjusted them this time to a tight .008mm (three thou) to be on the safe side, but now I've gotta go back to quieten the buggers down. I am still undecided whether to go for a tight .006mm/2.4 thou or a loose .005mm/2 thou, I don't want to set them too tight and have them tighten up on me in a few hundred miles and burn the exhaust valves.



Anyway it's not an exact science using feeler gauges, I am not sure how much resistance should be felt.


The very obvious dry sound of the top end was unexpected. Referring back to where I ran the motor with about a half litre (two quarts) of oil, I don't remember hearing any sounds like this at all and that was running for about 5 minutes. Mind you it had been ran several times before hand and not sat for three weeks so perhaps the top end was drenched enough to last with minimal oil circulation.


So yeah, nothing weird had happened as a result of adjusting the valves after all, it was perhaps the combination of the oil filter being the wrong way around and the engine being sat for awhile that was the problem.

Or I just didn't let it run for long enough because the oil filter being the wrong way meant that the pressure in the filter housing was high and the oil was squirting out and thus I didn't wanna keep it on.

Also am I right in thinking that as long as the engine is on the compression stroke then it does not need to be at top dead centre to adjust the valves? As both intake and exhaust valves would have to be closed on the compression stroke to keep compression anyway.

Also normally I would prelube components but this time I forgot. These engines are not as fragile as the DR650 boys would have you think

 

[Flynn]

As it turns out, it seems that I made the unusual mistake of adjusting the valves on the wrong stroke as there was no lash at all on the compression stroke. Strange as I used the timing mark and I knew that there were two TDCs, exhaust and compression. Anyway when riding the bike as in the above videos it felt very flat and there was no power.

Today I adjusted them to .002/.024 inches (.005-.006mm) and the loose lash sound is back (that was the reason for adjusting the valves in the first place) as well as the power which makes me think that it could be a slack cam chain rather than loose valves as I doubt less than half a thou/.001 of a millimetre is enough to cause such loud lash.

Here is what it sounds like after my latest adjustment



Despite how it sounds it is running sweetly right through the rev range.

 

[mjskier]

There is a large spring that pushes the oil filter in (between the cover and the oil filter)
Did you lose it when you installed the filter backward?

 

[Flynn]

No it's okay thanks it stayed put and the noise was the cam chain. See my "610 cam chain rattle" thread for details.