valve clearance checks ?

[straycatuk]

Firstly,HELLO to all . I'm in the UK and have recently purchased a 1980 GS550 ET .I owned one for a couple of years back in the mid eighties followed by a GS1000 which I had for over 10 years . Always been my favourite bikes,but this one has "problems" which I won't go into here,but I'm looking for advice on valve clearances ;

My manual gives 2 positions to check clearances 1 with cam lobe at 12 oclock from head and 1 with it at 90 deg. to head ,but these seem to give different measurments. Is there a prefered way to do this?

If I have a gap of 0.03 or 0.04 should I go a shim size smaller and risk a slighty bigger gap than the max. (0.08) as I presume that the gaps gradually close up and it's better to be bigger than risk them closing up and not allowing valves to seat.
Has anyone got this problem nailed?

the bike has done 35000 miles.

thanks

DAVE -straycatuk

[tkent02]

Each position of the crank results in two checks, each valve is to be checked in only one position. Read the manual carefully. The other possible positions move the cam up or down within it's cap so the readings are inaccurate.
And looser is safe, they do usually wear tighter.
Welcome to the GSR, Basscliff will do this part better.

[straycatuk]

thanks for the info. I think the diagram in the Haynes manual is confusing:shock:.
Yes I'll gap them towards the bigger size as 0.04 is getting pretty tight.

[TheCafeKid]

Agreed, looser is safe to a point. I have read some info from a friend who consulted an old race bike builder, who said that, for the street, up to .10-.11 ish is even ok. I personally have acouple in the .09 range myself, and dont worry a bit about it.

[tomo]

Like the other guys said, go for the slightly bigger gap. An old guy I know who has ridden bikes for over 60 years (& used to race em), told me that when I got my first bike. His philosophy was that a slight tappet train rattle was good, and that a quiet engine indicates the gaps being too tight.

[straycatuk]

Just finished replacing the cam cover. All clearances where out of spec. Managed to swap a lot around and only had to buy 2 new shims. Smallest gap is 0.05 and most are now in the 0.06-0.07 range. I won't do more than a couple of thousand miles before I check them again....if I ever get it running !