Re Valving r100 gs

[MickDB1]

Hey up
I am contemplating re-valveing the 91PD - its at 70k km at moment
whats best - I was/am beleiving that airhead 100s need/require new exhaust valves at around 50,000 ml as they tend to dropum after this mileage
So
do I go and do all and every valve inc and all springs and collets stems etc and with standard BMW or the high temp Swis Motobins do dahs
Or should I just get a new exhaust valve and swap that till it all starts smoking and using oil -
just give it all a COLA and re-grind the seats and de-coke the heads
any tips will be helpfull
Anyone got a set of heads all done up for sale by any chance

 

[abrasion]

When i was thinking about doing this i spoke to motorworks.
They told me its not the valves that fail on their own but is caused by wear in the valve guides.
They just said check the top of the valve guides. if the colour around them is uniform they are ok. If there is a patch that is lighter the valve guide is worn and needs replacing.
Checked mine and both had wear in the guide. JustStans however look fine.

Easy enough job to get the guides replaced and seats cut.

 

[(RIP) Proff]

Exhaust valves, they tend to break the heads off after 40K miles..
It's said because valves are made in two parts and friction welded..
I've personally never had a problem with valve guides except for one working loose in 1979 on a R100s and starting to flare on the head of valve.......

IIRC the NEW valves have 3 angles to grind,, Rob knows better than me on that

 

[Kenny]

Worth getting them done at that mileage anyway

 

[cookie]

just the exhausts probably, but i think you'll find the guides will be too sloppy to re cut the seats, so you might as well do them and all.

you could get away with just grinding the new ones in, but why do half a job?

this bloke usually does mine. great work, but don't believe the delivery times

 

[(RIP) Arkwright]

A job for Mr Scriminger I would have thought possibly Mick,
You can always drop them with me and I'll take them up there.

 

[Sylvester]

Bugger, mines done around 90k kms so I guess mines due as well. It's not burning any oil either or making any noises so......bound to happen. Sod's law an all that. I'm gonna change the timming chain as well so may as well take the engine out and do it all indoors then. While I'm there I may as well.......oh no here we go again!!!!

 

[(RIP) pastyman]

I know ive posted this before but All I can say is to look at the K-line system of valve guide liners. This a cheaper and non damaging way of replacing your valve guides. The traditional way of removing the old guides is to knock them out which can damage the heads and of course you have to buy new guides. this system puts a phospher bronze liner into the existing guide which has lots of advantages and can easily be replaced time and again. I suggest you check out the K-Line website, all is explained there.
I had my berthas done a couple of years ago, it was much cheaper and I had them back within a couple of days. one noticable thing I have noticed is how clean the oil stays. After a couple of thousand miles the oil is still clean so nothing getting up the valve guides.

 

[Archie Adv]

CYL HEAD OVERHAUL

Hey up
I am contemplating re-valveing the 91PD - its at 70k km at moment
whats best - I was/am beleiving that airhead 100s need/require new exhaust valves at around 50,000 ml as they tend to dropum after this mileage
So
do I go and do all and every valve inc and all springs and collets stems etc and with standard BMW or the high temp Swis Motobins do dahs
Or should I just get a new exhaust valve and swap that till it all starts smoking and using oil -
just give it all a COLA and re-grind the seats and de-coke the heads
any tips will be helpfull
Anyone got a set of heads all done up for sale by any chance

Mick,

Take it to Scrimger Engineering...... they did the Bumble wasp you own and a damn good job they did too.

A

 

[Colt]

what sort of price is an overhaul by scrminger or cray?

 

[Archie Adv]

Scrimger

what sort of price is an overhaul by scrminger or cray?

Mick needs to nswerr that he has the receipt but I think about £180 inlcuding postage

 

[VAL. H.]

Tony, Have you got a web site address for K-line? This comes up on Google as some sort of container company

Ta Val.

I know ive posted this before but All I can say is to look at the K-line system of valve guide liners. This a cheaper and non damaging way of replacing your valve guides. The traditional way of removing the old guides is to knock them out which can damage the heads and of course you have to buy new guides. this system puts a phospher bronze liner into the existing guide which has lots of advantages and can easily be replaced time and again. I suggest you check out the K-Line website, all is explained there.
I had my berthas done a couple of years ago, it was much cheaper and I had them back within a couple of days. one noticable thing I have noticed is how clean the oil stays. After a couple of thousand miles the oil is still clean so nothing getting up the valve guides.

 

[cookie]

Tony, Have you got a web site address for K-line? This comes up on Google as some sort of container company

Ta Val.

cylinder head shop do them. i've had a few fitted, and been pleased with the results.

 

[bernardofeio]

“Exhaust valves, they tend to break the heads off after 40K miles..”!!!!!!

My r100GS has 140 000kms… I’m just lucky? Since I’m replacing the piston rings should I also change valves?

 

[Kenny]

Wonder there's any valve left in there

I've heard of many MANY airheads with very high mileage valves in them and no problems at all........it is however, the 'going rate' to replace them at about 50,000 miles ( internet folklore perhaps playing some part here? ) and I would certainly be replacing yours whilst cylinders are pulled down. Be like a new bike with rings/valves done

 

[bernardofeio]

What’s the diameter of the valves? Should the guides also be changed?

 

[cookie]

Should the guides also be changed?

yes, if the valves are a loose fit in the guides.


ps. they probably will be.

 

[(RIP) pastyman]

Tony, Have you got a web site address for K-line? This comes up on Google as some sort of container company

Ta Val.

Yes, try k-line valves, that should do it.

 

[(RIP) Proff]

http://www.cylinderheadshop.co.uk/K-line.html