Valve wear question

[Cakeboy]

Looks like my '57 G3LS has had a spring conversion to coils a while back, and as far as I can gather from searching old posts, this uses the same valves and guides but can anyone confirm that?

I want to know because I think there's too much play in the guides so will probably invest in new guides and valves whilst it's in bits. I seem to remember seeing a post on how to measure valve guide wear, but no luck after much searching. Can anyone advise?

Thanks.

[Rob Harknett]

As you have asked this question, I would say do not change the valves and guides. The bikes is probably good for many years of summer pleasure riding runs.
Why invite problems by practising how to do a job, that probably does not need doing. In over 60 years I have never changed a valve guide. The first G3 L/S I got in 1956
had done over 100,000 miles when I sold it in 1962. Back then fuel made a lot of carbon, I only ever cleaned valves and cleaned up seats a bit grinding.

[Mick D]

Hi

I'm with Rob on this one , these bikes are agricultural to say the least. Have you ridden it yet, does the engine emit oil smoke or foul the plug?

Changing the valve guides could damage the head, why take the chance unless you have to? Don't forget you will have to re-cut the valve seats too, do you have the tooling / experience to do this?

My advice would be to strip the bike down completely for inspection, (don't remove interference fit components, bearings / bushes etc. or split the flywheels.) unless necessary for replacement / repair. Replace / repair broken and worn out components, rectify previous owner bodges, cosmetically restore to suit your taste. Get riding, short journeys at first to confirm the magneto and dynamo are reliable and to fine tune timing and carburation.

Regards Mick

[Cakeboy]

Thanks for the advice chaps, I didn't want to change them, just thought I ought to so you've made my mind up. Cheers.


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[mdt-son]

I want to know because I think there's too much play in the guides so will probably invest in new guides and valves whilst it's in bits.

Maybe your valves and guides are worn? We don't know that. I recommend taking your cylinder head to an engine renovation workshop to have a second opinion, if possible.

As for removing guides without damaging the cylinder head, you need to preheat the head to about 300 degrees C. Using a suitable drift, the guiides will come out easily with no scoring of the head.
Damage to the head occurs if you hammer out the guides at room temperature.
Valve seats need to be cut using the appropriate conus cutter. There is no shame in entrusting a reputable workshop with these tasks.

-Knut

[Rob Harknett]

Tolerances can be found here. http://archives.jampot.dk/book/Workshop ... ndards.pdf
NOTE.
I have never known of a bike that has been running OK, braking down due to valve, guides or valve seats.
I have known of many that have broken down having been repaired??? by the inexperienced. Valves seizing, guides coming loose, also guides not fitted in the correct position, plus valve seats coming loose and turning. Hence my leave well alone attitude.

[56G80S]

+1 for Rob's comment. I had done this, correctly, but made the mistake during a stripdown for another reason of taking the head to a reputable(!!!!) company who stuffed things up spectacularly.

Johnny B