cylinder valve guide removal bsa 350sv l29

[robbsa]

hi all,

more advice needed!! i feel its better to ask then risk damaging something through ignorance! i need to replace one of the valve spring cups and clean one up, therefore i think i need to remove the guides.

they look like they would press out from the top (by pressing a rod through the valve cap onto the top). can anyone confirm before i start?

i've attached a photo, but not sure if you will be able to make it out from the image.

Thanks,

rob

[chaterlea25]

Hi Rob,
Remove the valve caps, valve and springs,
Have a stepped drift turned up from some brass or copper that will fit snugly inside the guide and the larger diamater a little less than the guide outer size!
If there is much carbon on the port side of the guide, (exh)  remove it or have the area blast cleaned
Heat the barrel to maybe 150c and then the guide should tap out !!
Very often they will split and new ones will be required (probably needed anyway??)

HTH
John O R

[robbsa]

thanks john, i will turn some up tomorrow!

[33d6]

As both the VMCC Library and BMS books have a selection of L29 literature, spare parts lists, maintenance hints & tips , etc, I suggest that you get copies. You will have a much better idea on how to go about things.

An illustrated spare parts list is remarkably useful as you get a much better idea on how bits fit together, and a factory issued hints & tips booklet on your particular bike can only make life easier.

One last thing, make your new valve guides out of cast iron alone. Do NOT use bronze. Bronze works well in some applications but always needs lubrication. It is not suitable for this application. Valve guide lubrication on vintage sidevalves was always marginal - and thats being polite. After years of trying all sorts of methods to get lubricant in there I found by far the best answer to be a smear of silicone grease on the valve stem on assembly. This is one application where silicone grease really stands out. Be careful with it as it is beast to get off paintwork and the like. Its  good in its place but an absolute stinker elsewhere.

Cheers,

[cardan]

Check they're not screwed in before you hit anything!

Leon

[robbsa]

Thanks 33d6, that sounds like a good tip with the guides. I have a parts catalogue for the bike Which is really useful, and from the picture of the valve guides it did look like they push out. I was just reassuring myself. I have been in contact with the vmcc but wasn't aware of a hits and tips publication so I will do some further digging! thanks again for your suggestions,

Rob

[robbsa]

so, i turned up a stepped drift and knocked out one guide with relative ease. the other is a bit more stubborn so i heated up to 150 degrees in the oven as dont have a torch to hand tonight. made the kitchen smell pretty good! gave it as much tapping force as i dare but still not budging. I tried freezing the drift, but dont think the freezer got it cold enough, so i will try with some freezer spray on the guide tomorrow.

if this fails i might try and bore it out and repeat the process. to make the guide shrink faster. i dont want to bore it to the outer diameter of the guide because i might end up damaging the cylinder. anyone think this is a bad idea before i proceed?

you are all being very helpful, i hope my repeated posts are not getting on anyones nerves!
Rob

[R]

I'm sure we are all learning something for folks asking interesting and technical questions, keep asking away.

[33d6]

You don't say which guide came out easily, inlet or exhaust.
My experience is that the exhaust is usually the grumpy one because the inner end it is covered in muck. That has to be dealt with before anything happens.  Sometimes it is easier to tap it upwards to start it off. I have also seen stepped guides installed so it will only come out the one way. Also check no bright spark has pinned it somehow.
The joy of an 80 year old engine is that there has been time for all sorts of mysterious bodgeries to be inflicted on the poor thing. Sometimes you have to think like an archaelogist, not a restorer.
Boring is an absolute last resort. Once you know how it was installed you can reverse the process.
Cheers,