Topic: glad this happened at home...

[hymodyne]

morning all,

last evening while working through the issues I've been posting about since I got the bike plated, I noticed a clicking sound around the #4 Intake/exaust area. when I opened it up, I discovered an intake valve missing, and two springs (inner and outer) shattered into about a dozen or so pieces. valve seems to have been sent spring free down the valve guide into the combustion chamber.

question:

should this event make me skeptical about the rest of the springs?

in an earlier post, I spoke of having spark and fuel but varied degrees of combustion in the #4 cylinder. would a valve spring on its way out have this effect?

I need to find a reasonably priced valve tool. my local auto parts store is just that, an auto parts store. thread chasers, compression testers and valve removal tools are for cars only...

hym

[hymodyne]

an update:

intake valve bottomed out on piston. a few marks but no dings or cracks. the valve itself if difficult to me in the valve guide, I'm assuming its bent. I have the original head for this engine which was removed for one or more bent valves. should I search the head I have for a useable intake valve, or replace with a new one?

hym

[TwoTired]

Great, you have spares!

I would certainly use any valves on your spare head that will move properly in the valve guide and will fit onto the seats properly.  The seat fit can be checked with a Dye and a bit of lapping compound.  Dye the contact surfaces, (I've used Dye-Chem Blue) put a thin coat of lapping compound on the valve seat, insert the valve and rotate the valve.  A bent valve will only wear on one side and should be discarded.  However, if only a very small area still has die on it, you may be able to lap the valve to make full contact and reuse the valve.
The other concern is if the bent valve damaged the valve guide and made the hole oblong.  With the valve sligtly open, try to rock it back & forth in every direction.  If there is more movement in one or more directions than others, you'll need a new valve guide, too.  If the overall wobble is more than on other intake valve positions, then you will need a new valve guide, for that reason, too.  I would check the valve wobble with a dial indicator.  But, I don't know offhand what the usefull  limits are.

Probably someone else can post that info.

Good Luck!

[bryanj]

If you need a guide it has to be new as they are reamed after fitting and never transfer "straight". Not sure what bike it is but www.davidsilverspares.co.uk carries NOS or pattern valves for most fours and springs. Personally if one has gone i would change the set