SOHC.co.uk Forums > CB500/550
Valve stem seals
JustcallmeMrT:
Job done. Thanks folks!
bomber:
Sorry for hijacking thread,
Does head need to be assembled to check valves with petrol?
I'm asking as it takes time to put springs and so on, but you need them to hold seal right?
Thanks
--- Quote from: Oddjob on February 13, 2015, 01:51:33 AM ---Did you remember to tap the top of the springs with a hammer, makes sure the collets are engaged.
I also used to fill the tracts with petrol, if you can see any seepage past the valve seat you've not lapped them enough. Petrol seems to be very effective at finding any imperfections in that area.
--- End quote ---
AshimotoK0:
--- Quote from: Oddjob on February 14, 2015, 05:41:19 AM ---I used to test mine by using a tap wrench, tap as in tap and die set not the kitchen tap :) I used the chuck type tap wrench, I'd insert the valve with some grinding paste on the seat and then attach the tap wrench to the stem, I found that this way I could pull the valve onto the seat much better than using a good damn awful sucker on a stick. When I wanted to test with petrol I'd just pull hard on the tap wrench, probably less pressure than the springs so if it didn't leak then it was unlikely to leak with the springs on. Similarly I could test the valve seats before removing the springs to see which ones were leaking, if you watch the valve head you can spot the petrol vapour coming out if it was a slight leak or dripping out if the seat was badly burned.
--- End quote ---
I do the same but with a Jacobs type chuck from a drill. Also use a g clamp witha U shaped bent bit of metal for a valve spring compressor. Soundinga bit 10/- (10 bob) readers tips from MCM circa 1968!
JustcallmeMrT:
I did check the valves were sealing - all good, no leaks.
bomber:
Thanks for tips!
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