Topic: Replacing valve guide seals?????????????

[cappy]

Hello,

I am currently rebuilding a CB550 engine for my cafe project bike.  The bike orignally had 8500 miles on it.  1977.  I have purchased a complete gasket kit that includes the valve guide o-rings.  Should I try to damage my guides by banging them out to replace the seals?  I have read that these seals can leak on the exhuast side.

What is the best method on removing the guides?   I assume they are hardened, so banging on them probably would not be wise.  I have seen then special tool in the manual but what else could be used?  Arbor press?

Thanks in advance,
Getting ready to get out of the driveway,
Greg.

[rhinoracer]

Based on the premise that nothing goes as planned, if they're not leaking and you don't plan to do a valve job don't mess with the guides, at the least you'll have to lap the valves and seats.

On the other hand if you're doing a full rebuild why not freshen the head also?

[wardmoto]

I am slightly confused...are you replacing the seals or the guides or both???  The seals will pull off the top of the guides, and the new ones press back on with your fingers and a bit of oil.  The guides are pressed in the head and will require help and $ to get old ones out and new ones in.  While the head is off, take the split keeper off the valve stem and remove the retainers and springs.  Slide the valve away from the head and its seat about a 1/4 inch...try to move the valve in any direction that forms a radius from the valves center while looking at the combustion chamber side of the head.  It shouldn't wiggle much if at all.  If it doesn't, leave the guides and your money alone.  If you have things apart it is silly not to do a quick valve seat lap and put the new seals on at least .  Also, make sure all the valves and their parts go back to their respective homes...#3 exhaust valve likes where he came from and would like to go back there when you are done...it makes a difference.

[cappy]

Thanks for the feedback.  The bike has 8500 miles on it.  The only real reason I tore the top off was to replace the o-rings for the oil transfer to the cam.

My co-worker (Harley man) said leave them alone.  Pressing out guides is opening a can of worms.  He claimed I would have trouble getting the guide in square with the valve seat.

I have planned on lapping the valves with NAPA valve grinding compound.  Any tips on doing that? 

Thanks, I think I'l going to leave the guides and money alone.

Greg.

[holysmokes]

when relapping your valve seats, a light clean lap is your desired product

I use a medium grind paste

be sure to clean all the old carbon and crap off the valve stems

[wardmoto]

Take note of the shinny appearance of the actual valve seat that is pressed in the head.  Coat the valve seat in the compound, install the valve (they make a tool for this, but I never used it)  I then press the tulip/head portion of the valve, forcing the grinding compound between the valve and its seat in the head.  I then twist the valve back and forth.  It will be rough for a while and seem to smooth out.  Pull the valve off its seat, spin it a bit and repeat above....it will be rough for a while and smooth out again. I do this a couple of times.  Pull the valve out of the head and wipe the compound of the valve seat and the valve...see the grayish dull finish on the previously shinny part??? That means you did it correctly...repeat 7 times.  Do not under any circumstances think that one grain of that compound won't cause your engine to ingest itself.   Clean off the compound religiously...On my 350F, I washed it with water and pressure, then a petroleum based parts washer shortly thereafter, followed by the valves being reinstalled in their correct original locations with lots of oil.  Put everything back together, start, ride and be happy.

[trinorman]

And after lapping be sure to test for leaks.  Here's how.  After lapping, install valves and springs.  It is recommended to use solvent (I use gas, but be careful with it if you do) and pour some into each intake and exhaust port, doing one at a time.  If you see any sign of moisture from the solvent/gas in the combustion chamber, it has leaked past the valve seat and you need to lap again until there is no leakage.  Test again.  If all dry you should be good to go.

[oldfart]

Hello,

I am currently rebuilding a CB550 engine for my cafe project bike.  The bike orignally had 8500 miles on it.  1977.  I have purchased a complete gasket kit that includes the valve guide o-rings.  Should I try to damage my guides by banging them out to replace the seals?  I have read that these seals can leak on the exhuast side.

What is the best method on removing the guides?   I assume they are hardened, so banging on them probably would not be wise.  I have seen then special tool in the manual but what else could be used?  Arbor press?

Thanks in advance,
Getting ready to get out of the driveway,
Greg.

The o-rings are only used when installing new guides.  You never reuse a valve guide once it is removed.  No, the o-rings do not have to be replaced, again, unless you have new valve guides to install also.