Valve lapping questions ? compressor suggestion, lapping compound, is it even needed?

[Andrew Vanis]

Valve lapping questions – compressor suggestion, lapping compound, is it even needed?

About 14K miles on my engine. Have the head off to replace leaking gasket. Gasket is $70 so don’t really want to take the head off again. Wondering if I should lap the valves and how would I know/check if they need it?

If the answer is yes, then:

Where do I get lapping compound and what kind do I get?

Which of these spring compressors would be good?

Universal and I like the lever idea - http://www.ebay.com/itm/Valve-Sprin...ash=item2c927614d1:g:avMAAOSwZjJU7yJE&vxp=mtr

Nice box - http://www.ebay.com/itm/5-Sizes-Val...:g:0R0AAOSwYmZXLp2i&item=252382245929&vxp=mtr

“Professional” - http://www.ebay.com/itm/Wilde-Tool-...:g:SMcAAOSwq7JTyypz&item=201197469915&vxp=mtr

Too bad the Autozone loan-a-tool compressor doesn’t seem to work (or does it?) - http://www.autozone.com/loan-a-tools/valve-spring-compressor

I saw the 4-age lapping PDF off basscliffs site and Steve’s DIY PVC spring compressor video is no longer active.

 

[tkent02]

Check with gasoline in the combustion chambers, if it's not leaking and if your compression is good then there's no need to take lap anything. Unless it's smoking there's no reason to take anything else apart. One school of thought. The other school is while you're in there, replacing the valve stem seals might be a good idea, just because they are 35 years old and likely hard as a rock.

I would do it just because it seems like a good idea. This is the only one of your three that will work on these heads:

http://www.ebay.com/itm/5-Sizes-Val...:g:0R0AAOSwYmZXLp2i&item=252382245929&vxp=mtr

Because the valves are down inside the bucket bore.


Replacing the cylinder base gasket is also a good idea, if it gets disturbed at all when the head is off it will leak.

 

[Andrew Vanis]

Check with gasoline in the combustion chambers, if it's not leaking

How?

and if your compression is good then there's no need to take lap anything.

Can’t do that with the head already off I don’t; think, Or can I?

Unless it's smoking there's no reason to take anything else apart.

Don’t; know since it hasn’t ran for a while – are you talking shome in the exhaust or off the crankcase from the external oil leaks?

One school of thought. The other school is while you're in there, replacing the valve stem seals might be a good idea, just because they are 35 years old and likely hard as a rock.

I would do it just because it seems like a good idea.

Yeah, what’s another $80 OEM ($30 aftermarket) but if I don’t need to touch the valves, I’m inclined to leave in what is in there.

This is the only one of your three that will work on these heads:

http://www.ebay.com/itm/5-Sizes-Val...:g:0R0AAOSwYmZXLp2i&item=252382245929&vxp=mtr

Because the valves are down inside the bucket bore.

Ahh so I need one with extensions on the C for both sides. Good to know.

Replacing the cylinder base gasket is also a good idea, if it gets disturbed at all when the head is off it will leak.

That would require reseating the cylinders no? Pricewise not much $11 gasket and 4x$5 orings. Really inclined to leave this one alone considering the cylinder work and the issues of maybe not seating the rings right.

 

[Andrew Vanis]

Also, what kind of lapping compound?

this one has a nicer case (latches specifically) and at $18.50 only $1.50 more than least expensive Ebay and free Prime shipping http://www.amazon.com/8milelake-Cla... motorcycle&qid=1464742978&ref_=sr_1_5&sr=8-5

still not ordering it unless if lapping is even needed or at least a REALLY good idea in my case. More detail requested of all ya'll readers.

 

[Nessism]

Most definitely remove the valves and lap, and replace the valve stem seals.

For the spring compressor I'd get the one labeled "nice box". It's cheap and good enough.

Any general purpose lapping compound is fine. Lapping is mostly just to clean the valve surface anyway. If you are spending more than 1 min. per valve it's too much.

 

[blowerbike]

if it's the bike in the op's sig....it's a rocker arm valve train...
just sayin...

 

[Andrew Vanis]

if it's the bike in the op's sig....it's a rocker arm valve train...
just sayin...

it is on that bike. this is teh valves I have - http://www.partzilla.com/parts/search/Suzuki/Motorcycle/1981/GS750L/CAM+SHAFT+-+VALVE/parts.html

What are you trying to convey in your message?

 

[blowerbike]

post #2 assumes your bike has shim and shim buckets...aka an 8 valve model rather than a 16 valve.

 

[Andrew Vanis]

post #2 assumes your bike has shim and shim buckets...aka an 8 valve model rather than a 16 valve.

for someone not knowledgeable in the differences, what should i be concluding from that? aka-what difference does it me for my style of valves?

 

[blowerbike]

8 valve models have larger valves.
16 valve models have smaller valves.
right off the top of my head that means you need different size valve lapping sticks/cups.

 

[tkent02]

Not sure but do the other style valve compressors work on the 16 valve heads?

 

[blowerbike]

i have only had one style of compressor for all my years..
it's the one with the lever you move and then you take up all the slack in the bolt that you turn to compress the spring.
this type cuts down on all the turning to and from and i have used it on 8 and 16 valve models.
mine says "made in japan" on it.

 

[posplayr]

for someone not knowledgeable in the differences, what should i be concluding from that? aka-what difference does it me for my style of valves?

Determine which you have and act appropriately. Does your "L" have 8 valve? 2 per cylinder or 4 per cylinder?

 

[Andrew Vanis]

Determine which you have and act appropriately. Does your "L" have 8 valve? 2 per cylinder or 4 per cylinder?

4 per cylinder (16 total). this style - http://gsarchive.bwringer.com/bikecliff/images/16valve_adjustment.pdf

what is the appropriate action in that case?

 

[Andrew Vanis]

8 valve models have larger valves.
16 valve models have smaller valves.
right off the top of my head that means you need different size valve lapping sticks/cups.

I was going to not us the cups/sticks and either use the tube over the stem and pull/turn or the hose on the end of the drill a'la the manual on Basscliff's site http://gsarchive.bwringer.com/storagecliff1/images/HOW_TO_LAP_VALVES.pdf

 

[Andrew Vanis]

Originally Posted by tkent02
Check with gasoline in the combustion chambers, if it's not leaking



How?.



Found this which was insightful. will try that.......

â?‚?¢ Clean and assemble the head and valve components. Fill the intake and exhaust posts with gasoline to check for leaks. If any leaks occur, inspect the valve seat and face for burrs or other things that could prevent the valve from sealing.

 

[Steve]

Yeah, what’s another $80 OEM ($30 aftermarket) but if I don’t need to touch the valves, I’m inclined to leave in what is in there. ... That would require reseating the cylinders no? Pricewise not much $11 gasket and 4x$5 orings. Really inclined to leave this one alone considering the cylinder work and the issues of maybe not seating the rings right.

The process of removing the head has already disturbed the seal on the base gasket, most likely rendering it useless, but you won't know until you get the engine all back together and find that it leaks. Like you say, it's only $11 (now), but it's another $200 gasket kit if you need to do it over.

Originally Posted by tkent02
Check with gasoline in the combustion chambers, if it's not leaking



How?.

Turn the head upside down with all the valves installed and closed. Pour some gasoline into the cumbustion chamber, let it sit for a while. If the valves leak, the gas level in the chamber will go down.

.

 

[blowerbike]

I was going to not us the cups/sticks and either use the tube over the stem and pull/turn or the hose on the end of the drill a'la the manual on Basscliff's site http://gsarchive.bwringer.com/storagecliff1/images/HOW_TO_LAP_VALVES.pdf

sounds like a plan to me...

 

[Steve]

I was going to offer my suggestion how to do it until I clicked on the link. :-k

Those are MY grubby hands in those pictures.

.

 

[Andrew Vanis]

The process of removing the head has already disturbed the seal on the base gasket, most likely rendering it useless, but you won't know until you get the engine all back together and find that it leaks. Like you say, it's only $11 (now), but it's another $200 gasket kit if you need to do it over..

OK, let.s say to do the base gasket, what does that involve as far as dealing with he cylinders? Ring compressor? If I.m that far, should I replace the rings and hone he cylinders? If I just put the cylinder head back with the old rings what other issues am I causing?Also, my base gasket shows some o-rings, do those get replaced if the base gasket does? See schematic link aboveLet me know because at this time I.m thinking of doing the gas test on the valves and if that passes put the thing back together take my chances on the base gasket and stop this trip down the rabbit hole.