ronstern,
Here is a description of the technique by member
grepper. He improved on my method considerably.
The big question, Is it possible to change your Valve Seals without taking the engine out and disassembling the head? Yes! But it's not easy. One of my bikes was leaking oil through the valves, so I took it upon myself to try it. Here's how I did it.
If anyone wants to chime in, even to say DON'T DO THAT, you are welcome.
Making the tool:
I couldn't find a Electrical Conduit Reducer as PAMCOPETE suggests, so I made my own tool. I bought a 1/2 inch pipe coupling from the local hardware store.
Next I went at it with my $15 Harbor Freight angle grinder (it's fun grinding metal, sparks everywhere), and cut a nice big window in it, leaving only about 1/3 inch wide support on one side and top and bottom rings only a few millimeters thick. I finished off with a hand file to make sure I got all the loose barbs off (don't want any bits falling into the engine).
Other tools I used were assorted clean screw drivers, a couple of pairs of needle nose pliers, and various wrenches, very good lighting and a LOT OF PATIENCE.
Now that I have my tool, I'm ready to take apart the valves. With the engine at TDC, I do one valve at a time, first removing the tappet cover, then the tappet out of the rocker arm. Also, I put a nice clean screw driver through the spark plug hole to catch the valve before it drops all the way down into the piston.
Next I slip one end of my tool between the rocker arm and the top of the valve spring, and the other over the rocker arm. I have a 8mmX1.0 bolt, nut and washer, feed it through the top of the tool and into the top of the rocker arm.
Here I have to make sure everything is nice and square, with the bottom of my tool centered on the valve. Then I tighten the nut down, compressing the spring down, but not the top of the valve and collets. With the spring compressed, I can gently push the valve up with my screw driver through the spark plug hole. The collets will come loose. Then very carefully I use a pair of bent tip needle nose pliers to take the collets out. My tool provides a nice catch for these, but it's still possible to drop them down into the head.
(If the collets do fall down into the head, go out to the driveway, stomp your feet and curse a bit. Then go out the back yard, grab a seat, have a cigarette, and watch the birds in the trees and calm down. Then go back into the garage and fish those collets out.)
Next, decompress the spring and remove the tool. Then I use a screw driver, forcing it between the spring and the retaining washer on top the spring and remove it.
Then I put my tool back in compressing the spring, this time there's no retaining washer on top of the spring (so I have room to pull the old valve seal out).
Note, exhaust valves can drop down past the seal, but intake valve do not. If the exhaust valve drops down too far and you lose the hold you have on it with the screw driver through the spark plug hole, it’s not all over. (Go through anger and calming exercise above). You can take the exhaust header pipe off, reach in there with some needle nose pliers and push it back up.
Next, I use my bent tip needle nose pliers to reach down into the spring and pull the old seal out. I found that I ended up grabbing the top first and ripping that out, then reaching in again for the rest of the seal. Again, be very careful not to drop any unwanted bits into the head.
After you have the old seal out, you can put the new seal in. I put my seal casually into the spring. Pushed the valve up and gently used my fingers to push the top of the valve past the top of the seal. With the valve up, I gently but firmly use the tips of my bent nose pliers and push the seal into place. I want to make sure I don't damage the new seal. I test the seal, moving the valve up and down making sure it stays in place.
(Hurray! I over half way done with the first seal)
I decompress the spring, take my tool out.
I pop the retaining washer back on to the top of the spring. Then put my tool back in, compress the spring, push the valve up, put the collets back in, and decompress the spring. Then take my tool out. Put the tappet back in. Set my valve clearance, put the tappet cover back on and I'm done with one valve.
Honestly it took me about 45 minutes to do one seal. I didn’t rush things, and even though I was very careful, I found that getting the tool square on the spring was not easy. If I didn’t have it square, I had to decompress, square it up again, and try again. With things not square and centered, I would not be able to get the seal in or out, the collets didn’t want to go back in, etc… After I finished, I wonder if it would have been easier to just take the engine out, maybe not, that’s not easy either.
Again, credit to member
grepper for this ingenious technique...
So, in your case you could use this technique to remove the collets, then remove the rockers, then the valve springs. Be sure that the pistons are at TDC so the valves do not drop down into the cylinder. When I did it, I found that I could hold the valve in position with a screwdriver through the spark plug hole, but you have the exhaust and carbs off, so you can reach in intake and exhaust ports to hold the valves in place if necessary. Be sure to block all the oil return passages with a rag so the collets cannot drop down into the sump.
Can someone explain to me the correct orientation and fitment of the valve springs please, I hadn't realised that there was a difference in tension at each end or is this a windup?
