Removing valve spring without removing the head?

76 Kz900. Thought I might try to remove #4 EX & IN valve springs WITHOUT removing the head? Thought I'd try two methods...

1) hook up compressor to #1 & #4 and pressurize both pots at 100lbs PSI, to hold the valves closed. Would it hold at TDC or would the pressure push them down to BDC? Are both Valves closed at BDC?

OR

2) take #4 to BDC, remove plug and feed in say 50' of string/cord, through the plug hole then rotate #4 up to "compress" the string/cord against the valve?

Anyone ever done either? Thoughts? Thanks.

In my experience, the pressure pushes the piston down until a valve opens and all the air escapes. You have to stop the crank from turning.

well if you think of it you will have the cams out so there will be no way that the valves open.removing the spring keepers will be no problem.But when you go to reinstall the springs how would you compress the spring enough and hold it down till the keepers are reinstalled??? and yes the compressed are in the cylinder will hold the valves shut

Once you have the camshafts out there is not a whole lot to pulling the head. Especially if it's been off recently
I've been getting a good bit of practice.

How are you going to compress the springs once you get the valves corralled?

Why do you want to remove the #4 springs?

If a tree falls in the woods...

Rammy, real good point there about no cams so what's going to open the valves. You're thinking outside the box again. Why didn't I think of that!

Duck, I know, I know. Just pull the damn head off AGAIN. Then maybe, THIS TIME, I'll be tempted to actually pull the block and go look for the broken oil ring on #4 I KNOW I've got.

Why didn't I do that 3 weeks ago, when the head was off? Huh, Huh.

Looking for a blameee. Anyone?

You are having one HELL of a time with that engine arent you!!!!Beleive me I just went threw what you are going threw now with my650. SMOKE AND MORE SMOKE.I had done e-thing but the valve guide seals.Was out 1 night a week or two ago missed a gear running a crotch rocket and OOOPPPSSS floated and bent a valve so off come the head again.Replaced the guide seals and the only smoke there is is right afer start up for about a minute or so then goes away. Good luck and save the gaskets asfor they will start to get spendy$$$

Sorry to hear about your troubles.

I've got 1,2&3 running right on the damn money, absolutely NO smoke, tan plugs....then there's #4!!!!!!

Doesn't smoke immediately on startup. Starts smoking after about 1 min then pretty heavy until 20 miles when it calms down to about 50% of what it was during the 1st 20 miles.

I know i'ts the oil ring on #4. I'll be gobsmacked when I get back in there and find it isn't? I just cant bring myself to take another day and a half to rip the thing back down and put it back together.

Doesn't have a little door hidden away somewhere, just behind pot #4, that you can change the rings through, does it?

I just cant bring myself to take another day and a half to rip the thing back down and put it back together.

You should be at book rate by now!

You can pull a plug and use a small rope on top of the piston to hold the valve up. Just feed the rope in when the cylinder is not at TDC and then rotate the piston up.
I don't see how a oil ring would make a cylinder smoke. Have you tried "Ring free" from Yamaha? It's great for freeing up stuck rings and removing carbon.

An oil ring can make it smoke, as can compression rings or a worn-out cylinder, but if the rings are bad enough to cause much smoke, the cylinder will likely be FUBAR and need rebored. This will show with a dry & wet compression-test. Valve guides and seals are the most common causes for large amounts of smoke, especially before the motor warms-up, fading as it gets warmer.

If I had a tool to do it with easily, like I do for a Chevy or Ford (with valvesprings that aren't stuck down inside a hole), and wanted to replace a spring or seal, I'd air-up the cylinder with a compression-test adapter with the check-valve removed and go to work. However, the only tool I have for recessed valve springs is a big clamp device that has to reach the underside of the valve to work.

Hate to hear about that. I feel your pain. Lots of work goes into rebuilding these motors, if first you dont succeed try try again,look at the bright side you did get her running.