Author Topic: Valves (Read 2816 times)

Doug Moon · « **on:** June 12, 2008, 11:57:46 AM »

Does anyone have the correct procedure for removing the valves from a Saito 56 cylinder head.

I have a 56 that has been sitting for about 3 years. I did put in after run oil after the last use.

I pulled it out to use on my new plane and the exhaust valve wont close all the way and is leaking during compression stroke. It also sticks closed once it is closed as far as it will go. Needless to say this is not good. When I first took it out and set it up on the test stand to run it in some it ran fine and had some compression but felt weak. Now it will free wheel like there are no valves in it.

I have the cylinder and the ring is in good condition it just appears there is old gunk on the valve seats and guides. Disassembly and cleaning should cure the issue.

I just cant figure out how to get the retainer clip off the valve. I am sure there is a tool needed as well.

Any input is greatly appreciated and pics would be great too.

I don’t want to send it in because I want to learn how to do it myself. This stuff is fun to me. If I screw it up I will sell off some motors and get another one, which I will probably do anyway.

Thanks in advance.

Bill Gruby · « **Reply #1 on:** June 12, 2008, 12:21:48 PM »

Doug;

Get hold of Bob Reeves, he is a regular on this Forum. He should be able to help you out.

"Billy G"

keith sandberg · « **Reply #2 on:** June 12, 2008, 01:45:52 PM »

Doug, you won't need any tools that I'm sure you don't already have. Pull the cylinder off at the base, four cap scerws, set the cylinder assy. on a dowel clamped in a vise (to hold the valves closed) and remove the rocker arm. Now push down on the valve spring and remove the clip with a small screwdriver or pick. I try not to mix any parts between the intake and exhaust sides so they go back together just as they came apart, also I try not to rotate the ring on the piston. After the cylinder assy. is put back together hold it upside down and fill it with fuel to see if one of the valves is leaking. Easy job and I'm sure you'll do fine, Keith

Doug Moon · « **Reply #3 on:** June 12, 2008, 02:38:24 PM »

Thanks for the how to on valve removal. Sounds easy enough.

Now, about that ring. This motor has tons of time on it and I have ordered new valve springs and a ring as well. Is there a position the new rings needs to placed on the piston? I know how to get it on the piston I just want to make sure it goes back in the right place.

Thanks

don Burke · « **Reply #4 on:** June 12, 2008, 03:24:00 PM »

I had the same thing happen with an OS48 I hadn't run for a couple of years. Liberal application of WD40 then sitting overnight and gentle hand cranking cleaned out the congealed oil that was making the valves stick. I also pulled of the valve cover and doused that area really well with the WD40.

Bob Reeves · « **Reply #5 on:** June 12, 2008, 03:27:46 PM »

Doug was one of the guys that helped me when I first started messing with Saitos. Sounds like Keith is the man.. Although I have ran many Saitos, haven't had to work on the inards yet.

Jim Kraft · « **Reply #6 on:** June 12, 2008, 07:41:21 PM »

When you pull the cyl. off just mark the ring gap position with a magic marker. Try to get it back on in the same position. I don't think it is critical, but it can't hurt to get it the same if you can. You can reseat the valves with Dupont #7 white compound. I put a little compound on the valve, put it in the head, take a piece of fuel tubing and put over the valve stem, chuck the other end in an electric drill, and with a slight tug on the drill spin the valve. It will clean up the seat and the valve for a nice seal. Be sure to clean all the compound out before reassembly. Pipe cleaners work well on OS valve guides.

Doug Moon · « **Reply #7 on:** June 12, 2008, 10:00:13 PM »

Here is the latest.

Got the valves out and cleaned them with a wire brush on the dremel. There was a ton of gunk on the exhaust valve stem. Got it all cleaned off the valves and just very lightly cleaned the seat in the cylinder. Nothing really in the guide and it was easily cleaned away.

Looked great. Assembled the motor. I never had the cam out so it was very easy and quick.

No rocker arms on yet but I have the cylinder in place. Went to check compression and you can hear it leaking through the exhaust valve as you roll it over. It is so bad you can roll it through compression without a prop on it.

I came on hear and read about seating the valves. Thought that has to be it.

Install valve with 3m white compound and chuck it in the drill and go for about 10-15 seconds per valve lightly tugging on it and then letting up and tugging again. To make sure I did this correct let me tell you what I did. I put compound on the valve angle that touches the seat. Then slipped in through the guide. Carefully chucked the end of the stem in my drill. It barely reached but it was enough. Then let the drill stand there on its own balance and held the cylinder as I squeezed the drill's trigger. Very lightly pulling the cylinder away from the drill to really pull the valve into the seat. Sound correct? Assemble motor and same thing leaking air like a siv.

Bent valve? It doesnt appear to be bent. I guess one way to find out is to switch valves and see if it leaks on the intake side?

Gordon Tarbell · « **Reply #8 on:** June 13, 2008, 09:19:41 AM »

Don't switch valves , just look for the lapping mark that the n0.7 left on the seat face of the valve. It should look like a dull grey ring all the way around . If it is not all the way around then the valve could be bent. Also check the dull pattern on the seat in the head to be sure the lapping mark is all the way around and uniform in width. with the valve assembled in head(springs retainers and keepers but no rockerarms) but off of the engine turn it up side down and check for leaks with light oil (wd40) , if no leak then try some solvent , solvent will leak through where oil won't.

Doug Moon · « **Reply #9 on:** June 13, 2008, 09:58:44 AM »

I had cylinder updside down with valves installed I would blow into it and could hear a tiny leak but I sure had to blow hard, whew!

So i put some water in it and blew into it again and then tilted over a few drops came out and the exhaust port. The leak is on the exhaust port/valve.

If I hold the valve and spin it there is no visible out of round or bending, I am sure it doesnt take much.

Should I keep lapping it with compound? The stuff I have is NOT very abbrasive, you can feel it but it very fine grit. Should I procceed to try for a fit or just buy new valves?

Problem with buying new valves is they are on backorder at Horizon...

Doug Moon · « **Reply #10 on:** June 13, 2008, 12:14:32 PM »

Gordon,

I was panning on switching valves check for leaks only, NOT run it with them switched. My thinking was if the valve is bent or damaged the leak will follow the valve. If the guide is bent or the seat is damaged then the leak will continue in the same place.

Will this work?

Randy Powell · « **Reply #11 on:** June 13, 2008, 01:37:21 PM »

Doug,

You are dealing with wear issues, I imagine. It may be that the seat or the valve was worn unevenly. If light lapping didn't do it, I would seriously think about replacing the exhaust valve and lapping it in. Are you sure that the leak is comming from the seat and not the guide or (God forbid) a crack in the head?

If you are sure the leak is comming from the seat/valve, then as I say, I'd replace the valve just to be sure that it wasn't bent. But if you're certain that the valve is straight, the you can probably just continue to work on lapping the seat. I usually do this by hand with a valve seat tool (looks like a stick with a suction cup at each end) starting with fairly course grit and moving to finer grit once I have a good, even seat all the way around. I made a valve tool for my Saito using a dowel and the rubber suction cup end from a dart gun dart. Worked for me. I'm too paranoid about damaging the valve guide to use a drill, but that is probably what it is: paranoia.

Jim Kraft · « **Reply #12 on:** June 13, 2008, 01:50:27 PM »

If the valves are the same size I would sure try that Doug. It might be that the seat/guide is leaking around the outside and not at the valve seat. Also make sure the valve springs are good. They can get weak also. You may be able to shim the spring just to try that.

Randy Powell · « **Reply #13 on:** June 13, 2008, 02:18:37 PM »

Jim,

Only thing to be concerned about on switching the valves is that the intake valve is already seated. If you move it to the exhaust position, you may have to re-lap it into the intake seat. Still, not a bad test.

Jim Kraft · « **Reply #14 on:** June 13, 2008, 02:22:55 PM »

Good point Randy. These little guys can be a little hard to get a seal anyway.

Doug Moon · « **Reply #15 on:** June 13, 2008, 02:29:59 PM »

I have ahd it apart 3 times now and each time I put it back togther the intake valve seals up and there no leak there, at least I cant hear it there and it didnt leak with fluid in it.

Leaky guide can cause the valve to not to seat correctly? I guess the angle can be off??

New springs, retainers, keepers, ring, and intake manifold are on the way. Went out today from Horizon. Horizon put new bearings in this motor several years ago and then it was put on the shelf. I am sure I will end up putting in new valves or the cylinder. It will be basically new at that point. Cool!

I will get this figured out and I have sure learned alot over just the past few days with it. Not to mention it has been really fun.

Randy Powell · « **Reply #16 on:** June 13, 2008, 02:46:46 PM »

Doug,

It seems you have the same sort of warped sense of fun I do.

Alan Hahn · « **Reply #17 on:** June 13, 2008, 03:07:08 PM »

My question is whether there was a problem with the engine before you put it away 3 years ago?

If not I then wonder if you really have a problem or not. A small leak that you can detect by flipping may be completely gone when the engine is running. I would take a look at the valve, and the bottom of the exhaust seat to see if you can really see any thing wrong--like a scratch.

Here is a quote from the booklet "A complete guide to Saito Model 4 strokes" by Graham Rice

"I would not recommend the practice of lapping Valves to improve Valve seal. The removal of all traces of lapping compound from impregnating the bronze Valve seats permanently, is quite difficult." [

]
"Providing the Valve seats are not scratched, Valves will bed down into their bronze seats with running. I have found, simply rotating the Valve head to a new position sometimes works."

Finally about the ring, it will eventually rotate where it wants to be, so I don't think that it matters too much where the gap is located. According to the same booklet, the recommended gap for the 50-80 sized Saito is 0.008". You need this to get lube down to the bottom--but you knew that already.

Doug Moon · « **Reply #18 on:** June 13, 2008, 03:34:01 PM »

Alan,

This one is a bit newer and does not have the bronze seats. It uses the aluminum.

Good point about the compound for lapping the valve. They told me on the horizon tech line I shouldnt have to lap the new valves and they should seal up tight with no leaks.

The motor will run in its current state but the power is down some.

When this motor was put up it wasnt mine. It was my brothers and he brought it over to let me use it in the new plane. The history on it is that it was running all well and good and then at the nats in 2001or 2002 it burned up the bearings and quit running. Steve sent it to Pete at Horizon and he setup new bearings for it and sent it back. Steve had a new 56 by then and this one went on the shelf.

Randy,

My wife thinks I have a weird sense of fun as well. I told her I couldnt wait to break down the Saito and work on the valve train and she looked at me with a little head tilt and said "oooohhh kaaayyyyyy?" Like I was from Mars.

Randy Powell · « **Reply #19 on:** June 13, 2008, 03:43:59 PM »

Doug,

Try takingapart an RCV if you want some REAL fun.

Doug Moon · « **Reply #20 on:** June 13, 2008, 08:35:09 PM »

I switched valves, keeping the springs in the same position as original. Still leaking. Then I switched the springs and still leaking.

I guess my only recourse now is get a new cylinder and or try to lap this one into a seal.

Douglas Babb · « **Reply #21 on:** June 13, 2008, 08:53:50 PM »

Remember to go light, as you lap it into the seat the valve will move deeper in and you will have to grind on the stem to preserve the clearance between the rocker arm and stem. If you have access to a micro lathe chuck the valve in it and use a dial indicator on the valve head to check if it is bent (probably less than a thousandth).

Jim Kraft · « **Reply #22 on:** June 13, 2008, 09:00:07 PM »

Saitos have adjustment screws on the push rod end of the rockers so that you don't need to grind on the valve stem to get the right clearance.

Gordon Tarbell · « **Reply #23 on:** June 13, 2008, 10:31:25 PM »

If you switched valves and the ex. side still leaks, its not the valve (scratch or nick, crack at the seat face or around the outer edge where the seat is pressed in the head. I havn't had my saitos apart that far but have 35 yrs of history with larger high output Ic engines. The game is the same only on a different scale. Suck ,squeeze, bang, and blow. I would look real hard for scratches on seat face and spring pressure. If the clearances are set correct and all else looks good, then fuel it up and spin it with the elec finger and let her run for a while and see if it seals up that ex leak at valve.

Douglas Babb · « **Reply #24 on:** June 17, 2008, 12:30:39 AM »

Sorry Jim, my mistake. I have six of the things and have not had the valve covers off or made adjustments to them yet, guess I need to run the heck out of one so I can use the tools that come with them.

Doug Moon · « **Reply #25 on:** June 17, 2008, 07:42:58 AM »

I got new 62 for fathers day. It doesnt have a hole ton of compression compared to a 72 but there is a pop at the top as it goes over. Something the 56 does not have.

Jim Kraft · « **Reply #26 on:** June 17, 2008, 08:47:36 PM »

Doug; You did not say if the exhaust valve leaked when you put it in the intake side. If it did not it has to be leaking through the exhaust seat/guide.

Doug Moon · « **Reply #27 on:** June 18, 2008, 12:07:29 AM »

Jim,

I switched them and it still leaked on the exhaust side. So I guess it is the seat. Pretty much have to replace the cylinder at this point. They dont have seat inserts anymore. It is just part of the cylinder. I can try to lap it in but it is hardened aluminum.

Lauri Malila · « **Reply #28 on:** June 18, 2008, 09:53:33 AM »

The thing is, that you should do the lapping with a lapping tool that is softer than the metal to be removed. Lapping compound gets embedded into the softer part and cuts the harder. Now the steel valve is propably wearing faster than aluminium seat.

L

Author Topic: Valves (Read 2816 times)

Alan Hahn