Original bits no longer needed - head R&R

So I'm finally actually working on my bike again - I do procrastinate!

With the head off, around many of the studs, not all there is a split plastic sleeve or bushing. It is brittle and some were already nearly dust when I took the head off.

There are no replacements in the engine rebuild gasket set.

Maybe they kept the stud from vibrating? Or inhibited rust and corrosion build up in that void?

I am assuming I don't need to worry about not having replacements since they aren't included in the kit.

Should I do anything in that gap wen I start reassembly?

Steve

 

There are no plastic parts. You may have orings that have well hardened.
On the two outer studs outside cylinder #4 are two rubber sleeves which are actually wide orings outside a metal dowel. They seal the oil galleys under pressure from the oil pump. If those are not there the engine will leak oil profusly. If they are bad then I will help yu look for new ones. McMaster-Carr should have some. We will have to mesure the length, diameter and thickness of the old ones so we can match them. Let me know what you find and we'll get on that.
The other metal dowels are to keep the head in position. You could miss some of those and be ok but the end ones and at least one more at the other side of the engine are critical. Some dowels stick in the cylider block and others in the head. So look under the head for any in it. NOTE:* with the camshafts out turning the head upside down will allow the shim buckets to fall out. Therefore if they get mixed up and are not returned to their original location the valve clearances will be off. So remove them and place them in correct order to avoid this. I use a plastic sectioned tray to keep them in order. Exhaust on top and intake on bottom in their correct order.
It is also a good idea to pull the buckets, remove the shims one at a time and write down the shim size in relation to it's valve position then put the shim back in and on to the next one. This way you will know when a clearance is off, what shim you will need to adjust without having to pull the shim. Very convienent to check the valves and then be able to go riding while shopping for the correct shims.
I am assuming that the 550 head is similar to the 700 but let me know exactly which bike we are talking about.

 

Yea, its the 550 motor.
Nope, not the o-rings, and the new ones came in the gasket set. Not metal dowels - solid or tubular, all accounted for.

All the bits nearly turned to dust was I tried to slip them off. Brittle as dried leaves. They were like plastic or Bakelite with a split so they were originally snapped/slipped over the studs. The studs don't have much rust or corrosion. They were on the non-passage studs only.

I've never seen these on any motor with head studs or bolts.
Oh well, I'm not going to worry about them.

I did manage to mix up the valve buckets since I had taken the cams off before I removed the head and promptly set the head down inverted to let the oil drain in a tub. oops. I'll remember next time.

Steve

 

Well I don't know what they are either. The 550 head is the same design as the other XJ's. I can't even find that part in the parts lists or diagrams. So I wouldn't worry about them. The metal dowels are the only critical part. Can't imagine why anything would be in there with them. There is no need for anything else except the orings on the end galleys. Check the orings that came with your set. If they have a small lip around one end then don't use them. I tried these on my head and it leaked like mad. I wound up pulling the head and putting the old ones back in. Easy test is that the wrong ones will only go in one way, so if you can't invert it and it fit in then use the old ones. Realy caused me greif until I figured it out. I put in two headgaskets after having the head shaved before I finally started suspecting the new parts.

 

I've found reminents of these "plastic" sleeves on two of the motors I've torn down off of Maxim 650s. Cleaned up and slapped (perhaps the wrong word, assembled) the engines back together. No problems.

 

Well that makes me feel better! Really wish I knew what they were.

 

If I remember correctly, the studs were covered with the plastic sleeve to help dampen noise or something?

They were also falling apart on my engine, I just ignored it and continued with the engine assembly.

 

As for the buckets dropping out and you not being sure on where they go, don't worry about it. Just install one cam and rotate around with the head off of the bike. Its much easier to check and replace the shims when you do not have to worry about timing the cam. Install cam and measure clearance, take notes, then change what was needed. Then repeat with the other cam. Do make sure you have the exhaust cam in the exhaust side and not the other way around tho. Just make sure you are taking care and do not bend any of the valves. Before you install the cams, spray some contact cleaner in each of the intake's and exhaust while they are closed. If one of them leaks then you might have to lap the valve in a bit more. If contact cleaner will leak you can bet that air will leak.

 

I am lapping the valves anyway, along with new stem seals.
For sure, setting the clearance before assembling the head back on the motor is my plan.

The older 550 (at least) makes it pretty easy to tell the intake from the exhaust since it has the mechanical tach drive on the exhaust cam.

The new cylindrical o-rings have no lip. The originals came out with lips. I'm pretty sure I already swept up and tossed the originals so I can't go back and compare.

Between dampening vibration or nose, and inhibiting corrosion were my original guess. Do brand new studs come naked or with the sleeve? I don't need new studs now.

I do need to get a couple replacement acorn head nuts before I do the assembly. One was a tad stubborn during removal and is a bit rounded.

 

Both my engines had the stud sleeves, both almost disintergrated. Did not replace them either.

My cams had the drive gear for a tach, but neither had the fitting on the head. Both cams marked Ex and In as well.

 

Those sleeves are there to slow corrosion of those studs... notice that they are Exposed to road spray?. Often the plastic crumbles and the studs corrode.. growing larger in he process.. Preventing the Cyl block from being removed.. V common problem and absolutely a Bugger to fix as the studs sometimes have to be cut.. in place.
Neither easy nor Fun to do.
Cannot believe this is news as most all Aircoled Yamas have these sleeves/problem.
Substitute ?? Heat shrink Tubing works V well.

 

I'd bet this issue isn't limited to Yamah, aircooled or not.

Allthough I do not see where any of these studs are exposed to the elements (on my XJ550 motor), I certainly belive in galvanic reaction. steel and aluminum alloys...
The heat shrink tubing is cheap and easy enough to be worth a try - even though I would hope to never have to pop the head off again!

Steve

 

You mean the studs that are surounded by the head gasket which fits so tight against the head and cylinders that it won't let oil past?

 

Thanks, that covers my question in XJ chat. Should have tried search first. I keep feeling like this coiuldn't have happened to anyone else but me ...could it?