Please help me confirm what i suspect. HEAD GASKET

hello all,

my 82 750 maxim is having some issues. 38000 miles

noticed oil collecting on the fins of cylinder. wiped off came back. looked closer to me it sure looks to be coming from the part line between the head and cylinder. no oil above it, oil below it. I don think there is anything else in that area?

thought it was just the clutch side corner cyl 1. looking more it looks like the whole gasket is a bit wet with a mess along the whole front edge of the part line.

did a compression test, warm. results are 1-4 , 110 117 115 110

which is below 128 min(so I have read)

now that was with a harbor freight compression gauge so I doubt those numbers are dead on, but that's low enough to be out of the fudge room. I have had good luck with cars with it, when reading 180ish psi, it was very similar to another gauge. so there is some variance but I am so far inclined to believe it.

I don't feel or see any puffing coming form the part line, like a large air leak.

Valves are in spec FYI, it is running fine, but the oil leak is not fine.

so thinking I need head gasket?

so far thinking I will leave it in frame to fix. but maybe pull the cylinders and do rings just because?

 

photos not great but you can see the area I am talking about

 

well your comp numbers are all close to each other which is good,
did you test with throttle wide open? it is debated as when to test hot or cold?
do you have access to another tester?
do you need to comp for altitude ? then baremetric presure on the day of test?

check for oil around spark plugs there is a drain to the front of the head.

"thought it was just the clutch side corner cyl 1." my clutch is on the right side of bike cylinder 4

 

baby powder to track leak
you may want to retorque head to see if it solves problem

 

did it with throttle closed and open. cold, warm, hot. no other gauge handy no comp for altitude, I think Im pretty neutral in ND. no oil around plugs, bone dry. and bone dry in generally above the head cylinder part line.

when I said clutch I meant clutch lever side. so as sitting left hand side.

previously tried to retourqed head nuts.

didn't do baby powder test.

since posting this I have, removed tank, carbs, exhaust, valve cover. when exhaust was removed showed even more nastiness in there.

pretty committed to pulling head at this point.

going to map valve clearances just to have them, then pull cams and head.

 

make sure you get a oem gasket from chacal, a whole set isn't much more, sooner or later you'll need them. pay attention to the cam chain tunnel.

 

90% of the time the oil is coming from the valve cover gasket and running to the head part line, which makes it look like a head gasket problem. Pay particular attention to the inner part of the gasket near the cam chain.
Have you ever replaced the rubber doughnuts on the valve cover bolts?

 

I appreciate the replies.

deffinatly wasn't the valve cover, and it was previously replaced with doughnuts and no oil paths running from that area or the top of the head.


any way...

its all apart now. head and cylinders are off.

these bores don't look like they are coated with anything? is that correct? no risk honing or machining jugs?

the studs have a plastic sheath over them. most are broken off. what remain are in rough shape. thoughts on those? replace? break off whats left?

 

hers some pics, for what its worth the head gasket was wet with oil on both sides. to my knowledge I did spill there. but I suppose that's not damning.

either way I am in this situation now, no going back. took about 3 hrs so not much lost

 

Since you have the head off ,remove the valves and lap them in and put new seals in . NAPA if they have a machine shop should be able to do the valves (but you will have to provide the seals) . Once you have this buttoned back up , you will need to check and adjust valve shims ....This should have been checked before if valve clearance is way off this can effect compression readings . By the way your readings were not terrible , still chalk it up another gauge might give a different reading . Make sure you thoroughly clean around mating surface , ensure nothing gets into engine ( sure you already knew this ) but make sure you order the gasket from either xj4ever or your local Yamaha dealer this will ensure you get the best quality and correct gasket. Keep us informed on your progress .

 

The bores are iron,so they an be bored (specs are in all of the service manuals, and the information overload hour).
The plastic on the studs is there for noise reduction, and some other purpose which I forget. They don't hae to be replaced, but if you want to Chacal sells them (some people have used electrical shrink-wrap).

+1 on ordering the gasket from Chacal or the dealer (Chacal has them on hand, the dealer does not). There are several sets of head gaskets out there that have the cam chain tunnel gasket too thick. Using one of those sets will give you a different leak, or a cracked head.

Also be really attentive to the order of retorquing the head and barrels. The front mating surfaces of the cam chain tunnel can be a bit tricky to get right, and if you don't snug it all down slowly it will leak there.

 

Cool, thanks. I have FSM.

And not my first engine, but never did this engine before so that's new to me.

 

I also forgot to mention that Chacal carries a head gasket that has the cam tunnel gasket integrated into it. I think that the one Yamaha sells still has the cam tunnel gasket separate from the head gasket.

I figured this wasn't your first engine. This one is really well designed, and built. It just has a few quirks.
If you can get a copy of he Haynes manual as well that would get you all the information that's missing from the FSM. There are a bunch of errors in both manuals, but the FSM has all the correct information for this particular job.

 

Chacal has been in touch.

Trying to find a subtitle hone, not doing well. Would rather not take it to machine shop

 

If the bores measure good (not egg shaped, no low spots) then you should be able to get a ball hone in the correct size. Chacal might have them.

 

Yes I have to snap gauge them still. But assuming good I have a 3 legged stone hone, but wonder if ball would be more appropriate. But then it's a, matter of finding that size

 

Cylinder Hones:

These medium-grit, flexible CYLINDER HONES are just what’s needed to apply a proper “clean-up” cross-hatch finish to a set of cylinders before installation of original or new rings. Hundreds of balls of round coarse-grit oxide are attached to flexible twisted-wire shafts, which when chucked into a 3/8” or 1/2” chuck standard drill (or drill press) can be used to break the cylinder wall glaze and eliminate any high spots on the cylinder wall, creating a fresh surface finish that allows rings to seat properly, insuring the highest compression and lowest oil migration. These hones will not remove metal (and are not designed to do so, nor will they typically remove the top-of-cylinder carbon build-up “ridge”). Proper use requires the application of honing oil and precise control of hone rotation and linear (in-and-out) speed of motion. Just a few passes is all that’s needed , and it’s remarkably easy to use ---- its self-centering action allows you to produce a beautiful and professional cylinder wall finish even for a first-time user!

The use of these hones will greatly increase the success of your engine rebuild, and should be considered a “must-have” tool if your are not having your cylinders actually bored and/or refinished by a machine shop.

Each hone includes a sufficient supply of honing oil.


HCP22811SET Aftermarket engine CYLINDER HONE, proper size for use on all XJ550 engines. Includes a bottle of honing oil.
$

HCP22812SET Aftermarket engine CYLINDER HONE, proper size for use on all XJ650 engines. Includes a bottle of honing oil.
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HCP22813SET Aftermarket engine CYLINDER HONE, proper size for use on all XJ700 air-cooled and XJ750 air-cooled engines. Includes a bottle of honing oil.
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HCP22814SET Aftermarket engine CYLINDER HONE, proper size for use on all XJ700 water-cooled, XJ750 water-cooled, and all XJ900 engines. Includes a bottle of honing oil.
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HCP22815SET Aftermarket engine CYLINDER HONE, proper size for use on all XJ1100 and XS1100 engines. Includes a bottle of honing oil.
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Found hone

 

What is standard piston size? Manual states every piston is labeled on the crown. I have the arrow but nothing else. Inside the skirt it says 5g200 if that's anything. I can measure them but don't know base. And for alternate sizing it just shows plus whatever, but no totals

 

750 engines are 65.00mm standard bore. Oversizes come in 4 sizes: 65.25mm, 65.50mm, 65.75mm, and 66.00mm

 

That's all you'll find there....the arrow points forward, and it's imperative that the piston be aligned in that manner. The 5G200 cast inside the skirt indicates it is a 750 standard bore piston.

 

Oh good. My bores appear standard as well, (I haven't checked all in all locations yet) and a standard piston makes sense. So it looks like std rings should work out. Pending how the hone finishes out.

 

Honing won't change bore size, at all. It used to be known as "glazebusting" and that's all that it does: it will "rough-up" the mirror-smooth surface and put that nice cross-hatch pattern on the walls, which allows new rings to seat properly and quickly.

You need to measure the jugs properly for bore size, taper, out-of-round, as well as the straightness of the deck surface:

Bore: 65.00mm
Limit: 65.10mm
Taper max: 0.05mm ( 0.0020”)
Out-of-round max: 0.01mm (0.0004”)

Piston clearance: 0.030 - 0.050mm (0.0012 - 0.0020”)
Piston clearance max: 0.10mm (0.0039”)
Piston weight with pins, rings, clips:
Piston measuring point: 7.50mm from bottom of skirt perpendicular to pin hole axis

Ring gap:
Top: 0.15 - 0.35mm (0.0059 - 0.0138”) Limit: 1.00mm (0.0394”)
Mid: 0.15 - 0.35mm (0.0059 - 0.0138”) Limit: 1.00mm (0.0394”)
Oil: : 0.30 - 0.90mm (0.0118 - 0.0350”) Limit: 1.50mm (0.0591”)

Ring side clearance:
Top: 0.03 - 0.07mm (0.0012 - 0.0028”) Limit: 0.15mm (0.0059”)
Mid: 0.02 - 0.06mm (0.0080 - 0.0024”) Limit: 0.15mm (0.0059”)
Oil: n/a

Ring end gap orientation:
see diagram in svc. manual

Mating surface:
0.00 - 0.03mm (0.0000 - 0.0012") is okay
0.04 - 0.24mm = re-surface
over 0.25mm (0.100") if over this amount, jugs are junk and should be replaced

 

oh what a day. of cleaning a prepping.

happy to say honed out nice. everything specd correct and it is all still within standard tolerance.

now for parts

 

The hard part is over!

 

fixed I think. time will tell. all back together and carbs retuned to new environment. forget the numbers (as the gauge is cheap) but picked up 20(average) PSI in all cylinders. it is running on 4, and sees happy. probably better than before. it will take a me while to get comfortable and trust it again and it seems whenever you open a motor and get back together it seems to make new kinds of noises. I spose things did change or its all in my head, not bad sounds. more like its a different voice.

started instantly, idled a bit. cool down. repeat a few times. then works on tune. then now just road about 20miles. varying RPM and load on the bike. haven't taken it up high yet. figure let the rings seat in. and im still burning off all the oils and finger prints and all that.

I spose 100 miles? run it around varied. then an oil change and call it good?

also observation. manual has you removing and installing cams but unbolting the cam gears. are you guys doing that? it seems totally uncessary and I did not do it that way. it id the what I would call the "modern" way. as in all my more modern yamahas leave that alone (or don't have a bolt) and you just work with it as a unit.

idk maybe im super wrong and it will blow up now. but in time is in time from my perspective and I got it dead nuts.

 

Rebuilding notes:

Pistons have been marked as to their location (cylinder #) and ALWAYS note the directional arrow on the piston dome….it MUST be installed with the arrow pointing forward. Failure to do so will lead to significant and potential catastrophic engine damage and/or failure.

Always lubricate the cylinder bores and pistons/rings fully with a high-quality assembly lube or 30W engine oil during installation.

We offer piston/ring installation tools for rent if you do not have the proper ring compressor available.

You MUST following the factory-recommended procedure, values, and tightening sequence when installing your cylinder head. THE #1 CAUSE OF HEAD GASKET FAILURE IS DUE TO IMPROPER HEAD INSTALLATION PROCEDURES!

We also recommend that the cylinder head nuts be checked and re-torqued (IN THE CORRECT SEQUENCE!) after 100 miles and 500 miles.


The factory advises the following break-in procedure for re-ringed engines:

For the first 500 miles, no more than 1/3 throttle should be used and engine speed should be varied as much as possible within the 1/3 throttle limit. Prolonged, steady running at one engine speed, no matter how moderate, is to be avoided, as well as hard acceleration.

Following the 500 mile initial period, increasingly more throttle can be used but full throttle should not be used until after 1000 miles, and then it should be limited to short bursts until 1500 miles have been logged.

Mono-grade oils are recommended for break in as it provides a better bedding pattern for the rings and cylinders than a multi-grade oil can.

During the break-in period, oil consumption will be higher than normal, and frequent checks and re-topping of the oil level will be needed. At no time should the oil level be allowed to drop below the bottom line on the inspection window in the clutch cover.

It is essential that the oil and filter be changed after the first 500 miles (note: I prefer an oil change after 100 miles and then again at 500 miles). It is also a good idea to change the oil again after the 1500 mile break-in period is accomplished.

Although not mentioned by Yamaha, I also recommend that the cylinder head nuts be checked and re-torqued (IN THE CORRECT SEQUENCE!) after 100 miles and 500 miles.

 

The reason for removing the cams in the way that is in the book is the original cam chains are endless. Removing the cam sprockets allows the cams to be removed without breaking the chain and then having to fit a new one. If your machine has a cam chain with a master link, then removing the cam sprockets is unnecessary.

When you go to recheck the head nuts you must loosen them in the proper sequence, and then retighten in the proper sequence. Just putting a torque wrench on them will give an innacurate reading and can lead to overtightening. Just tightening any loose nuts can lead to uneven clamping force being applied, and may result in head warpage.

 

My chain is stock and endless and I did not need to remove gears. And all my other bikes are endless and I have never had to break them to get cams out. Once the tensioner is removed and cam caps there is enough slack to free the intake and remove. With that gone exhaust is easy.


Install exhaust first. You have to think about how it will rotate when tightening. Tight on exhaust then pull slack out. Then install intake. Tighten cam caps. Everything rolls into place. Then tensioner install


That was probably unnecessary and over explaining and didn't help much. My observation was I have not been asked to remove gears on anything else but typically I don't work on things this old. And I also don't work on every engine ever made, so maybe it's more common than I am aware.

 

Interesting. I'd think that would make it a bit tricky (for me anyway) to get the cam timing correct.
If it works for you, do it.

 

while it was just for my own knowledge and really didn't need to, I bought a quality compression gauge. and I much prefer its numbers 150 across the board.

up to a whopping 75miles on it now. I really need to find time to ride more.

 

As an aside, I tried your method for cam installation this week, and found that there is not enough slack in the cam chain. I was able to lay the exhaust cam into place and set the timing for it with the sprocket in place, but had to remove the sprocket from the intake cam in order to get into place and have the timing for it be correct. It could be that your cam chain has more slack in it than mine does.

 

You don't set the intake on journals then pull this chain over it and on.

You put the chain on the intake cam and lift and roll into place. So you have to think how it will land maybe take a couple tries. So you do chain and cam install in one go. Not cam install then chain. As for stretch I feel mine is properly taught but it is original and I didn't measure it.

 

this probably doesn't help much, but here is an excerpt from one of my YZF manuals

 

and against those instructions, I typically get the exhaust where it needs to be and bolt down the cam caps to help hold things in place. that way I can pull against the cam to keep that chain nice and tight then align the intake and take into account the slight roll that happens when tightening the caps, but usually its pretty obvious how it will land. on the XJ I got in it one go.

I have used the method 10-12 times on various inline 4s but all sport bikes until the XJ (that's where my experience mostly lies)

 

I tried that too. Didn't work for me. It might could work for someone else though.

 

Like 300 miles now. oil changed at 100 something. All seems well. Thanks all.


Kmoe , the timing thing still on my mind. You had your tensioner out when you tried right? Idk I need to let it go but it bugs me.

 

I did have the chain tensioner out. It's the last thing I install before spinning the engine to confirm timing.

I'm not saying that your method doesn't work, it just doesn't work for me.
In the time I spent trying to get the cam to roll into place I could have had two engines timed, and I think that probably just says more about me being well practiced in a particular method, than it does about the suitability of what you do.