High mileage stuff

My bike is almost at 60k miles, and it's time I did something about that. I've got a few maintenance items lined up before uni starts back up in the fall:

- New head gasket (it's actually leaking at the head, not the valve cover gasket)
- New cam chain
- New cam chain guides (if necessary, I'll post pics once they're out)
- Rebuild/reset the tensioner
- New oil+filter, light carb cleaning, valve adjustment, sync, colortune, etc.

After doing a bunch of searching on the forums here, I've also learned of a few more jobs I can/should do with the head removed:

- New cam chain tunnel gasket (why is this so $$$)
- Clean/decarbonize everything
- Lap the valves, new valve stem seals

Most of these items are just straightforward replacements, but I have a few questions about procedure, mostly about lapping the valves, since I've never done that before.

- Can I rent a valve spring compressor tool from an auto store, specifically the "clamp-style" compressor that is used for our bikes? I don't really want to buy one just for this job.
- What kind of valve lapping compound(s) would you guys recommend?
- Any recommended tutorials on how to actually do this? I have a factory manual which does go over this procedure, but any practical advice from those who have done this would be appreciated.

Thanks in advance!

 

Since preventive maintenance is based on knowing when to intervene before something breaks, I'd also like to hear others' opinion on the longevity of alternator brushes and chain, oil pump chain, and any weak points in the starter system. Any of these might be a real "trip-killer" if they fail far from home, so I'm wondering what intervals are appropriate as my bike gets older.

 

The factory claimed alternator brushes needed to be replaced every 10K miles. One of my 550s is at 27K miles and the alternator brushes aren't worn to the lines yet. I may replace them simply because of age, or to be proactive at 30K or so.

In the shafties (650/750/900) the only real "Achilles' heel" is the "primary" chain guide/tensioner. It's known to disintegrate at some point and the chunks get caught in the shifter forks. The chain itself is not known for wearing out.

Cam chain and guides at 60K is probably prudent, as are valve stem seals and a quick touch-up of the valves (lapping) if the seats are in good shape.

 

Would that be the cause of the few cases I've heard of a transmission being "stuck in gear?"

 

Sure would. Do a forum search and you'll find a number of reports. When it happens, it's often possible to reach in through the access hole above the shifter mech and pluck the big hunks out so you can shift gears again. The real fix is to split the cases and replace it.

There seems to be no particular set of circumstances or conditions that cause or can prevent this; although it doesn't seem to happen as often to lower-mileage bikes. It may have to do with the number of heat cycles it went through prior to its hibernation, the number of heat cycles it subsequently gets put through when the bike gets put back in service, the condition of the oil it had in it when parked, dunno. There seems to be no real common factor except that it happens with alarming regularity.

If I ultimately decide to keep my 650 long-term, I'll pull the motor and replace the damn thing rather than have it fail halfway across the Continent somewhere. Luckily, the 550s are designed completely differently and don't suffer the affliction.

 

Is a better-quality replacement part available, or is OEM through Yamaha the only option?

 

I suspect (and fervently hope) that the currently-available replacement is made of a more modern, higher-quality plastic than the original. I would NOT recommend an NOS part.

That's a "chacal question."

 

Yeah, that would be a big investment in labor to do nothing more than "reset the fuse on your time bomb!"

 

A couple more things if the motor is all apart -
Replace shifter springs
Inspect / renew the starter clutch
Put a magnet in the sump - I place magnets on my oil filter and you should see all the crap they collect.
Gaskets at shifter and output shaft.

 

Back on-topic:

I've made these for different model engines by bending a short piced of "band-iron" into a "U" shape and using a big "C" clamp. Have not tried this on an XJ cly head, but it's worth considering for a one-shot project.

I've always bought whatever my favorite auto-supply store carried. The name "Clover" comes to mind. Generally there are 2 grades--course and fine to be used in progression. It's less important what brand you buy than it is to flush it all out with solvent and compressed air when you'te finished.

I like any cheap suction-cup tool, but a short piece of rubber tubing can be hose-clamped onto the valve stem for spinning from the "top" side of cyl head. It's important to keep lifting the valve off the seat to work fresh compound back in between--only a small amount of compound is needed, but it is quickly ejected and needs to be constantly smeared back into the joint.

When finished lapping, you need to check the seat width with some dye paste. If it exceeds maximum specs, you'll need grinding or cutting tools to relieve it above and/or below the seat.

Anybody with the skills to remove the cyl head will find lapping to be a simple job. I can't recommend a tutorial, but a web search should find a number of these.

several edits for spelling, etc.

 

This was really my main question. I checked my local auto parts stores online and all they seem to have is the Permatex Valve Grinding Compound, which doesn't indicate any kind of grit value. I thought I needed a fine grit and separate coarse grit compounds as you and many tutorials have said.

I'll have to look around at a few other parts stores if they have the correct tool to rent. I've made a few tools for working on the bike, like a manometer and the yics block off tool but I don't think I feel confident making a tool to do this.

Thanks for the advice, more Q's and pics will come when I get the engine apart.

 

I've always had two grits available, but not convinced this is absolutely critical. IIRC, even the course grit leaves a good enough finish that it could be assembled and run as-is but may take a little longer for the surfaces to burnish themselves during break-in. The fine grit would be noticeably slower at removing metal during lapping process. Maybe your parts stores are selling something in between (call it medium) that should be suitable. Permatex markets good quality, and standard valve-lapping practices prevail among 4-cycle engines, auto or cycle.

edit to add: In a recent conversation with an old-school Yamaha dealer from the '70s & '80s, he reminded me how important it it to check valve lash on these bikes after break-in of a new engine. That would apply to a fresh valve-lap job as well.

 

I definitely plan to adjust the valves after all this, as they'll probably be out of whack after the valve lapping. They are probably due for adjustment regardless.

It looks like it's time to tear it down. But before I do that, I think I'll post some pics of my bike, since I haven't done that yet!



Click for full view:

 

Of course the clearance (lash) will need to be reset during re-assembly. My point was that it's prudent to check them again at break-in intervals similiar to a new bike, because they may further seat themselves during run-time after the lapping.

 

Update:

I'm just about to remove the cams. I have the cam sprockets off and I just need to remove the cam caps. The problem is that I don't know the exact order to remove the caps/bolts to prevent any damage to the engine. The #2 intake cam lobe is currently pushing a valve open. Should I start by removing the caps further away from that lobe? I imagine that the valve spring is putting quite a lot of upward force on the cam lobe / shaft, and I don't exactly know how to handle the

The manual doesn't say anything about this--but then again the manual also states that it is not a substitute for a general mechanic's education. I guess this is just one of those knowledge gaps?

So, what order should I remove the cam caps / bolts, given which cam lobes are pressing down on a valve?

 

As general mechanic, , here is the method that will be correct most of the time.

Break each nut loose, and then start at the center, and use a criss cross pattern, loosening each nut a quarter turn. Sort of like head bolt torqueing, only in reverse.. It will take a number of times, but you don't end up causing undue stress on the cam. The same method is used for tightening/untightening the bolts on clutch plates. CZ

 

What have I done!?


This is really dirty!



The tops of the combustion chambers. The other two (not shown) are extremely similar to the ones in this pic.


The lighting is poor on this one, but if you look closely there is definitely some wear on the end of this cam lobe (exhaust #2). There are a few others that have developed wear marks like this, but this one is the worst.


I have lots of questions now!

Once I get the head (valves) disassembled, it should be pretty straightforward to clean the combustion surfaces. I welcome any cleaning tips you guys have, as I don't think I can (or should) boil the whole head in lemon juice like I did the carbs!

But what about the tops of the pistons? I'm guessing that I want to avoid getting any chemicals and especially any dirt past the pistons. I assume the best (only) way to clean the pistons would be to start by removing the cylinder jugs, correct? It wouldn't be very difficult at this point. If I do so, should I consider new piston rings? Based on how well the bike ran before the tear-down I really doubt I have any compression problems, but while I'm down into the engine this far it would seem a bit of a waste not to do this. It could develop into a lot of work and $$$ though (going by chacal's piston advice in the catalog).

Also, what should I do about the wear on the camshaft? Anyone know what could have caused this? I really don't remember it looking like this the last time I adjusted the valves (~6 months ago, and certainly less then 5k miles).

I'll post pics of the cam chain guides once I can get some better lighting (daylight).

 

Best way is media blasting it, then parts cleaner and compressed air.

If you chose not to take the engine down further, then a wire brush and a shop vac will de-carbonize the pistons. At 60k, you most likely do have compression #'s that are low side, unless the engine was worked on before you got it. You need to measure the bore to confirm it is within spec. You can do the loan a tool thing with the local autoparts store. Measure the bore, and if is to the high side of spec, them it would be wise to renew the bore, pistons, and rings. If it is well within spec, then a good honing to give the cylinders a nice crosshatching will do, but do put in new rings of the appropriate size.

It would be adviseable to take the cams to a machine shop and have the surfaces polished. The wear is likely from metal particles getting between the cams and shims. Did you use a magnetic pluck tool to remove the shims? If so, they got slightly magnetized and will attract small particles of metal.

 

A little more disassembly:



I couldn't find the right tool to rent to remove the valves, so I ended up just taking the head to my local Yamaha dealer and had them remove all the valves and springs and whatnot. $40--stings a bit, but it's cheaper than the tool. I'll probably just have them re-assemble the head after I get it all cleaned up.

Upon closer inspection of the "valve area", I found a few wear marks that are a little worrying (click the thumbs to view a larger picture):



The picture in the middle shows what seems to be the worst wear mark, it's a noticeable scratch from the top which goes down to some horizontal wear marks. No equivalent damage to the corresponding bucket, though. The only thing that I can think of that I may have done to cause this was when I was trying to adjust the valves the first time--the tool may have slipped once or twice before I got the placement right, but I don't remember which valves this was on. But that's just a guess. None of the buckets show any real damage.

Going back to the rest of the motor: some of these exhaust side studs look very corroded. Do they just need a cleaning, or should I consider replacement [of them all]? All the sheathing around some of the studs was all cracked and corroded, and I've just cleaned them all off. Do I need to replace this sheathing? I don't have anything that could heat-shrink them onto the studs.



I guess the next step is to remove the cylinder jugs and pistons and send it all off to be cleaned up at a local machine shop. I'm also going to have lots of things measured, like the cylinder walls and pistons. I really hope I don't need larger pistons/rings. I doubt I have serious compression problems, but those parts really are difficult to find! Does anyone have any experience with aftermarket piston rings?

tl;dr: Scratches in the valve area, corroded/rusty studs, going to send engine parts to a shop for cleaning/inspection.

 

I've decided to not pull the cylinders. I originally wanted to, but I'm afraid this is becoming a little more work than I'd like.

That being said, I'm trying to remove & clean the rusted studs. I got one of them loose, the one in-between the 3rd and 4th cylinders on the exhaust side, but I can't seem to get the threads through the "dowel pin" around the stud, as there is still some corrosion on the inside keeping it from getting through.

Since the part is replaceable, I tried instead to remove it, but it is really rusty, and I may have messed it up on the outside a bit trying to get some kind of tool on it.



I hope I didn't mess it up too badly. I've got it soaking in kroil, I'll probably do that overnight.

Is this a pressed-in piece, or is it supposed to just sit there? What can I do to get this out?

 

I just got back from the machine shop!




Last week I had the cylinder head, cams, valves, and other top-end stuff taken to a local machine shop for a good cleaning and inspection (shout-out to Stradley's Machine Shop in Titusville). And now it's back!

I'm really satisfied with the cleaning. I also had them lap the valves while they were at it, so the valves should be really happy now. The mechanic said that everything looked good for its age, so that's good to hear as well.

I'm still trying to get that pesky stud/dowel pin out from the cylinder jugs, but once that's done, I can begin replacing the rusted studs and begin putting this whole thing back together.

 

Looks awesome. Keep us updated.

 

I finally removed some studs.

I ended up pulling upwards on the corroded stud while twisting it with a wrench, causing it to thread its way through the remaining corrosion.


(click for a larger view)

There's still a few more to go, however, and they're not the clean ones. Since all the rusted/corroded studs are on the front row, I am going to go ahead and replace just that row of studs.

Here's the problem: the service manual doesn't say anything about the studs. No installation/removal procedures, no specs for inspection, and no torque values (nothing that I could find, anyway).

Does anyone have any tips for installing new studs, like general torque specs, or if I should use thread-locking compound, etc?

Edit: Got them all out. The rest were much easier than the one I mentioned earlier. Time to order some parts and start cleaning this mess.

 

I've begun cleaning the surface of the cylinder jugs and I'm now worried that I've damaged it.


(click the thumbnails for full view, I didn't re-size them to preserve detail)

I've used sponges, plastic scrapers (which didn't phase the gasket residue), razor blades (which did), 80 grit sand paper (also worked, better than the razor), and gasket remover foam.

After searching the web I've found a lot of contradictory advice. I'm now worried that the razor blade and sand paper have damaged the surface of the engine. As seen in the pictures, there are lots of little scratches everywhere, but they are difficult to feel, ie they aren't very deep. Placing the razor blade edge against the surface where I used the sand paper doesn't seem to reveal any visible warpage. Maybe I'm worrying too much?

In any case, does anyone have any advice on how to clean this surface?

 

I don't use sand paper on any engine because the grit or abrasive can get into places you don't want it to. Just razor blade it clean and you will be fine. Blow every thing off good to get rid of as much grit as you can

 

that cylinder looks fine and looks clean enough already.
are the valves marked? once a valve is lapped into it's seat it should stay with that hole

 

If that was my head I'd have it milled, man that is rough.

 

I'm with The Wiz on this, with all the work you're doing, just bite the bullet and have the head gasket mating surfaces milled to ensure absolute flatness and clean-up anyd surface blemishes. Have the cylinder bores checked for size, roundness, and taper, and correct if needed. Have pistons checked, too.

Yes, you'll probably spend another $200 doing all that but that's less than $20/month for the next year, or slightly less than a couple of Micky D meals.........

Motor will scream once you're done! How's that starter clutch and hy-vo chain guide looking?

 

i'd like to see a better picture of those cams. how deep are those scratches?
do you have any way to measure the lobes?

 

You guys are starting to scare me now!

I changed my mind on pulling the cylinders because I was worried about needing new pistons. Oversize pistons for this bike are virtually impossible to find, and very expensive if you do. $200 isn't far at all from what I expected to spend to finish this project, but if those engine parts need replacing I'll be paying MUCH more than that, which is really my main concern.

But I suppose that's what I signed up for when I began all this work. I guess it's in my interest to go a little deeper, as I certainly don't want to do this again. If I take the cylinders off and take this stuff in to the machine shop, how's this for a worklist?

- Check piston diameter, cylinder bore/roundness/taper.
- At a minimum, install new piston rings and have the cylinders honed. I guess the wear of all the parts will determine if I have to use oversize parts, but if I do, I'm really in trouble. I've found some aftermarket standard sized piston rings for a curiously low price (anyone have any experiences with aftermarket rings?), but again, anything else = $$$.
- Clean the pistons (if re-usable), cylinders, and mill the top of the cylinder jugs. I had the cylinder head cleaned, does that need any more work?
- I might as well just haul the bike down to the shop and have them clean the base gasket mating surfaces as well, as I'm not so great with the whole cleaning thing.

(click for a larger view)

The cam lobe is pretty shiny so it's hard to get a good picture that shows the scratches, as any light reflection hides the scratches. They aren't very deep, I can feel them with my fingernail but that's it. For what it's worth, the guy at the machine shop said he'd re-use it, but if you guys really recommend it, I guess I could find a replacement. Last time I checked ebay used replacement cams can be had for a decent price.

Bottom-end already? Too soon man, too soon...

 

Bottom-end already? Too soon man, too soon...

Never too soon to replace that starter clutch, et al.

 

the lobe of the cam and the valve shim rely on a layer of oil to keep them apart while the valve gets pushed down. the oil doesn't get squashed out because there is no where for it to go, the shim is smooth and the cam is smooth and the oil can't move that far that fast.
yours has groves to let the oil squish into. the lobe starts touching the shim and bad things start to happen

 

I know, I just want to finish the top-end before I get started on another major task. I was having starter clutch issues before all this, but I was running full-synthetic oil in it, so I was hoping that I could buy some time by switching to a conventional oil.

So I should replace the cam? What I really want to know is how this happened. I never used any magnetized tools to adjust the valves or anything, so I don't think that could be the cause of the wear. How long does a camshaft last anyway? It probably depends on too many factors.

Any more advice concerning my piston issue? Or is there really no telling until I get it all into a shop and measured?

 

replace the cam? i would.
before you get into pistons, rings and bore and hone, you should step back and do one of those cost benefit things.

 

I removed the cylinders:





Time to take this stuff into the machine shop.

There was a lot of crud that fell into the engine. Not much I can do in the way of cleaning it, not without splitting the cases I guess. Which I'll probably have to do anyway because I dropped one of the piston pin clips into the crankcase, as well as discovered a noticeable crack in the primary chain guide.




If I wasn't way in over my head before, I certainly am now . Perhaps I miscalculated the cost/benefit.

 

Drop the pan & flush it through.

 

It's been a while, but this holiday weekend has given me a little bit of time to work on the bike.

I'm going to have to replace the primary chain guide, starter clutch parts, and other internal bits, so I'm getting ready to pull the engine. I disconnected many wires and removed the airbox and such. All I have to do is disconnect the drive shaft and the actual engine mounting bolts. Once it's out I can clean and inspect the frame.

Is there anything else I should do before removing the engine? Maybe take apart the clutch, alternator, etc? Any more tips for taking this beast apart?

 

take all that stuff off first, save the clutch for last. any bolt you turn is going to try to spin the engine and you use the trans and wheel to hold it back, plus it gets a lot lighter to pick up.
the u-joint flange is a pinch point for your fingers and that rubber cover, be careful there. last time i did one i unbolted the swingarm and wedged it back a little, much better.

 

slj64,

What you're doing with your bike is very impressive and quite encouraging. It takes some real "gonads" and or "t@ts" (for the ladies ) to go that deep into a rebuild w/o having someone(s) literally standing there giving you instructions. That is some of what makes this forum so dag gom great. A person can take a good platform non-running XJ and make that bike purr like a kitten, and keep it purring for as long as they chose to do so. And even tho I understand some of why these bikes don't have the market value that many of us think they should have, the knowledge and expertise you'll have once you put your bike together will be invaluable. So, cudos to you.

Gary

 

Hey guys, just stopping by to say I'm not dead! I've made some progress:



The clutch, alternator, shifter, and timing stuff is all disassembled. There are only a few parts left to remove before it's time to split the cases.

How hard is it to split/seal the cases, anyway? To be honest, this is the part that I am most worried about. That and gluing it back together.

I know you guys generally frown upon taking these bikes to a shop, but I've considered doing this just to have the primary chain+guide and starter clutch stuff replaced. I haven't talked to any local shops about this though, so I'm not sure they would even do it. I ordered some case sealant so I have the stuff to do it myself, I just really don't want to do this again.

I'm going to take the cylinder head in to a shop be reassembled soon, so maybe I'll talk to them about it. In the mean time, any advice on where to go from here?

 

You should have a Genuine YAMAHA Workshop Manual as a reference to guide you through Splitting the Cases.

If you decide to do a Split to replace the Primary Chain Guide; replace the Starter Clutch and Timing Chain while you have the opportunity.

Get a Large Cardboard Box.
Cut two large pieces of cardboard to use as "Bolt Organizers"
Use a Magic Marker and draw two Schematics of the Bolt Patterns as shown.
Draw and Number the circles.
As you remove a Bolt, ... jab a hole through the numbered circle where it belongs and store the Bolt where it belongs on the Schematic.


© Yamaha Motors Corp.

 

you did the hard part already, might as well go for it.
case sealer isn't a big deal, squirt your sealer in the corner of a baggie and snip the corner a tiny bit, then you can squeeze a tiny bead right where you want it.
what sealer did you get?

 

I ordered the sealant from chacal, it's Permatex MotoSeal Grey.

I guess my main worry is how easily the case halves will come apart after all the bolts are out. How sticky is case sealant? Any recommended points where I should apply a little "persuasion" to help split the cases?

 

once you get all the bolts out a few bumps with the heel of your hand should do it. remember the one hiding in the oil filter cavity.
sticky? my original stuff was like dried paint, not sticky at all. the new sealer, if it's like yamabond, starts to skin over as soon as it comes out so have everything ready to go and a helper is a good idea to get the shift forks in as you close the case.
go real light with sealer around the oil passages around the crank, you'll see that 99.5% of the sealer will squish out, so it doesn't take a lot. you want the surface dry and clean, no oil. go all the way around the bolt holes.

 

Exactky how and where to apply the sealant as well as a few other "non-intuitive" details are why we're recommending a factory book for this procedure.

 

Get the Genuine Factory Book to guide you through the Splitting.

Since you will be splitting cases, ... you should take this opportunity to do everything that might be a cause for needing to repeat the task.

Starter Clutch (complete)
Primary Chain Guide
Oil Seals
Timing Chain
Examination of Shift Forks

When you prepare to join the cases after completing the repairs and maintenance, ... CLEAN both Mating Surfaces perfectly clean.

Use New Safety Razors to remove any residue of previous sealant.
Cut 2-Inch Squares of a ScotchBrite Pad (Med.-Gray).
Moisten them with Isopropyl Alcohol and scrub Mating Surfaces to bare metal.
Finish Prep by wiping the Mating Surfaces with Cotton Tee-shirt Rags moist with Isopropyl Alcohol and let dry.
This treatment will let the Sealant BOND to the Case insuring an Oil Tight Seal.

http://www.walgreens.com/store/c/walgre ... la&adtype={adtype}&kpid=prod6056577&sst=36c0ba9a-973a-0848-7305-0000040fbafb

http://www.toolup.com/3m_7448_6x9-gray- ... 4AodjioAvA

 

these are the best thing i've found for gasket scraping, they lay flat on the surface and keep it flat, can't gouge the mating surface and they never ware out.
i've tried razor blades Rick, got more blood than gaskets
a machine shop should sell ya one for a few bucks

 

Looks like a great tip!

 

I removed the oil pump and the final drive gear stuff, except for these four screws:



They have been peened, and the manual offers no tips about how to get them out. What can I do to remove these screws?

 

Gotta use an impact driver with the correct-size torx bit........about the only way to get those out.