Top End Rebuild - XJ650

Hello!

I was about to send carbs to another member here who does work on them. I was telling a co-worker about it, and he kind of went bonkers. ( He is a mechanic )

Anyway, long story short, I brought in my bike's engine for him to look at it. He noticed the head gasket was leaking oil, and kind of kicked my ass for not noticing it... especially before I was about to send carbs out. ( His argument was to get the bike engine working first and then worry about the carbs.

So, I need to do a head gasket on my bike, I haven't checked valve shims, but is it possible to do those with the bike head off?

Any advice for when the head is off as well?

 

I can't tell you whether or not you can do the valves with the head off, but I can tell you that it shouldn't take long to do, so you might as well just get it out of the way before you tear into the engine.

Here's the DIY:

http://www.xjbikes.com/forums/index.php?threads/airhead-valve-adjustment-with-pics.14827/

 

I suppose you could do it with the head off, but if the engine is out already, why not do it before you take the head off? I think it would be easier position the cam with the head on the engine and you would only have to take the cams off once and install once. With the head off, you would have to put the cams back temporarily at the proper torque in order to accomplish the measurements and shim replacement. If it was me, I would check the valves once the valve cover is off and note any that are out of spec, I would take out the shim and read each shim that is out of spec. Don't bother with the ones that are in tolerance. Just make sure you write everything down. Once you do this for the out of spec valves, I would proceed to take the head off. In the mean time, you can order the proper replacement shims so you can have them available once the head is back on so you can install these new shims. Does the bike smoke any when you start it? You may also consider changing the valve stem seals while the head is off. A set of Viton seals would do the trick. The biggest headache you my have is taking off the old head gasket. I first scraped off the big chunks, then used the 3m roloc (green scotch birte) with my drill and WD40. Best of luck.

 

Have the head face checked for straightness and correct if necessary..............

Check condition of valves, valve seats, valve springs, and correct if necessary........

 

When dis-assembling a component it is better to do adjustments and resets following the rebuild. A top end rebuild is something you must do correctly. Seek help if you are unsure of any part of it. Imo it is perfectly fine to have a more experienced person/member help you with the carbs. It would be better if you do the work and have the experience there to assist you as needed. The sooner you learn the carbs the better you'll be at trouble shooting and fixing potential problems. Lastly, you can't check valve clearance with the head removed. Hope this help.

Gary H.

 

How would you turn the cams to measure the shim clearance(s)? Like Gary said, you can't check valve clearances with the head removed. Period. Not being a prick to you Joe but just wanted you to realize this if you weren't aware of how/why.

In addition to the OP; has anyone done a test on the valves by a "leak test"? I'm currently in a similar situation with my XJ650 (yes I'm finally getting around to it!) and I found this quote by RickCoMatic over 5 years ago. Figure it may benefit the OP of this thread & myself if somebody can provide feedback on a test-check like this:

 

I did think about that when I posted. I don't know the answer to that. Not sure if it can be done. You bring up valid point which I did think about and maybe should have included in the post for consideration.

When I was considering sending my head in to have it refreshed by a shop in Orlando they were going to do the following:

Heat head and remove valve guides without causing subsequent damage to head.
Install new bronze valve guides.
Ream new valve guides to match valves.
Resurface valves using Kwik Way valve resurfacing machine.
Grind three angle valve seat to maximize valve potential
using Kwik Way valve seat grinder.
Lap valves into newly ground seats.
Trim valve stem length to match amount of change.
Assemble head with new Viton valve seals.
Install camshafts one at a time.
Adjust shim size to set clearance within specifications.

As you can see, a lot of what is normally done by a shop absolutely changes the lash and therefore requires reshimming as noted in the last item of the list. I don't know how they turn the cam, but doubt they strap it to an engine. Maybe with just one cam installed (and I would think the safe way is to do one cam at a time) the resistance is not to bad and wearing gloves while grabbing the sprocket can do it. Although I would be a little worried about my fingers. Or maybe shops use an old discarded cam chain to assist in turning it. Like I said, don't know, never tried it. Just assumed shops must do it somehow so I couldn't say it can't be done. But please keep in mind, in my original post I recommended against trying it with the head off.

 

I don't see why it couldn't be done with the head off, unless you feel the head is going to twist when it's torqued down.
Isn't there a hex area on the cans on the right side by the sprocket, that's what I'd use

 

both camshafts have a hexagonal flat section that can be used to turn the cams if the head is off the engine.

FU

 

OK Folks,

I loaned an O'reily auto parts compression gauge.

My Compression testing

Dry Testing

1. 110
2. 99
3. 110
4. 122

Wet Testings

1. 135
2. 124
3. 130
4. 134

However, The valve cover was off, and there was no oil filter on it. ( Not sure if that matters. ) As well as the engine hasn't been started in over 3 months.

I also ended up connecting my jeep's battery to the starter to get some cranking amps, since it seems my bike battery was shot.

Now, upon reading more, it says that O'reily gauges can be extremely off, and not known for accurate compression.
http://www.evolutionm.net/forums/ev...illy-autozone-loaner-compression-testers.html

So.. I think I'll buy a real gauge.

 

As well as, ( I should have added this. )

It was a cold compression test.

I was reading that engines generally get lower compression while cold. Yes?

 

regardless of the accuracy of the guage, you should still see consistency. that is, you should be able to recreate a cylinders compression numbers, regardless of whether or not it is reading actual psi.

you should also crank until the needle stops rising on each cylinder.

considering those compression numbers, you should also consider doing rings and honing the cylinders while you have it apart.

FU

 

One improtant thing to check before tearing the head off to replace the head gasket is to make damned sure that the oil isn't coming from a leaky valve cover gasket. A leak from near the cam chain tunnel will run down through the drains for the inner cooling fins and run along the head gasket, making it look like that is where the leak is coming from. As for the compression, get the engine running and re-check. Rings can, and do stick. A good run-in can loosen them up and you may end up seeing higher compression after that. If not, then you can start spending some time and money to set things right.

 

You most certainly CAN check valve clearances with the head off the bike.

That is exactly what the hex areas on the cams are for.

However, to do that, you'll have to remove the cams first so that you can remove the cam chain---- unless either your chain broke or you intentionally parted the chain .....

But YES, you CAN do it off the bike. The chain isn't what makes the clearance ..... It's the valves, buckets, shims, and clearance to the cams.

 

Are you dead sure it's the HEAD gasket? The VALVE COVER gasket can leak, and it runs down and around and LOOKS like the head gasket is leaking. I've also seen enough where the cam tensioner gasket is the culprit.

I'll go out on a limb, sight unseen, and say I'd suspect the valve cover gasket before the head gasket....

Dave

 

+1 on the valve cover gasket, along with the rubber compression donuts on the cover bolts. Fairly typical if the bike has not had the gasket replaced recently.

 

I checked around the valve cover. There isn't a drop of oil around it, neither in the channels. I checked around the tunnels and there is not oil. I'm 99% sure it is the head-gasket.

My friend's ( lets call him Danny, he is a mechanic at a my work ) agreed that the head-gasket is indeed leaking.

Nonetheless, my compression was lower. He plugged in his stuff and turned it over as well, results were very similar. The compression is indeed low.

I've started to pull off the head. ( Thank goodness for pneumatic impact wrench and getting the acorn nuts off. )

I also ended up pulling out one of the engine studs off since the bolt rusted / seized to stud. I'm soaking it in liquid wrench overnight and hopefully tomorrow I can separate it, and put it back in the block.

While the head is off, I'm going to remove the cylinder block and make sure that it is in spec. If it isn't I think it would be smarter to have it re-sleeved and aftermarket / oem rings.

As far as I know this engine only has 50 ish thousand miles. While on a car that doesn't seem like a lot, this motorcycle keeps me guessing with the abuse and wear.


This is my first motorcycle. I really enjoyed it while it was running... even if it was rough, and I think that I'll continue to enjoy it at years to come.

 

you know you can get a good running used engine for a couple hundred bucks. that's a hell of a lot less than rebuilding what you have.

FU

 

Would have been better check the valves before pulling the head. The low compression could have been related to real tight valve lash on those cylinders. A leak down test could have pin pointed that for you. If you decide to check the valve lash while the head is off, I would do it with only one cam installed at a time. That way the opposing valves will all be in the closed and there is no chance that you will have valves hitting each other when you turn the cam you are adjusting. Fifty thousand miles is nothing. How the engine was maintained is what counts. If you find you need to bore, you have the option of going with a first overbore or going to a larger performance piston kit. But even a first overbore entails new slightly larger pistons with rings. Personally, if the cylinders spec out correctly, I would only put new rings, give it a hone, check the valves for leaks and lap as needed, put new Viton valve guide seals, slap everything back together and check/adjust any valve lash . I like the minimalist approach. I would think you can get that all done for less $300.

 

The thing is.....oversize rings for an XJ are a rare (close to nonexistant actually) item, and custom rings cost $$$. The same goes for pistons.

Put the valvs in spec, button it back up, and re-test compression with a new head gasket. If compression dosen't come into spec all you're out is the cost of a head gasket. If it doesnt come back into spec than start shopping for a used engine.

 

Well, nonetheless, I started taking the head off last night.

I'm having trouble and not sure how to get the cam chain tensioner blade.

Also there are studs in the front / back of the engine, and on the same line of the cam chain track. Do those studs need to be removed to remove the head?

My haynes manual is somewhat lacking in details.

 

Front chain guide just lifts straight up and out. Rear chain guide stays in until head is lifted off, then the bottom retainer bolt can be removed.

 

I stand corrected although i'd still do it with the head in situ. It's a '81 650 right? Checking and correcting valve clearance from start to finish in situ - 1hr tops. Just saying.

Gary H.

 

Well, I finally pulled off the head.

These are the photos.



That stud at the top.. I broke. Nice! +5 Points!



Cylinder 4 and 3



Cylinder 2, and 1



And the the overall picture.

There seems to be an oil surface on the bottom of the head, and the head gasket looks to be in really rough condition.

I think this was a leaking head gasket.

Cylinder walls look nice and shiny though. I think ( but will have to check ) that the jugs are with in OEM specifications and they may just need to be honed + new rings.

 

Hopefully all you need is a hone and can reuse your rings, but now you need to figure out how much of the stud on #3 is sticking above the cylinder base mating surface, and hope you can get the remains out. Heat and penetrating oil are your friends. I was able to get all but one cylinder stud out of my original engine, but one just twisted and twisted. My only hope for it would be to take it to a machinist at this point, but in my case my engine is completely disassembled. Hopefully you don't need that much work.

 

I may replace the piston rings anyway. I called the local yahama dealership, and they may have some XJ piston rings. They're going to double check to see if they're for the 650. Apparently they were ordered for someone's bike not super long ago, and were never returned when the person decided to not put the work into his xj bike.

As for the stud, I broke a stud on the head of the engine. The stud that is missing came out with the acorn nut.

I'll probably buy a stainless steel stud kit and remove all the old ones and put in new ones for safe assurance.

 

First, don't spend any money until you know you can get the broken stud out. Pull the cylinders off and make sure it will come out easily. If it won't, you may be better served to replace the engine entirely.
Second, I would hesitate to use stainless steel for cylinder studs. Not sure what "kit" you are referring to, but the studs on these engines are proprietary and cannot be swapped with common studs. Stainless metal is typically not used for high-stress applications like a cylinder stud.

 

Note taken. I have a spare 1982 engine that I can pull studs from, even pistons if i need to.

 

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You most certainly CAN check valve clearances with the head off the bike.
That is exactly what the hex areas on the cams are for.
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that's exactly right , but beware
as "xjoe550" stated be sure to do it with only one cam installed, otherwise the valves will touch each other whilst turning the cam.
I bent 4 valves doing this, very easily without putting hardly any pressure on the spanner.
stu

 

So I contacted my local Yahama dealership.

I asked if they would measure the cylinders and make sure it is in spec to put new rings on my old pistons, slap it together and call it an engine rebuild.

They said it is $26.40.

 

Just hope they didn't mean $2640.00

 

Well, the guy said it would be "twenty-six forty".

Now I am one of the service guys at a car dealership right now. ( Short term job please! I'm young and want to get into the police academy. ) When the car salesmen say numbers to costumers they say "fiften, five, fifty" to make the number sound a lot lower instead of "fifteen-thousand-five-hundred-fifty".

Have you heard the story about the guy who dropped a socket into their engine? No? Let me tell you.

" Once there was a lad who was wanting to do an engine rebuild. He removed everything to the point of pistons and connecting rods. When trying to remove a stuck piston pin he tried tapping on it using a socket and a small hammer. ( While supporting the piston of course. ) He dropped it into the chain guide area, and somehow pushed it into line with the piston #2. By trying to retrieve it he pushed it into the oil pan. Once he removed the oil pan he was able to retrieve his socket. "

Well, now you have.

 

Dude, wad some rags into the throat of all 4 cylinders, and leave them there until you reinstall the cylinder block. Circlips love to fall down there.

 

Well. The yahama dealership charged me 27$.

Not a single cylinder was in service limit, but.. The pistons were not worn that much.

Decisions.. Decisions..

 

Well. Ok. I have a 1982 xj650 maxim engine to spare right now. I haven't jumped into it yet.

I'm going to check compression on that puppy and see what I need monday.

It may be more worth my time to say "balls to it" on this engine. Take the useful parts off of the '80 and rid myself of the rest. Then I'll need to figure out how to convert to an electrical tach. ( ASSUMING THIS ENGINE IS GOOD )

 

1982 engine looks very clean, and if I remember right the person who I bought it from said it was a runner, and was rebuilt at one point.
- 1982 had the lowest compression I've ever seen in an engine.

1980 engine rebuild / looking for new engine now.

 

If you are this far into it. Lap your valves and do your valve stem seals too. Might as well do it right

 

Alrighty, parts are ordered now.

New to me pistons and cylinders are in the mail, and they are guaranteed to be in service limits / specifications.

The build continues.

 

A few months ago I gave my friend Loren my motorcycle tank and side panels to paint. He has been working on them little by little ever since.

These are the results.






He ended up starting to sand it down because we assumed it had 1 layer of paint.

It had 8 layers of paint.

So my pal Loren decided to sandblast it, and he found rust holes. It also had been dented in on the left and right and was filled in with bondo previously. So he popped dents out, did a bunch of body work and repainted it.

The paint code is 6W, it is a mazda miata paint color. ( Laguna blue metallic )

 

Loren did a good job.

Gary H.

 

A good friend indeed!

 

Alrighty,

So I dropped cylinders and pistons off at the dealership for a hone + measure.

They said that #3 cylinder has a bit of surface rust that won't be honed out.

Besides that everything is fine. I think I'm going to soak the cylinders in diesel after they're honed, and then wipe them clean again so make sure everything is ok.

Apparently diesel will loosen any rust easily. That or the piston rings will just scrub the tiny bit of rust away too.

 

tell your friend he does real nice work, that's a pretty shade of blue. and ask him if he used a fuel proof clear on top.

FU

 

Well, I bought the paint with him.

So, when it comes to clear coats the generic, decent brands are all fuel proof after the clear coat hardens / cures.

Generally it seems the non-fuel proof stuff comes out of spray cans.

Nonetheless, the clear coat wasn't cheap. Altogether materials require for the paint was nearly $200.

 

very cool, just checking. truth be told, you can get fuel proof clear coat in a spray can, but you will pay for it.

FU

 

Yeah.

http://www.amazon.com/Spray-High-Gloss-Clearcoat-Aerosol/dp/B0043B7UQY/ref=cm_cr_pr_product_top

This junk.

I tried it on something a few years ago. It got fuel on it a day or two after and it melted the clear coat. I'll never buy that stuff again in a can. While this stuff is fuel proof after setting for a long time, most others aren't because they lack the activator.

We used some name brand clear coat and used it with a compressor and gun. It'll turn out much nicer and much better than a spray can ever could.

 

So.. Update time.

I have received everything I need, except cylinders that are good. I did find another new to me set without rust in them, with low miles. *wishful thinking*

I still need to mail the rust pitting cylinders back.

As for gaskets and such, I've received everything from Charcal. Now I'm slowly trying to remove 34 year old, 50,000 mile, baked on from the flames of hell, gaskets. I tried razor blades, and just couldn't get it off without gauging the metal.

So I opted for http://www.amazon.com/3M-08574-Gask...=1421914891&sr=8-3&keywords=3m+gasket+remover which is a gasket removal spinning disc set.
- Now it says to use an electric drill, but I found it hard to hold it steady, so I utilized my pneumatic tools and was able to attach one. I found that @75psi, this thing was batshit crazy and could rip though the metal pretty easy, but @25 psi
you could easy take off what you needed, without taking off the metal too.. I have been starting with the most abrasive one to cut through the hardest of the gasket, and then swapping to a higher grit later for finishing it.
I practiced on cylinder block mating surface and made them all shiny. To make sure I wasn't taking off metal I used a razor blade and shined a light behind it. So far it is working really well.
You just need to be very careful not to balls it up. Best $13 I have EVER spent on a tool.

Oh, and I picked up a complete exhaust system on ebay for $90. No rust, but a headpipe, and the crossover tube does have a small dent. Saves me from having to dick around with a mac exhaust.

 

That's what I use to remove gaskets Gurlok. But I had purchased a cheap knock off from Harbor Freight for around the same price. They are 3M roloc clones. But I only used the the red as the most abrasive and the green to finish. I first take off the big chunks of gasket by pulling and by scraping using a sturdy piece of thick sharpened plexiglass tool I made. That way, I can be sure I am not damaging the mating surface. When using the plexiglass tool and the roloc pads (with a drill), I would spray WD40 and let it soak a minute. I found this helped a lot. It gets absorbed by the gasket and expands it a bit, making it easier to take off. On certain new gaskets, I used copper gasket spray in order to facilitate removal the next time. However, I used a light film of grease on the cylinder block base gasket (this will make removal easier next time) and went try with the head gasket. All worked out for me. Good luck.

 

I received the incorrect cylinders today.

They had the YICs port, 1980 cylinders do not have the YICS port. >.>

 

That's right.... 1980 was a non-YICS xj650