1985 XJ700 N Valve Check Time

Hi All,

As a new owner, I want to make sure I am doing things in the correct order. I've read bigfitz's valve check guide a few times, have a list, and some parts ready to order from chacal.

This bike was brought back to life about 5 years ago from being a seized engine mess. Runs pretty well now, even in 20 degree weather. The carbs have been cleaned annually by the PO (I know, how well? everyone is asking).

I figure it is time for a valve check before starting in on a carb rebuild/balance. Is it adviseable to order all new gasket and bolt pressure washers in advance, or wait to take it apart to see if they are on bad or good shape (Assuming they were last replaced 5 years ago).

If I start this weekend, and take it all apart, would it be terrible to leave the cover on loosely until a new gasket comes in?

Thanks in advance!

 

Typical advice would be to order it all new so that you can (without waiting) put it all back together and rely on it to be good for many years from now.

I did mine a while back and couldn't really afford everything, mainly because I was doing the brakes at the same time. So I ordered the valve shim tool, & a new gasket and took a chance. Turned out my gasket was basically new and the donuts still had some life. They are almost gone and I will replace them this spring, but no leaks.

So if you don't have to ride the bike I would get in there-check your clearances, the condition of your gasket and donuts, determine the shims you will replace-then order what you need at the same time. You might also need a gasket for the left front ignition cover since you remove that to turn the crank.

About leaving the cover on loosely-I'm guessing you mean would it hurt anything for the bike to sit inside and wait for the gasket. No harm unless you have little ones that will pull it off and put crayons inside. You definitely don't want anything foreign in there or on your cams, but as long as it's protected it doesn't have to be tight while it waits (but running it must be tight or you'll have a mess).

 

FYI - If you're using the shim tool, make SURE it is centered on the lobe from side to side; and once you get it there hold it down while you tighten the bolt. Bigfitz pointed this out in part II of his write up, but I didn't read that far and struggled with it a bit the first time I used it.

Also I had a sticky shim that just wouldn't release from the bucket so I created a tool (easy) to fix that problem and ease my future re-shimming. It works way better than a mini screwdriver. I was able to cut my time down by 2/3 to pull, read, and replace. More importantly the job is now zero stress and I won't gouge any metal with a slipping driver. Check it out below-it's just a metal "chip" puller that I broke in two pieces and reshaped. I also opened the angle a little on the shim puller at the tip. Should be able to find one at a computer repair store or maybe the Shack.

 

Well, I assume here that no matter what, because if I do have to replace shims, I won't know what size until I measure them all, and then they will have to be ordered. (Or shim-banked!) The bike is inside, so it would remain pretty secure.

Neat tools, Merc, I will get in there and see how it is, and maybe make a set like those.

I am suprised that there isn't a tool and shim set that can travel from person to (trusted) person for this job- it's not like it's an annual thing, is it? Maybe it is depending on how much you ride.

When I get my tool and shim set it, I'd be happy to loan it out to anyone who needs to do the job.

 

Several factors play into the frequency. How many miles you ride being foremost. How many miles on the mill, how hard you ride, and some motors just seem to need more adjustment than others. I believe a good rule to go by is adjust once, check again in 500-1000 miles (at least I will), then every 5,000 after that check and adjust if needed. It appears that once you get it in spec some don't move much after that.

Your idea is a good one and could use further inquiry. It would save money for the membership. If you are willing to pay the shipping round trip (less than $10) I would be willing to share my home made tools with you.

Yes you're assessment is correct, checking them is easy and will give you the info you need to proceed, they have a number printed on the down side indicating their size. The sticky one I had trouble with had it's number rubbed off so I visually inspected it under magnification and compared it to 2 known shims. If you have a digital caliper you could measure them that way. Below is a doc you could use for keeping track of valve work.

https://docs.google.com/?tab=wo&authuser=0#owned-by-me

Once you get your numbers post them as the curious want to know - how tight were they?

 

Recommended valve clearance check and adjustment interval on the earlier aircooled motors is every 5000 miles.

So it depends entirely on how much you ride; some of us end up doing it twice (or more) in a season; some of us annually or even less; again, depending on mileage.

MM is correct in that once in spec, after a couple of adjustments they tend to "settle down" and you usually find only one or maybe two each time (maybe even none) that need attention. But you still need to check them.

 

Off to remove the cover, we will see how it goes!

 

Dumb question, but all other fuel petcocks i've worked on had an "off" position. Mine has reserve, on, and prime. Can you just disconnect it, or do you have to plug it up with something quickly?

Never mind, apparently you can just unplug it.

 

Wow, those valves are.... tight. Real tight. So tight, that if the valves were a butt, and it farted, only dogs could hear it.

My smallest gauge is 0.0015, and it's tighter than that.

So I guess I have to get a whole bunch of shims and start experimenting?

 

No, you can "read" what's in there and make some educated guesses as to what you'll need. GENERALLY, a moderately tight valve will require going "down" one shim size; really tight valves usually mean two sizes.

 

Sounds good, I will do this once I get my tool in.

On the bright side, I fixed the sticky throttle issue the bike had. Gunk built up between the sleeve and the handlebar. A little degreaser, a thorough cleaning, a quick sanding, and some tri-flow later, the throttle works great.

 

Waah, I killed my XJ. :cry:

After replacing the head (my valve tool has not arrived yet so I did not actually adjust anything yet) it ran ok, and it was such a warm day yesterday, that I took it out briefly on the road. It ran great for my little 25mph jaunts up and down my dead end farm road.

Sadly, today, she won't start. before, she always started great, even on 20 degree weather. Now, not at all. I probably knocked some junk loose in the carbs and gunked her all up.

Oh well, onto the valve job next week.

 

Dude.

You've got to get some terminology straight here.

I highly doubt you "replaced your head" I suspect you mean you "replaced your valve cover."

And unless you're pulling the cylinder head, and removing the valves, cutting the seats if necessary and lapping them; you're not going to be doing a "valve job." A "valve job" refers to major cylinder head refurbishment.

You'll be doing a "valve adjustment." A regularly-required bit of maintenance.

It helps if we all speak the same language.

Speaking of valves, exactly how tight are the clearances?

 

Dude, you are correct, I make that mistake constantly. Like bathroom and kitchen, I mix those up all the time. I replaced the valve cover.

As far as clearances, it seems that the cams are actually touching the shims all of the time. I can't get a 0.0015 shim in there.

 

Then they're "dead" tight, and you shouldn't be trying to run the motor.

Assume two sizes down on all of them if they're all dead tight, and you'll likely be in the ballpark. One or two MIGHT be Ok with only a one-size change, although I doubt it, and 3 sizes is unlikely.

 

And to answer the question about the petcock:

ON and RES run off vacuum, so they will only let fuel flow when the motor is turning over creating said vacuum.

PRI is "prime" setting, for when the fuel bowl are drained (for cleaning, or when it's run out of fuel), will flow fuel at all times.

As you have found out already, if you pull the fuel line and the petcock doesn't flow in RES or ON, then your petcock is ok for now.

Sometimes the diaphram inside the petcock will fail, then it's time for a rebuild.

And I agree with Fitz, you do not want to run that mill until you get those valves adjusted.

 

My tool arrived, hooray. I am centering the tool on the cam exactly, and it does not hold anything down. Are there different size tools for different size engines, or do I just have to keep at it?

 

It takes a few tries before you get it in "the spot".

Make sure you aren't putting the tool into the notch for popping out the shim.

Once you find the right spot you'll be able to tell by the way the tool feels when it sets in the proper place.

 

Hang in there. (There's only one tool for the "airheads.")

You can see from this photo how the lateral positioning of the tool is the critical factor. If it's off at all, side-to-side, it won't "overhang" the edge of the bucket correctly and will miss the edge of the bucket when you rotate the cam away.

Getting to tool to work properly is a real challenge until you develop the "knack" for it; once you do, it works first time every time.

 

Got it. It turns out that my setup wanted the tool slightly off-center, inboard from the cam, and it worked great.

All of my shims are 2-70 (or Y270 which I assume is the same), excepting the #1 intake which is 2-75.

So I assume I need to get seven 2-60 shims and one 2-65?

Just for kicks, I suppose I could put one of the 2-70s in the 2-75 valve and check the clearances then.

also, ran across a few things:

1. A crack. I suppose I should replace this before it cracks apart and falls into the engine.



2. What is this very hard brown stuff??

 

Ok, you gave us all the shim sizes but you have to measure the current clearance between the shim when the bucket is UP, and the back side of the lobe when the lobe is pointing 180 degrees away from the shim.

Measure each clearance and write them down on a piece of paper
Keep track of intake and exhaust order
Now pull the shims and write down the numbers
do the math to get your new 'needed' number
swap shims
finish up.

Hard brown stuff? Looks like somebody broke the mounting boss and epoxied it back together. Kind of like the other one with the crack that wasn't epoxied. I think you'd better do something about them.

Dave Fox

 

Thanks Hoggie, I had measured them previously- I think they were touching all the time. The smallest shime, 0.0015, did not fit in 'twixt cam and shim. So I will be going down two sizes.

Somebody in this bike's past life apparently didn't know how to use a torque wrench.

 

Yea that's some poor re-engineering with an epoxy. Wishful thinking at best, not how it gets fixed for sure. They were obviously clueless about how the valve cover is held down, it's the rubber donuts that do the compressing and going tighter won't stop the leaks when your donuts have failed and your gasket is bunk.

I would def. try the measuring of your exhaust by putting that smaller shim in - at least you should be able to get a reading then.

 

Now here's the GOOD news. Those two cam "caps" are ONLY there to hold the cover and help keep the cam from moving laterally too much. They DON'T have bearing surfaces on the underside, so they can be sourced from a used head without any worries.

I'd replace them both.

Dave; read back up the thread. He couldn't measure his clearances, everything was dead tight; 'twas I who recommended he go two sizes down on all of them and re-check; with the caveat that one or two might still need to be re-adjusted afterward.

PO tracks. We've all been there.

 

Fitz, that must have been back on page one somewhere? I was just answering the post that I saw and hadn't gone all the way back to the beginning.

Yeah, going forward a couple shim sizes is a good idea here, but I think I'd recommend doing a complete shim clearance check a second time and do it from step one. Check, math, double-checking size replacements etc...... just to make sure since everything is right down to basically zero.

I'm gonna have to do that with the Maxim X that I'm building from scratch. The engine that I got turns out to have NO shims in it at all. So I'm literally starting from point zero on that one. Plus, being and X, I'm gonna have to do it the long hard way. Fortunately for me the engine is apart and on the bench. Still......the long hard way.

Dave F

 

If I swap shims for fun, when the shim is out of one, and I am rotating the cams around, is it okay for the cams to rotate onto and press down the cam lifter directly?

In other news, I took the rear wheel off today, the rear brakes are in okay shape- no delaminating, I tapped around the pads with a screwdriver handle to make sure nothing was going to fall off. The pads will last one more season, then it will be time to replace 'em.

 

Holy crap, I put the 270 in the 275 valve, and it's still touching. I think I might try to get a set of 2 sizes and 3 sizes smaller.

 

Hey Brocc...

I would not recommend pulling a shim out then turning more. The way I do it:

Check all current clearances and write them down
Next, pull each shim and check number, putting each one back
now do the math
see what shims can move to another cyl, order up the needed one
pull one and replace, go to next one and replace

I don't like the idea of the cam pushing directly on the bucket.

I'm sure there's either: 1. a good reason for that, or 2: absolutely no reason to worry about it but I still don't like it.

I have some that are quite a bit smaller...... think there's a 265, 260, and a 255 in my box.........

PM if needed

Dave F