AIRHEAD VALVE ADJUSTMENT with Pics

A Magnificent "Do-it-Yourselfer" ... Gloriously Illustrated with magnificent photographs.

 

How do you get the rubber washers out of the valve cover bolt?

 

It's a pain, but you should be able to just cut the old rubber section off, leaving the metal top. Then you should be able to muscle them off... I used an exacto knife...

 

I cut the whole works using a heavy wire cutters, then twisted them off.

 

+1. Just CHOMP thru them with a big pair of diagonals and twist the remnants off.

 

:wink: does anyone know the specs for the 400..would i be following the same steps only for 4 cams instead of 8....i don't have a manual and i can't find one anywhere! it's been driving me crazy try'n to get one...i'm still far from doing this to my bike..but just needed a heads up..what i need to pick up for this uber fun job... :wink:

 

If you're talking about the DOHC 400cc twin YICS "half an XJ motor" then you are in luck.

Except for actually accessing the valves, everything else is the same, just half as much work.

I have a copy of the "multilanguage" (yes includes English) service manual for the XS400 "Seca" but mechanically the XS400 Maxim is the same. The problem is, it's 71MB compressed. PM me with your email address and we'll see what we can figure out; maybe FTP or I can burn and mail you a CD.

 

Perfect guys,

Thanks a ton. I think I know what I am doing now.

Dave...

 

Dear BigFitz52, I am 56, this 1993 XJ 400 is the 21st bike I own, and will hopefully be the first one I will do the mechanical job myself.
The upper part of my engine is sounding really clunky, so I intend to begin checking the command chain. your tutorial on valve adjustment is wonderful . At a certain point you mention "a tool" that must be screwed to the head, supporting the cam shaft:

"Place the "tool" in position, ..."

Is this a specialized tool that is sold... where?

Finally, I wonder if there is a similar tutorial to check and replace the command chain?
Thanks, Aharon

 

Do you have a 4-cylinder 400?

If so it is very similar to the 550s. Your camchain tensioner is an assembly that sticks out the back of the cylinders, in the center below the carbs.

If it is the manual-type adjuster there is a locknut and bolt on the right side of it. It looks like this-- All you actually see is the body and the adjusting bolt if it's that style, everything else is inside. (Ignore the arrow in the pic, that was for something else.)



Adjustment is as follows: Remove the ignition cover as shown in this thread; and position the pointer to the "C" position on the plate.

Using a 12mm deepwell socket, loosen the locknut on the adjuster bolt. Then using a 10mm socket, loosen a couple of turns but do not remove the adjuster locking bolt. When you loosen the bolt you will probably hear a "click" as the adjuster takes up slack. You may not, no worries. Re-tighten the bolt to 6 newton-meters (51.6 in/lb) then torque the locknut to 9 newton-meters (78 in/lb) and you're done.

If you DON'T have a bolt with a locknut on the side of your adjuster then it is the "semi-automtic" type and I'm not 100% sure on that procedure as all my XJs have the manual tensioners.

The "tool" is Yamaha special tool #90890-01245-00, commonly known as the "Yamaha valve shim tool." It's readily available from almost any aftermarket motorcycle parts supplier like Bike Bandit, you can find them on Amazon http://www.amazon.com/VALVE-SHIM-TOOL-Y ... B000UKIT8U and XJ4Ever (link on the banner in the upper right) carries them as well.

You can also use a piece of #12 insulated electrical (house) wire with a hook on the end, shove it down the plug hole and hook under the edge of the valve to keep it open. I personally do not use or advocate this method.

 

Thank you bigFitz! As you can see, I have found my way through the "search by author" resource.
Yes, it's a 4-cylinder 400, black and beautiful.
Your advices are great. My bike's tensioner is like the one in the photo. I left all my tools in Brazil (why lug so much iron anyway...), so I will buy new ones here and begin filling my nails with grease - gotta love that!!
Great hint about "the tool"! I believe I will find it in Tel Aviv.
Aharon

 

i was thinking of trying to do a valve job on my 81 650 maxim, but i was wondering where you got that "tool" that you bolted on that you used in your pics
thank you

 

i was thinking of trying to do a valve job on my 81 650 maxim, but i was wondering where you got that "tool" that you bolted on that you used in your pics
thank you

 

Mike: First off, that's not a "valve job." A "valve job" involves pulling the head and renewing the valves (replacing or lapping) and valve stem seals, etc. A real teardown.

We're talking about a simple valve adjustment. A maintenance procedure.

The "tool" is commonly available from almost any motorcycle accessory shop, online, Amazon.com, and chacal (XJ4Ever, see link in banner at the top of this page or http://xjbikes.com/Forums/viewtopic/t=14561.html ) also carries them.

DO NOT pay $75.00 for one, they go for around $20 or less. (I saw one online the other day for $74.99!!!!)

Scroll up about three posts in this very thread and I posted a link to a pic of one.

 

Very nice write-up! This job is on my list for winter-time projects on both XJ bikes. (You wouldn't happen to have a write-up done for checking valves on a KLR650? That's on the list, too.)

 

think I need some new shims?!
Intake: 0.076 0.051 0.051 0.051
Exhaust: 0.076 0.178 0.076 0.155

I couldn't believe how tight most of these were. seems like only 1 of the exhaust shims are okay right? (.178)

 

personly I think that tool is a waste of money I like the copper wire method and tiny flat tip screwdriver, tool slips off too easy however you decide to do it wear safety glasses

 

so i got my numbers! i simply used a wire method to keep the valve open and with a tweezers was able to eventually get the little boogers from underneath the camshaft. whew went ahead and discovered all eight shim sizes and will be replacing 7 of them.
Fitz, without this write up including pictures I would have never understood this. also, thanks for your second part demonstrating the wire method with an extra piston head. helped tremendously understanding!

 

bigfitz, thanks so much for this write down...
I'm working on the X model, but it helps me to understand a lot of the technique.. My only challenge will be to remove the cam's.... Wish me luck

 

I just did it with the tool and didn't have a single issue with it slipping off. As I was doing it, I was wondering how it was possible for it to not work 100% of the time.