AIRHEAD VALVE ADJUSTMENT with Pics

I just write them in a notebook or notepad

 

I wish I was organised enough to do that.
I even write the tire pressure under the seat.

 

I'm going to keep a spreadsheet with measurements.

Shout out to Len (Chacal). I ordered the proper shims and other parts on Sunday night. They were waiting for me when I got home from work Wednesday. Saturday will once again be a project day to bring my valve adjustments up to spec.

This site is great! I encourage others to join as a paying member. I figure I've saved hundreds by learning to DIY from here.

4/30 - swapped in shims today. Took 3 hours. Bike has nice 'tick tick tick' again.

 

This was was a big help to me! I was afraid starting the job, but eventually it was easy and very satisfying! Thank you so much!

 

I have a question, I'm very new to the world of xjs and I bought a basket case of a bike. I was wondering since my engine is not timed (timing chain is disconnected) could I remove the valves completely and do a bench check on them or would I be better off leaving the valves on the engine and rotate the cams by hand, the po rebuilt the engine but never timed it, when I got it I had 5 shims and 4 buckets in a bag with 4 buckets only 3 with shims on the valves with the cams removed

 

You are better off carefully setting the cam timing with a new chain, otherwise you risk damaging the valves when they hit the pistons. Put the shims in the buckets so they don't get damaged. Doesn't matter which shims go where, but you will be swapping them around to get clearance measurements. You might consider buying a full set of the plastic shims that Chacal sells for shim swaps.

 

Thanks moe I will set the timing tomorrow befor I check the clearance. It has a new chain in it but the cams were out of the engine so I'm going to have a little prepping to do there. Is there a downloadable service manual anywhere I was going to pick one up tomorrow but I doubt anything will be open

 

Does anyone have a link to a good set of feeler gauges that will work for valve adjustment needs?

 

Yes. KD Tools 2274. Any decent auto parts supplier will have them.

 

I do....actually I have two sets---the'yre available at Advance Auto Parts ,and many others----

 

I now keep them in a sandwich bag with a bit of oil. The gauges started to rust...

 

Hello everyone, i have a few questions, first i hear that yamaha ( from a dealer ) shims are best compared to online shims is this true ? second lets say all is good timing, valves, sync. when/ how and why do you adjust the m( im not sure what you call them ) screws on top of the carbs that you start out at 2 1/2 turns ? Last Q, if you have 1 cyl, that is lower on combustion than the rest do you sync the others to that cyl ?

 

I think you need to start a thread for your bike. Put these qustions in that thread, as the answers will likely lead to you having more questions.

 

my bad. will do.

 

I have a 1982 xj 750 j maxim. My first question is i hear that yamaha ( from the dealer ) their shims are better than online shims is this true ? Next on top of my carbs the screw that you set at 2 1/2 turns out to start, then adjust... when do you adjust these? and how do you know if you have adjusted them right? What are the things you do before you start to adjust these screws? last Q If you have 1 cyl that is lower in combustion than the others do you use that one to sync the other carbs to?

 

if you want to pay 28$ for shims at the dealership go ahead,the after market shims are 8$ my dealership sells both.
problem is I have to buy the aftermarket shims in a 5 pack. so if my dealership sells both which is better?

I pick up new bmw shims when I see them on ebay.
there is a shim pool here of used shims which all work well.

the syncing is done to the lowest power cylinder

you can buy a color tune to adjust the mixture screws, or read the spark plugs by doing plug chops and adjust the screws. a temp probe works too.
you want your plugs to be paperbag brown.
you can adjust by ear if you want
as to when, you adjust screws sync ,adjust screws then sync .........

if you start your own thread in the tech forum we can go into detail about your bike and what you need to do after the valve adjustment

 

Thank you for this info my new friend, look for me in the tech forum.

 

Thanks for the thread. I took all of my measurements and so forth... then realized it's 30*F outside. I know you shouldn't check the clearance HOT but how cold is too cold?

 

Well... I believe the engine internally needs to be under 92 f , but I've never seen a minimum temp...... but I would think if my hands are too cold, I would wait till they are a bit warmer, and the metal isn't too COLD to touch--- lol

 

Great how to do the shims Fritz thanks.

 

As a rule of thumb, steel expands (or contracts) at a rate of 0.001 inch (0.0254 mm) per 100 degrees Fahrenheit. So checking the valves at 30ºF instead of 60ºF will not matter enough to cause trouble.

 

Does anyone know the highest mileage an XJ engine has done without an overhaul? What is the average life of a timing chain on the XJ 900f? My bike has only done 34000 miles.

 

You mean engine tear down?

I know of some reports over 100k..... my first 650maxim now has close to 60k on it.

All of my runners have around 30-35k......

Take care of clearances, oil, and keep carbs clean..... you'll not have to worry about tearing the engine down

 

I know of an Ariel from the late 30's that ran for almost 160,000 miles before an engine rebuild. Now add 50 years of improvements to engine manufacturing practices and oil characteristics.

 

Yes Hogfiddles I meant an engine stripdown. As you say routine maintenance is the best way to protect the unit. I have still to check my valve clearances but I cleaned the carbs as the engine would not idle when I got the bike now it's running great. Which oil do you recommend for the XJ. I used to use GTX years in my CB 750K2 (should have kept that bike) but not sure if that is ok for the XJ 900f. Yes k-moe that is a great mileage perhaps it was a Square Four? Going to change the oil and filter every 3000 miles anyway and next job is checking the shim cam clearance.

 

I use Yama - lube 10 W – 40 in all the bikes, all the time

 

See link in kmoe's signature about choosing the right oil for wet clutch motorcycle. All the stuff and more.

 

Stumbled across this thread and was very curious as to when it was recommended to check the shim clearances.
My 1982 750 has a minimum of 200,000 k on it and I am sure its over 300,000. The original owner ( I am second owner) told me he put over 100,000 k on it. I have turned the 5 digit odometer around twice myself.
The only work thats been done is front and rear brakes once and a set or two of spark plugs.
Oh and of course my awesome hand built custom exhaust.
In my opinion if its not broke dont fix it but dont want to have any unseeen catastrophic failures waiting for me.

 

Checks should be performed every 5,000 miles. Adjustments as-needed.
Not checking or adjusting the valves WILL cause things to break.
The first sign of trouble is usually difficulty restarting the engine when it's hot, but sometimes the first sign of trouble is a valve head snapping off and dropping onto the top of a piston and the engine making funny noises until it stops running.

Do you hear the valves ticking? No? Then they are in dire need of adjustment.

 

You should be able to hear them tick?
I would have thought a ticking noise would be a bad sign. lol
Thankss

 

Ticking means that there is clearance betweeen the shim and the cam so that the valves can fully close.
A short list of combustion engine valves that should be silent: Rotary valves, Reed valves, valves actuated via hydraulic lifters.

 

At 200,000 mi, your valves are at their scheduled 40th valve shim clearance check.

When you finally DO get them back in spec.....and then get the carbs back to where they belong-----you're right gonna find out just how much power you've lost along the way and don't even know it. She'll scare you all over again

Dave

 

I will try the Yamalube 10W40 thanks.

 

Sounds awesome.
Now i just need spring to arrive and maybe somebody to lend a hand. Never done either of those tasks before.

 

Is it absolutely necessary to replace the shims after you check the thickness? A local bike shop will trade me shims but they need them the same time I pick up the new ones. Will I damage the cam/buckets if I take all the shims out at once?

 

I'm glad you asked! Don't pull out the shims and rotate the cam on the buckets. I almost did and the guy who runs the shim pool here advised me against it.

 

Ok. I really Hate math.
Measured my valve clearances today. My feeler guages increase in .05 mm increments. A 0.15mm feeler will not fit in on the intake side but a 0.10mm will. On the exhaust side a 0.20mm feeler will not fit but a 0.15mm will.
My confusion starts here. If the clearance was for example 0.104mm and the shims are only available in 0.05mm increments when I add any shim it will put me out of spec on the loose side.
I am kinda lost as what to do. Should I just leave well enough alone?

 

You're going to need tighter gages, hate to say it. The whole tolerance is .05mm. You have no way of knowing if you're in or out of spec with your current gages.

::Edit:: You can do it with .05mm increment gauges. I wasn't thinking it over properly.

 

I was thinking the same.
However.
What still makes no sense to me is if the shims are only avaiable in 0.05 mm then the valves cannot even be shimmed into spec unless the clearance is below 0.010mm

 

That's correct. In spec is in spec. Out of spec is out of spec. When you get to .10, you shim to .15 and you're in spec.

 

Look at the table in the first post.

Also note that most metric feeler gauge sets come with thin brass feelers that are meant to be stacked with the other feelers in order to make a gauge that is between the 0.05mm increments (e.g. stack a 0.01 onto a 0.10 to make a 0.11).

 

You NEED TO Have a feeler set that you can measure what the CURRENT and EXACT clearance is at a stone cold temperature.

You also need to check the size of each CURRENT shim.

NOW you check the chart..... match your current clearance with the current shim.

If ANY intake clearance is ANYWHERE between .11mm - .15mm, you're in spec so leave that one alone.

If ANY exhaust clearance is ANYWHERE between .16mm - .20mm, you're in spec so leave that one alone.


You really don't need to do any math. Just triangulate the two lines on the chart. We just call it"doing the math".

If you need more help start a conversation with me and I'll check your numbers for you.

Dave f

 

Actually the tolerance range is only .04mm.....

 

It's .05mm. .11 is in spec and .15 is in spec, which makes it an inclusive series, so you have to count both numbers with three in the middle.

 

I guess it'll depend on how we want to look at it.

I see it as:
1-2
2-3
3-4
4-5

And for exhaust :
6-7
7-8
8-9
9-0

But none of that really matters… In spec is in spec

 

I like that. Now, is zero a number?

 

Yes. The origin. Number lines, graphs, and such.

 

Just checked my valve clearances.

Minimum of 200,000 km on my bike.
I am the second owner. Original owner turned speedo over 100,000. I have done it twice myself.

Here are my shim #'s.
Oh BTW. Have never checked or replaced since I owned the bike.

Intake #1 0.15. #2 0.13. #3 0.13. #4 0.12mm

Exhaust #1 0.17 #2 0.17. #3 0.203. #4 0.17mm

 

Personally, I find that not believable at all. 300,000km ( "Original owner turned speedo over 100,000. I have done it twice myself. ") and almost all shims still above the middle of the tolerance range---riiiiggghhhhtt.