Valve shim diameter

Hi All
Am working out what shims I need, but now can't remember if they are 25mm or 28mm diameter (or something else entirely!) - doh!
I'm away from the bike for a bit and was going to see which ones I need to get.
It is a 1984 XJ750
Cheers

 

Honda are 25 so they should be 28

 

29

 

doesn't matter what honda are.

the xj airheads are 29mm, as Polock said. (The Ventures have 25mm shims......and yes, I have a pool for them, too!----LOL)

29mm. But you can't just order 29mm shims.....you need to know EXACTLY what thickness you need. In order to do that, you need to have already done your clearance check, pulled the shims to record what sizes are already in there, and then have done the math or checked the chart to see what sizes you need to change to.

dave

 

Since we are on the subject of shim do any of you have a giant variety of them. I need a few under 260. I have a lot of 270s and 275s but no clearance yet.

 

29mm of course.
And sorry to thread jack

 

Hogfiddles How does one get into your pool ?

 

Just took a stab at size I know they where bigger just didn't want to go to toolbox and check for sure,was half awake at ungodly hour

 

Yep, I've measured the clearances, recorded the corresponding shim thickness, just forgot to check the diameter of them!
Just need to find 5 minutes to sit down and work out which ones I can shuffle around and what new thicknesses I need to get.
Thanks everyone.

 

Tell me what sizes you need, and I look to see what I have. No need to measure diameter..... They're all 29mm unless you have a maximX

 

is this done on a swap and postage basis?

 

Check your inbox

 

SC sent...

 

Thanks for the offer, but I'm on the opposite side of the world from you so I will try to source some from this continent, but if I have no luck I may just take you up on your offer

 

I'll trade you a 29mm opal for a 29mm shim

 

LOL!
That would be worth more than my whole bike!
Then again, a six pack of beer wouldn't be worth much less than it either!
;-)

 

What size are the Maxim-X shims? I'm sure my bike needs to be reshimmed as it's got 25k miles on it. I can't seem to find what diameter shims to look for tho!

 

Maxim X Shims are different… They are much smaller and are a little cap that goes on top of the valve stem, underneath the bucket

 

As Hogfiddles stated, shims are under the bucket, you have to pull the camshafts on the X to change .
If I were you and riding season is here, I would take the cam cover off and measure your clearances.
With any luck you may be good to go. If a few are tight I would button it back up and ride until you have a chance to tackle this.
Len is fast shipping but you're going to be down for a week at minimum.
You should always synchronize your carbs after a valve adjustment so prepare yourself for that also.

If you find any valves with zero clearance do not ride, proceed right to the shim swap.

 

Tight shins have been a major cause for “X” model demise. With such a small valve they can overheat quickly and cause engine total failure. There are more than a few that have been parted out because spare engines are hard to find.
There is one near me that otherwise is a 9.9 out of 10 but for a broken piston and rod explosion.

 

I saw mention somewhere of 7mm diameter shims. Does that sound right for the X, then? I'm definitely going to shim them. While I'm at it I may as well give the carbs a good cleaning at the same time!

 

The diameter of the shims is not the issue (not saying any shim will do......you gotta get the right ones). Getting the right kind of shims (which are for the MaximX/Fazer/Genesis engine, and doing w clearance check to calculate the needed thicknesses, then replacing/swapping shims to get the clearances back in range is the issue.

The general demise of the X was not due to shims, as much as it was due to people not understanding the power of the engine, and the speed of which it would accelerate, and not being able to handle it.. A lot of people wrecked them. The shims are much smaller, the buckets are much smaller, the shims are under the buckets, the engine is a water-cooled engine, and there are 5 valves per cylinder, and the interval for checking them is vastly different than the airheads which need to to be checked MUCH more often than the 'X.

 

Airhead XJ shim


MaximX shims

 

Hey all I’ve got a 93 seca 2 and I’m seeing posts saying shims are 29mm diameter but i just ordered some and they’re too wide. I measured the ones installed my bike and they seem to be 25mm. Does that sound wrong?

Stacked to show the size difference:

 

Check the following pics:
25mm

29mm


I have a good depth to the 25mm shim pool, too, so let me know what you need, and I’ll see what I have.
Dfox

 

Copy that thank you!