Xj650 valve measurements

Here are my measurements on my 83 xj650 I am totally confused what I need to do to get the valves within specs. As you can see I can’t get a reading on three. Any help will be appreciated

History, bike sits for over 20 years it only has 1200 miles on it. Motor was froze up due to moisture freezing up cyl #3. Mechanic said valves couldn’t be ground due to a special coating on them. All valves were replaced.


Intake 1 pad # 295 less than .05 mm
Intake 2 pad # 290 less than .05
Intake 3 pad # 290 .05
Intake 4 pad # 295 .40

Ext 1 pad # 280 less than .05 mm
Ext 2 pad # 275 .15
Ext 3 pad # 280 .20
Ext 4 pad # 275 .10

 

I'd say 2-3 on intake should be changed for 280 giving .15mm #1 should be changed to 285 to give .15mm.

#4 is an oddity, you'd have to change to 270 to give .15mm.

Exhaust:
#1 change to 265 to give .20mm
#2 change to 270 to give .20mm
#3 LEAVE AS IS
#4 change to 265 to give .20mm

Hope i remembered my clearances right lol if i'm wrong, someone will chime in.

 

Put your 275 shim in to I1, I2, and E1, then read them. That should give you enough clearance to get a reading. We hope.

Your E clearance should be .20mm, and your I clearance should be .15mm.

USE THIS FORMULA (warning, math ahead):

Current Pad Size (in MM) + Current Clearance - Desired Clearance = Proper Shim Size


So for, say, E4, 2.75 + .10 - .2 = 2.65, or size 265 shim.


And for I4 2.95 + .4 - .15 = 320...not 270.

I would use an excel spreadsheet, but that's just me. In fact I will add it to my current Motorcycle sheet right now.

 

HAHAH ya i went the wrong way there on the I4 thanx day

 

So int 4 should be a 320 pad?

 

Yeah. I didn't catch it either until I tried to use that one as an example! That would have been a huge gap! Thing might have jumped clean out of the bucket. Bad bad bad.

So grmeyers, yes, do your own math. Double check your clearances, and if it's all the same, I4 should be 320.

 

315 (295 +40 -20 = 315). Double check your measurement - seems awfully thick.

 

Intakes should be .15 MAX correct, not .20 (that's exhaust)

 

But ya, if you actually are measuring .40, maybe you've got a bent valve that's not closing all the way. SOMETHING has to be keeping it open to have that kinda clearance.

 

It does seem very strange, but if you look at the chart .40mm isn't all that far down the list. 320 is the biggest size though.

It should be double checked, especially since all the others were very tight and it is a non running engine, but .40 isn't excessive.

 

Your answer is right here. Were the magical ungrindable valves lapped at least, do you know they were all closing properly before you reassembled the head? It's also possible that one valve is wrong, that it's from a different motor but "close" so it was used.

Do you have the old valves that came out? If you end up pulling it back apart you can compare...

 

Yes I do still have the valves. I will take them back to the mechanic and have him to compare. I am assuming that the valve seat can be replaced if it was lapped to much?

 

I shouldn't have skipped my nap yesterday. Thanks for the save.

If he took too much off the clearance would be tight, not loose.

 

That sounds better, just maybe if need be he can take more off the seat to get to a closer tolerance.

 

Thank you and the rest that give me the info, I was able to get within range on int and ext. Was able to find the disc for $3 exchange and the Yamaha dealer exchanged the 320 for free.

 

Do you buy these shims in a kit somewhere or do you buy the shims after you measure? where do you get them?

 

There are kits.

I bought mine individually after I measured as I only needed 3. Some people change locations of them (I did). Some people buy replacements for all the out of spec valves.

You can get them from your dealer, online, or our local parts guy Len. Chacal is his forum name his ad is in the upper right corner xj4ever.

 

Check with your local stealership. The same place that charged me $10 for an oil filter exchanges valve shims for free.

 

chacal carries aftermarket shims for about half of what Yamaha gets.