Valve clearance

[Alf]

This year I start with anticipation: the pull throttle cable is broken, so I´m working in a complete service that I was thinking to start next September.
- Oil & filter
- Front end bearings re-grease and checked
- Rear end new swing-arm and dog-bones bearings
- New chain and sprockets (I will post a front sprocket pic after 90.000 kms. It is clear than the OE es the best)
- Paint and polish various things
- etc...

When doing today the valve clearance service, I´ve observed than the clearances are open, near all of the exhaust into de 20-25 mm gap and half intakes into 15-20 mm. I´m very surprised because the valve clearance gap usually decrease, not increase with the use.

Any explanation?

[FJmonkey]

When doing today the valve clearance service, I´ve observed than the clearances are open, near all of the exhaust into de 20-25 mm gap and half intakes into 15-20 mm. I´m very surprised because the valve clearance gap usually decrease, not increase with the use.

Any explanation?

Climate change.... Sun spots..... exchange rate change on the Yen....

[Arnie]

When doing today the valve clearance service, I´ve observed than the clearances are open, near all of the exhaust into de 20-25 mm gap and half intakes into 15-20 mm. I´m very surprised because the valve clearance gap usually decrease, not increase with the use.

Any explanation?

Maybe your through studs have stretched, or the head nuts have loosened, or there has been wear between the lobe and the lifter instead of recession on the valve seats, or you were drunk when you last adjusted the valves.
Doesn't really matter - reset the lash correctly and check again in 15-20K kms.

Arnie

[andyb]

20-25 mm gap and half intakes into 15-20 mm

That's quite the gap.  You mean a leading "." in front of those, I hope

If they're all doing the same thing, just measure again, set it, and if it fails to run well, look into it.  Otherwise, sounds like a measuring problem more than anything.

[yamaha fj rider]

20-25 mm gap and half intakes into 15-20 mm

That's quite the gap.  You mean a leading "." in front of those, I hope

If they're all doing the same thing, just measure again, set it, and if it fails to run well, look into it.  Otherwise, sounds like a measuring problem more than anything.

+1 Andy gives great advise.

Kurt

[Alf]

No, it was not a measure problem. I was with my friend Mingo too, a competent restorer, mechanic and FJ owner. I even change my feeler gauge set because I was surprised: I´ve ridden more than 400.000 kms in my 4 FJs along my life with their correspondent 12-24.000 kms valve maintenance doing it myself, I performance this task habitually in 6 FJs of my friends and I´ve never seen that the valve clearance gaps increase in 6 exhaust and in 4 intake ones in 24.000 kms, hence my surprise

We inspected the cam lobes, the valve shims... no wear at all. The studs and the head nuts don´t affect clearance

Maybe Arnie could be correct and we were drunk... 

I´m going to make a compression test. Could it be due to carbon deposits in the valve? And the bike don´t sound like a can full of nails due to excessive valve gaps

[JMR]

25mm is approximately 1 inch. When I ran the stock FJ shim/bucket arrangement the gaps always opened up. Most of the time (meaning other bikes) the clearances decrease.

[Alf]

And what do you do?. Like the difference is not too much (the worst exhaust valve is at 0.23 and the worst intake 0.18) I´m thinking leaving them alone and checking again in 12.000 kms, not 24.000

What do you think?

[JMR]

And what do you do?. Like the difference is not too much (the worst exhaust valve is at 0.23 and the worst intake 0.18) I´m thinking leaving them alone and checking again in 12.000 kms, not 24.000

What do you think?

That's OK.

[yamaha fj rider]

A little loose is ok.

Kurt

[Alf]

Gracias, amigos.