First Winter project - Valve Adjustment.

The first thing I wanted to do this winter was to get my valve clearances in order.

So I went out to the garage and tore the valve cover off my XJ650 and checked the valve clearances. That valve cover was really happy where it was for the last 30 years and it took quite a bit of persuasion to get it loose. Since this bike is pre-YICS, the valve cover didn't have the cross piece shown in Bigfitz's most excellent write up on this topic. I ended up using a hammer and a piece of PVC for a drift and CAREFULLY tapped on the fin in each corner. It finally broke loose (the valve cover not the fin).

Much as I expected from reading on this forum, all my valves are tighter than spec.

Clearances in (mm) converted from inch measurement (no metric feeler gauges yet)

Intake .076 .076 .102 .051
Exhaust .102 .127 .152 .102

Since the acceptable clearance range is 0.04mm and the shims are available in 0.05 increments, it's apparent that sometimes you can't fall precisely in that range. For example my best valve is 3 exhaust and it is slightly tight at .152 (minimum is .16). If I swap in the next thinner shim, it will then be .202, which is a little too loose.

Based on the experts here, I assume I should err on the loose end in a case such as this.

Does this sound correct?

I used the 12 ga. solid wire through the spark plug hole method to check all the shims. It worked well except the 2 center intake valves were a PIA. It seemed as though there is a little less room to get the shim out and the wire maybe needed to be a little thicker to keep the valve and bucket lower.

Next up - new shims, compression check and some new SS brake lines.

 

The wise ones have spoken - - go large, let it wear in.

I do the 12/2 wire trick also.

If no one touched your valves, ever, then no one looked at your rear brakes. . .

 

Especially since you're "converting" from Imperial to metric without "rounding."

I totally agree; I'd re-shim exhaust #3 along with the rest of them.

It's at .15mm, minimum is .16mm. That .002mm doesn't really matter, especially if you convert back and realize that .002mm=.00008". Not driving yourself crazy trying to be too precise is another good reason to pick up a metric feeler set.

One last note: Don't think of valve adjustment as a "project" if you plan to ride the bike much. You'll need to do it again in 5000 miles; it's just a part of "required maintenance" like oil changes, and carb sync.

 

TIMEtoRIDE - Thanks for the suggestion. I checked the rear brakes and replaced the front ones before I took the bike out on the road in September.
BigFitz - Thanks for confirming my plans. I was going to adjust that valve along with the rest of them.

Thanks guys.