FJ build FINALLY coming to an end........

[FJWizard]

I posted 18 months ago about an FJ1200 I bought with 3800 original and documented miles.  Bike is showroom new.  http://www.fjowners.com/index.php?topic=12572.msg124960#msg124960

The bike had been under a tarp in a heated garage and not started since 1995. I put a bunch of work and $$$ into it fall of 2014, got it 99% done, but, now it has sat in a corner of my shop for over a year....I have too many motorized toys. It is time to finish the old girl and ride her this summer.

The only remaining issue was a loud ticking/tapping from the cams.....to the point I didn't want to ride it until a root cause was discovered.  I have a lot of wrench time on FJ motors from years ago......I know they sound like farm implements, but, this ticking was not typical.  So a few days ago I pulled the cam cover and checked the valve clearances again.  I discovered something interesting. 

Checking the clearance using the factory service manual procedure yielded nothing out of spec. I was thinking maybe a valve guide was bad, so I called the local Yamaha shop and checked with the service manager.  He is an old salt and told me he's wrenched on plenty of FJ's over the years. He suggested that I check the valve clearance across the entire base circle of the cam......not just at the factory positions outlined in the manual. I spoke with Randy about this today and he said the same thing.

Eureka!!!  Several of the exhaust valves that measured .0065 at the recommended positions were actually .010 when the cam lobe faced straight away from the bucket!!! A few of the intakes that measured .004 are actually .0075.  I swapped out 6 shims in the fall of 2014 when I checked the valves then......so I likely contributed to the excess clearances and subsequent loud clacking. I mic'd the cam lobes and all are in spec.  Randy said he checks clearance the same way.  Start with the cam lobe positioned right after the valve is fully closed, and while turning the crank bolt counter-clockwise, rotate the cam lobe slightly, stop, and probe with a feeler gauge for go or no-go...find the maximum size that will fit at any point around the cam base circle....in many cases the maximum clearance is obtained nowhere near the cam position recommended in the factory, Haynes, or other manuals.

Aside from the loose shims, I decided to change valve seals and install KPMI springs, + a fresh coat of paint, so I pulled the head.....and since the paint on the head and cylinder has to match, I pulled the cylinder, and since the cylinder is off, I ordered a Wiseco 1219 kit. With 3800 miles, the factory cylinder bores and pistons look new, so I saved them aside and bought a used cylinder block off ebay to bore 1mm over. You guys know the drill......it goes on....and on......and on......and on. LOL 

Anyway.....couple of questions:  Are the KPMI springs ok to use with the factory retainers/locks? Also, I am mulling installing hotter cams......nothing wild, just a step up from stock since I am not porting the head and keeping the factory Mikuni 36mm CV carbs. I do not want to significantly diminish the stonking mid-range of this engine.

[4everFJ]

Good that you found the problem.

However, I don't get it? Why would the clearance be bigger at the cam base rather than at the normal measurement position?

With only 3800 miles on the clock, surely it can be uneven wear.

If there is clerance, no matter what the clearance is, the vavle is fully closed. It doesn't open/close more at other cam positions.

Only explanation would be that the cam lobe profiles are different at the base. But, I am sure that Yamaha didn't provide a wrong measurement position in all their factory service manuals... I would stick to the measurement position specified by Yamaha, but that is just me