VF500F now running great but I have worries and need advice.

Well the very good news is that, with a lot of help from the forum, my $400 '86 VF500 F econo project bike is running like a top. The grand total in it so far is $650 and that includes a $65 E Bay chin fairing that I got for when I get around to the "beautification" phase.
It is every bit as nice to ride as I remembered from when I last rode one in 1990; very torquey, super smooth, light and just plain fun to ride. It idles smoothly at 1000 RPM, doesn't smoke and I would be ecstatic, but it has a knock which seems to come from the lower right side of the engine. It is RPM related and isn't audible riding with a helmet on, but it is there and doesn't sound at all like a tappet click when listening to it off the bike. I have tried the metal rod to the ear listening technique but can't localize it well.
I really hope there is some benign cause or at least affordable fix, I'm back in love with these little gems and don't want to give up on this one. The bike only has 15K miles and bottom end problems are reputedly rare so I'm hopeful although worried. When I was setting the valves I noted that the engine internals were spotlessly clean and the cams and rockers perfect.
Thoughts and suggestions will be greatly appreciated, the only reason I've gotten this far is because of forum members input, so thanks in advance.

 

I will agree, bearing issues are rare on these engines. Have you done a carb synch? If the carbs are well out of sych in can cause engine noise. Including in the clutch pack. Does it sound like it's coming from behind the clutch cover? Or deeper in the engine?

 

It does seem to be coming from behind the clutch cover, but it is hard to be sure. I carefully bench synced the carbs using the strip of paper in the butterflys method and the engine and idle are very smooth so I think they are close. I would love it if the noise was from the clutch pack but am not clear as to how that would cause a knocking sound.
Regarding synching the carbs on the running engine, I have a good mercury carb synch unit but lack the Honda tool that seems to be necessary to do the physical adjustment, so I'm kind of up the creek on doing that.
Thanks!

 

There is a simple check for big end wear. Get a dial gauge & put a slip fitting rod down each spark plug hole. Then turn engine by hand through TDC then when it gets to BDC stop & press down on the rod, if the big end is worn the rod will move & the gauge will tell you how much.

I had this noise on my ZZR250 turns out they all had a dodge plastic clutch buffer. If you watch any You Tubevid of the 250, they all sound terminal at idle ! So it could be a clutch issue. If the bike has that little mileage, I'd strip the clutch & clean all the plates ! Might fix it.

 

You'd be surprised how far off bench sych's can be. I'm putting my money on a carb sych. I have a special screwdriver designed just for carb syching. It's a telescoping screwdriver bent at a 45 degree angle at the end.

IMO the 500f's are the hardest to sych. It will make life much easier if you had someone to hold the throttle open for you while you make synch screw adjustments. Holding the throttle open in different positions makes access to the synch screws much much easier. KEEP in mind that you must shut the engine off before making adjustment on the synch screws. Restart engine, blip throttle a couple times and check your readings. A bright source of light is a must have also.
I purchased a non running 86 a few years ago. Did the bench synch thing but the engine noise was certainly concerning. At the time I didn't have the tools to synch carbs so a freind of mine did it while I held the throttle open for him. I was AMAZED of how much quieter the engine was when finished.
So, do a carb synch first then we'll see where you at with the engine noise.
Jeff
(image stolen from a thread on the VFR Club forum)

 

Thanks for the hopeful possibilities and useful advice guys. I will synch the carbs as soon as I get a new gauge since it turns out my trusty 20 year old Motion Pros mercury resiovoir had cracked and leaked its mercury into the box I keep the gauge stored in. I will report back as soon as I get the carbs dialed in. Keep your fingers crossed for "no knock" at that point.
The grand total cost took a big jump today since the title transfer and license plate came to $193.90 !! Maybe with creative accounting I should omit this as a bike expenditure and classify it under Legal or Entertainment...