I'm only making a suggestion. You have the bike taken apart already. Checking the clearance on the valves doesn't require you to replace anything or take anything else apart. You only need a feeler gauge. If you find any valve clearances that are significantly out of specification, then it's up to you to decide if you want to do anything about it. But at least you know.

As for what most riders do with regards to maintaining their bikes? Well, you don't strike me as "most riders". Would most riders have done what you've done with this bike already? If as you say most riders don't do anything with regards to maintenance, then there is no telling what else may be wrong with the engine. If you have a copy of the F4 shop manual, you can see that it's a relatively easy procedure to "check" the clearances. What you do after is up to you.

 

You're right, I'll check the clearances, actually kinda curious how they held up from 1999 until now. Yeah, sad truth is that most riders, at least in my neck of the woods, are obnoxious POS, buying really powerful bikes swapping the exhaust and riding full throttle in first gear through the streets at night. Anyway, any other thought on what i should check? I'm really concerned about something lower in the engine, but don't want to take off the oil pan. Also i'm having trouble finding a new water pump, i can on find used ones.

 

I too am curious as to how they've held up. Keep us posted.

 

0.15mm give or take across the board. This is weird i would have expected the clearances to increase over time.

 

It depends on how the wear occurs. If the valve seat wears, then the valve sits further into the opening. This would raise it up closer to the camshaft lobe reducing the clearance. If the cam lobes wore, or the cups on top of the valve stems, then the clearance would increase. But if you're wearing lobes and/or cups I think you'd have bigger issues.

 

yeah, it's the valve seats and valve faces. now it explains why the engine was running hot, i first thought it was a mixture issue, but the exhaust valves weren't opening wide enough and the hot gasses weren't expanding enough. Will take the engine to a mechanic friend/mentor to see if we can repair the valves and valve seats.

 

Well, actually if the clearance is tighter, then the valves are going to open more, not less.

 

The camshaft is fixed and there is no visible wear on the lobes. But if the valve seat is worn and the entire valve rises the cam lobes striking the valve will still move it the same distance as before, but the valve is higher so from a hypothetical 3mm travel you subtract the lost clearance, in the case of exhaust valve, 0.28mm clearance, so the valve will open 2.87mm. Or is my logic flawed?

 

The height of the cam lobe is fixed, lets say 3mm. The clearance is the amount of space that the 3mm lift has to close up before even starting to lift the valve. If you reduce that gap, then the valve starts opening sooner and overall opens more. Make sense?