High Milage Valve Check?

[jaydj]

At nearly 70k, my 2000 is running a little rough. No mis-fires or anything, just kind of rough, like it vibrates a bit more. I am going to replace the plugs with NGK Iridiums, but I am wondering if a valve check is in order. I have read a few of other threads which all seem to lean towards "not" doing the valve check as VFRs (and Honda's in general) maintain their spec well/don't really go out of spec. This was from some supposed Honda mechanics as well.

Kind of an expensive service, so curious as to other owners experiences here. I've not done the plugs since I've got the bike 50k ago, and I do change the Mobil 1 synthetic every 5K. Any thoughts as my VFR approaches middle age would be appreciated.

[TNRabbit]

At some point, it needs to be done. Since you're experiencing some issues, could be an ideal time.

[stoneman]

Could be numerous reasons but i doubt its the valves(when were they last done?) causing the vibes..check wheel bearings,chain and sprockets,suspension bearings/linkages etc

[Terry]

I checked my VFR at 76000km, as I had no idea of when/if the PO had done them. Result was that four of the intakes were tighter than spec, but all the rest were spot-on. With use/wear you'd expect the clearances to close up, eventually you'll run out of clearance and burn a valve or two, so if you're planning on keeping your bike for the long haul, this is good preventative maintenance.

It's pretty easy to get into the back head and measure the clearances. If these are OK then you could reasonably expect the front clearance to be OK as well.

In my experience, the VFR is a pretty easy machine to replace valve shims on, as it has no cam chain to deal with. If you've got patience, some basic tools (and I'd insist on a torque wrench here) this is definitely in the DIY category. I bought a set of Hotcams 7.48mm shims for about $80 on Amazon.

However I'm not going to suggest that the valve clearances would account for rough running unless you had burnt a valve, and I suspect there'd be other symptoms then as well. Changing the plugs is a cheap and sensible exercise, another aspect which could give some rough running would be the starter valve synchronisation, after that you're into something like an air leak in one of the rubber boots between the throttle body and engine, or even a crack/leak in one of the many vacuum hoses.

[auggius]

I did my valves on my 4th gen last year at 167K km. I think I had 5 or 6 tight valves in total. I can't say that I really noticed a difference afterwards but on my first long ride this past weekend I got 50mpg (that's imperial gallons up here in Canada), up from my usual 42mpg. And that's with a possible exhaust leak somewhere. My once quiet, stealthy bike has a rumble to it like an aftermarket pipe.

But it was satisfying to do the work myself. 5th gen will be similar in terms of degree of difficulty. Gear driven cams and no VTEC valves. I used a tip about removing cams that was really helpful. To remove a cam find a spot where none of the lobes are pressing on a valve. Mark the cam position relative to its adjacent cam using Sharpie. Now you can remove the cam and put it back in place with your alignment marks. It does mean that you can only do one cam at a time but for me that was okay.

I haven't done a carb sync on my bike either. What's the equivalent on a fork injected bike? Might be something to consider.

[Mohawk]

Out of sync starter valves cause rough running on 5th gens, so sync them according to the manual, it is quite amazing how the engine smoothies out & revs freer as the starters come to the sync point.