1993 VFR Knock

Hello everyone...I tried to do a little research as to what could be causing a pronounced knock right around idle on my VFR. Came up with 'cam end float'...and because humans are a naturally hopeful breed...I am hopeful this is my problem.
I've had this bike for a few months now...and it has 31k on it. By all accounts it has been well maintained and adult ridden throughout it's life. It shows as gorgeous and was thought to be mechanically sound. The knock is pronounced at idle (but only sometimes!) and disappears entirely when the engine is revved above idle.
My mechanical skills hover somewhere around changing the shocks on my pickup. Maybe a little more advanced ... but not much. Can anyone give me any insight as to what to expect (noise-wise and throughout the rev band) if this is a serious mechanical problem? I don't know the guys at my local Honda shop well, and would like to keep it that way. They seem to specialize in Trail 90s, outboards, and chainsaws.
Any thoughts or input would be great.
Thanks!

 

Timbersnake,

 

Timbersnake,
I have a 91 with 29K. I have also experienced a wierd knock at idle from the day I bought the bike (3 years ago at 18K). It sounds like "cam float" to me. It's not a true consistent knock. It's a different sounding knock compared to a valve tap or rod knock. The noise comes and goes but always at idle and it seems to be coming from the rear head. When slowly increase the rpm's from idle, it disappears around 2200 rpm's. I checked all the specs on the cams when I did my last valve adjustment and everything was at the top end of the specs. The one thing that made a difference was oil viscosity! when I run 20W50 I get this noise. However, when I run 10W40 it completely goes away. The only thing I can guess is that the thicker oil does not get pumped as well to the cams at idle.
I would suggest checking your cam specs at your next valve adjust. I wouldn't worry to much if it's not a true knock, it comes and goes, and it's not getting worse.

 

Good idea!

I read some of the stuff on cam float...and it makes sense that lowering the viscosity of the oil would have a similar effect to drilling to increase flow. Can we go too low? 5W-30? Next time I have the machine in for valve day I'll ask the mechanic about drilling. (I found the schematic on here somewhere...looks straight-forward) Thanks for your help.

 

i've heard 5w30 can fling off too easily...

 

Cam float sounds about right. My '94 does the same thing; not all the time but it is noticeable when it does. One of the European VFR sites had information on this subject, I'll have to see if I can find the one. From what I've read, it's an oil-delivery problem that is easily fixed by drilling a hole in some part in the head. Since the problem doesn't appear to hurt the engine any (their words, not mine) I didn't worry about it too much. The problem was fixed on newer VFRs.

 

honda tech sheet oil way mod

here is the honda tech sheet showing where to drill the 1 mm oil ways

Pictures by imaginationman2003 - Photobucket

 

Anyone know when this was fixed? Curious whether my '96 would have the new oilways.

 

This was a 3rd gen/early 4th gen problem, fixed in newer versions. When i say early 4th gen, i mean first few months of 94 (mine was manufactured 1/94)

I'm gonna have fun drilling those 1mm holes; thank god i have a drill press...