From: ramarren@apple.com (Godfrey DiGiorgi)
Newsgroups: rec.motorcycles
Subject: Re: tune-up (and Fiamms)
Date: 25 Aug 92 20:55:10 GMT
Followup-To: rec.motorcycles
Organization: Apple Computer

In article <1992Aug25.151400.8551@sifon.cc.mcgill.ca>,
loki@nazgul.physics.mcgill.ca (Loki Jorgenson) wrote:

> 	1) My plugs were a whitish-yellow instead of the usual tan; I can't
> 	  remember what that is supposed to mean.  Mixture is too lean?
> 	  What do I do?

If they are stock plugs, stock jetting on an FJ, and they don't look
blistered or otherwise heat stressed, leave them alone. The old golden
tan pictures were from days of leaded gasoline.

> 	2) The plug gap was on the narrow side of specs.  I widened them
> 	  to sit in the middle of the range.  This should advance my
> 	  timing a bit and heat up the spark.  It also seems to have
> 	  improved my power a bit.  Any comments?

Changing the plug gap does not change the timing or heat range of the 
plug. It simply lengthens the arc pushed by the coils or igniters, 
increasing the time of the spark. This is good in that it's 
making it more likely that all the mixture will be ignited; it can be bad
if
your wires are getting a little old as they'll be more prone to leak a
little
spark.

> 	3) As was advised in a posting long ago, I started out measuring
> 	  the valve gap at about 5 different places around the back of the
> 	  cam lobe.  I got tired of this pretty quick and realized that I
> 	  could reduce the hassle by just selecting the two feeler gauges
> 	  on either end of the spec range, poking the thinner one in at
> 	  each of the five (or so) points until it passed through and
> 	  then poking the thicker one in.  If the thin one didn't pass
> 	  through at any point or the thick one did, then I went back
> 	  and did a full set of measurements.  Does that sound
> 	  alright?

I dunno the FJ setup, but I know that in the shop manual for my bikes,
it says something like "set the cylinder to TDC compression stroke". I've 
always done this and not worried about the point by point measurement,
within reasonable limits. (Certainly, I look at a closing rocker on a 
Ducati Desmo and make sure that it never goes to a negative tolerance
all the way around the cam profile ... :) 

I usually do the same thing you do: poke the thin end of the range
into the clearance to make sure I have minimum clearance, then poke the
thick end+1 in to be sure I don't have too much. Should be an adequate 
check if the tolerances are specified correctly.

> 	4) I have the dreaded Yamaha valve gasket leak, both from before and
> 	  after my sojourn.  What can I use (besides a new gasket and bolt
> 	  washers) to seal it against leaks?  I have heard about using 
> 	  silicon rubber but I'd like to hear it from a Denizen that I 
> 	  trust (know any?).

If you have a leak, then new gasket and bolt washers are in order. I use
Yamabond as a gasket sealant, and have used it successfully on all the 
bikes that needed gasket sealant since about 1974 (Nortons, Triumph, 
Ducatis, Hondas.... you name it). I recommend it highly.

> 	5) Several of the valve clearances were just below or just above
> 	  the spec limits.  Since the range is only 0.04mm and shims come
> 	  in 0.05mm steps, is there any point worrying about these ones?
> 	  Is it better to be slightly over-loose or slightly over-tight?

In the vast majority of cases, valve adjustments tend to tighten with 
age due to wear, valve stretch, and seat pounding. Maintaining minimum 
clearance is much more important than having a little to much (within
reason). It's not as precise a setting as the abundance of specs seems
to imply, but you should always have minimum values or risk other cylinder
head trouble.
========
Godfrey DiGiorgi | ramarren@apple.com | DoD #0493
"Logic may be the beginning of wisdom, but logic never bought
 me a Ducati."
 Rule #1: Never sell a Ducati.
 Rule #2: Always obey Rule #1.
Honda VFR700 Intercepter 1987, "Bright White"
Ducati 750GT             1975, "Thunder"
Ducati 250 Mk III Diana  1966, sleeping beauty
Toyota MR2               1985, "VSSC"
========
Newsgroups: rec.motorcycles