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On top the wrist pin, on the
bottom the exhaust rocker shaft. Both showing signs of stress and overheating. The bluish
area on the rocker shaft also shows substantial wear. I suspect the wrist pin overheating
was a by product of the piston scoring or vise versa. Wrist pin doesn't show substantial
wear, just some discoloration. The exhaust rocker shaft is also an oil passage, it seems
to me that a person could drill a small oil hole in this shaft at the mid point where the
rocker pivots to provide some extra lubrication for the rocker. |
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Scoring on the top side piston
skirt. This is the side of the piston that gets stressed on the power stroke. Piston to
cylinder clearance was a little loose when the motor was assembled but still in the upper
range allowed by the assembly manual. I was a little upset with my machine shop when I
first checked the parts before assembly but I didn't think it would cause a problem,
that's what I get for thinking. |
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One of the shift problem
culprits. This is the shift drum plate. The numbers 1 - 4 indicate the detent locations
for the various gears. N is of course the neutral detent. I have labeled two other areas
with a "p" these flattened plateaus between gear detents seem to cause a
problem, the detent roller will often part itself on top of one of these causing a false
neutral between gears, the p area between gears 3 and 4 is especially bad. Notice how
shallow the 2nd gear detent is, this was causing a real problem on the track, the gear box
wanted to jump from first to the p area between 2nd and 3 thrd gear instead of going into
2nd. The problem was made worse by the ill conceived shift lever that I built, it was too
long and heavy and felt vague when shifting. For 99 I will build a new linkage returning
the shift pattern to standard, I will modify the detent spring to engage the shift plate
harder and will probably modify the shift plate with deeper detent notches and try to
slope the plateau areas more. |