Mike is right - I use Hitachi SUs with horns and rev my R16 to 7500 RPM. I
run the carbs pretty lean (gotta be careful) and don't have a problem. I
DID have lots of problems with valve float with stock springs and an ISKY
.420" lift cam - it would break up and sound like a broken valve spring from
about 6200 to 7000 RPM, than take of like a rocket (some kind of weird
harmonic, I suppose). I cured the problem with NISMO 99996-H1133 valve
springs for the A12/A13 engine - 130 lbs. seat pressure @ 1.610" installed
height. It'll rev over 8K, if I had the $$$ to replace bearings every
couple of races!.
NISMO also has a 99996-B1061 "progressive" valve spring for the R16 - 90
lbs. seat pressure; Coil bind .400"
JH Bahn
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