4 stroke Kawasakis of that era had roller cranks. I never had any 4
strokes of other mfrs apart in that time frame, but my 2 stroke Kawis
and Yamahas certainly had rollers. My plain-bearing Kawasaki and Suzuki
4 strokes of the early & mid 80s were equally bulletproof even when run
a number of seasons of endurance racing, never had a lubrication system
issue though they were run far harder than any street bikes. The problem
with rollers was that they could tighten up when they got hot and power
was lost overcoming the internal friction. The engines could be built to
tighter tolerances and would produce more consistent power over longer
periods of time with pressure-fed plain bearings. That's why the bike
mfrs changed to high(er) pressure oil pumps and plain bearings. This was
before the switch to liquid cooling. I believe the same principles, for
the same reasons, were applied years earlier by Continental, Lycoming,
and Franklin in the design of their aircooled engines for light aircraft.
On 8/12/2020 4:12 PM, Mike Stirewalt via KRnet wrote:
This isn't relevant to anything but I'll test the group's patience anyway
. . .
Over the last 25 years I've had two Suzuki GS-850G motorcycles. The
first one, a '79, eventually blew a head gasket at 75+ thousand miles and
I've kept it for a parts bike. The second one, an '82, is my daily
driver. Born in the heyday of the 750's (Honda's, Kawasaki's, Suzuki's,
etc.), that is in the mid-70's and on into the 80's, these four-in-line
engines took the motorcycle world by storm and of them all, Suzuki's
design has proven to be the most resiliant . . . the most "bulletproof"
- a conclusion arrived at by those bike journalist/historians who
periodically write articles on this subject. One reason (I've repeatedly
read) for the Suzuki's durability is due to their use of rollar bearings
on the crankshaft. I don't know enough about what the other companies
used back when these Suzuki engines were new, but I'm assuming they used
plain bearings. Could be wrong. What I can say for sure is these
Suzuki's of that era have proven (in my limited experience) to be the
most reliable machines ever built. A conscientious owner would of course
pay attention to oil and filter changes, valve adjustments, transmission
and final drive fluid replacement, etc. but the amazing thing about these
Suzuki's of that era (and perhaps since, I've no idea) seem to soldier on
whether any attention is given to maintenance or not. They seem to be,
if not the most foolproof mechanical devices ever invented, certainly up
near the top of the list. Using roller bearings to sustain the
crankshaft in these bikes seems to have been perhaps the most critical
design factor in their longevity. Bike fundis much more experienced
than I have made this observation over the years so, based on my many
years of hands-on experience with these utterly reliable bikes, I can't
but agree. The fact that knowledgable people found it relevant to make
this distinction re the Suzuki crankshafts, makes me think the other bike
makers _didn't_ use roller bearings.
If Harleys use roller bearings on their cranks, I finally have something
good to say about Harleys!
Mike
KSEE
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