1987 Honda CBR600 (tuning?)

1987 Honda CBR600 ("Hurricane"), 20k mi.

Bike has been running reasonably well (tiny, tiny lo-speed miss) up until
the ugly, Ugly Aug. heat wave, during which I didn't ride.

Tried to start it about a week ago, it spluttered, idled on choke,
died when I tried to rev it up. I could choke it up to maybe 3k
rpm but it wouldn't take throttle at any choke setting. Goes
"clunk-clunk" and dies when throttled.

It has fouled plugs maybe twice in the 18 years I've had it. This morn
I fire it up for 2 min., then check to see which pipes are hot.
The only cold pipe was on cyl. 3.

So I get down on the ground and torture my hands to replace plugs.
The cyl. #1 plug was totally fouled, all black. The #2 was oily, I
think it wasn't properly torqued (near impossible to properly torque
in given space). #3 and #4 looked reasonably clean. Not what I
expected.

With 4 clean plugs, I fired it up and it did the same. Idled on
choke but wouldn't throttle at all.

I'm not sure where to start looking.

Anybody got a feel for such circumstances?

Thanks,
Puddin'


"Mit der Dummheit kaempfen Goetter selbst vergebens!"
-Friedrich Schiller

Puddin' Man wrote:

>With 4 clean plugs, I fired it up and it did the same. Idled on
>choke but wouldn't throttle at all.

Your idle jets and idle ports and passages are all gummed up.

As soon as you open the throttle, vacuum drops off and the "choke" stops
working and the engine stalls.

Cleaning of constant vacuum carburetors has been discussed numerous times in
this forum, so google up as many messages as you want to read about "idle
jet", "diaphragm", "transition ports", "EPA anti-tamper plugs", etc.

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