Will a loose chain cause motorcycle engine to surge?

I've ridden motorcycles for years, but my most recent bike is the
first with a chain drive. Its a 1992 Honda CB750 Nighthawk. I got it

Not a LOT of years, apparently. Not too long ago, ALL bikes were chain
drive.

About 2 mili-seconds after hitting the send key, I realized that somebody
would point out something like that. There are probably other examples too.
Almost all of the bikes commonly available in the U.S. were chain
drive...........screw it; never mind.

with about 25k miles on it. I've noticed over the past couple of
months a problem that is getting progressively worse. While cruising
along, at most any speed, the bike feels like its surging. I don't
know how else to explain it. The engine does not seem to be losing
power or cutting out. It does this surging mainly while maintaining a
speed, not so much when accelerating and not at all when decelerating.
I had considered the most likely cause to be dirty jets in the
carb(s). But may have found a potential other cause. While lubricating
the chain this week I noticed how much play there was in it. It was
enough free play to let the chain touch the bottom of the swingarm. I

Thanks for the feedback. You learn something everyday, and this is my
lesson for the day.

got out the Clymer's manual and adjusted the chain as recommended. I
discovered that adjusting it as far as I could, still left more free
play that there should be.
Could the sloppiness in the chain cause the surging in the motorcycle?

I have to disagree , TOG . In cases of uneven stretch or wear , it can cause
a surging sensation , and his looseness probably amplified it . I found
this to be true after my '76 FLH (RIP) locked the tranny due to a failed
shifter fork at 50+ mph . The section of chain that took the shock stretched
, and I had a helluva time figgering out why the bike didn't feel "right" at
speed . Replaced the chain and sprockets (that hurt , they were nearly new
!) Admittedly , this was an extreme case , it also put four cracks in the
tranny case around the main bearing . And bent the mainshaft ... and sheared
the clutch hub key .

It can. Start with that and go from there.

While moving, does the play in the chain relate to it jumping up and
down and affecting the movement of the bike? I have a new chain
ordered and I guess I will have my ultimate answer when I install it.
But it still makes me wonder if the problem is related to the chain or
is it a carb or air intake problem. The air cleaner is pretty clean.

Chains don't wear evenly, there will always be links that wear more
than others and cause tight and loose areas when you try to adjust the
chain. You might feel a resonant vibration from the tight/loose/tight/
loose chain as it went around the countershaft sprocket.

I replace hardened steel OEM countershaft sprockets every other chain,
and I clean and lube the chain with 90 weight gear oil religiously, as
I have found that tacky commercial chain lubes will glue the o-rings
to the side plates and the o-rings will split and fly out of the
chain. After that happens, the sealed-in factory grease get lost and
that link wears out quickly.

Surging problems can be related to dirty jets and internal passages in
your carbs.

I keep my carburetors clean by pouring 4 or 5 ounces of Berryman B12
Choke and Carburetor Cleaner into a full tank of gas. B12 comes in the
usual aerosol can or it can be bought in the liquid form, which is
handy for adding to the gas tank.

After several miles of riding, the carburetors are squeaky clean.

You can also run into surging problems if all the parts of your air
box aren't installed.

I once removed the rubber air intake snorkel from my GS1100, thinking
that the engine would breathe better if it could suck air through a
larger hole in the air box.

I was wrong, the engine surged violently at 6000 RPM. So I reinstalled
the venturi-shaped rubber snorkel and the surging quit.

The venturi shape of the snorkel wasn't as important as the length of
the snorkel, removing the snorkel changed the resonant frequency of
the air box.

I would be interested in hearing any thoughts on this. I will repost
after I install the new chain.

Are your sure it wasn't just a windy day? If not, I'd guess something in
the fuel/spark area. Whenever I felt my bike surge, I discovered not long
after that the trees were being blown around. I had a 1992 Nighthawk 750.
I enjoyed it quite a bit.

Seems you've gotten your answer on surging and the chain. If your
chain is worn out, worse things can happen. At my localrepair shop,
I've seen holes in engines from chains breaking. Get it repaired.

Do NOT replace the chain alone. You need to do both sprockets along with
it. Really.......or the new chain will be toast in no time flat.

And yes, a chain stretched that much can cause it to feel funny when
"coasting" under very light power.