Motorcycle Repair: Honda Super Cub hesitation, uneven under load., honda super cub, model honda

Question
Hi.

I have a 2004 model Honda Super Cub (49c, 3 speed) 9000kms
approx. on the odometer.

The other day, I noticed a surging or hesitation when riding
under load, up a hill, or on acceleration in 2nd or 3rd gear.

The bike starts fine as usual, and I can't hear any unevenness in
idle or throttling it in neutral. Only when in gear and under load
is it noticable.

Also, under high speed conditions (for a Cub :), at 50-60kph on
a straightaway, little to no wind, the bike surges every few
seconds or so, as if a hand is holding back the bike or as if gusts
of wind are slowing it a split second  or so, moment to moment.
But it's the bike, not the terrain or weather factors. At that
higher speed, I can't hear the engine running well to listen for
unevenness. The bike doesn't seem to have a lack of power
generally, except for the unevenness.

Related, or unrelated to this, I failed to start the bike a day or so
before this happened. It almost started, but I guess I didn't give
it enough kick or choke properly. So it sputtered for a second
and died. I tried to restart it, but noticed that the kick start
wasn't feeling resistance as it should, as if the spark plug was
removed. This worried me. So, I waited a few moments, tried
again, and the same. Each time I tried to kick start, the lever
didn't have enough resistance behind it, so my kicks just went
down fast. This happened once before when it stalled in a
downshift at a traffic light. I put it in gear and pushed it a few
feet. Put back in neutral and tried again to kick start. It worked.
This time I put it in 1st, pushed it a few feet, and it started up
while i was pushing it. I got on, put in back in neutral and all
was fine.  

I'm not sure if this experience and the above question problem
are related, but I thought I should mention it, as they might be.

Sorry for the longwindedness.

bobby r. (tokyo)
humbleradio@yahoo.com

Answer
Hi Bobby,

I suspect a fuel supply or fuel ventilation problem.

I would need to perform usual checks to accurately diagnose the problems.

Unlike the usual, dependable one-kick engine start, Cubs tend to need a few extra kicks to get them started if not used for several days.

Check the fuel system for obstructed or pinched hoses, check fuel filter, check carb for evidence of varnishing, clean or replace spark plug, check fuel tank/gas cap vent, check fuel tank for evidence of rust, and check the air filter or air intake for restrictions.

Respectfully,
Mark Shively