Motorcycle Repair: Starting problems -, carbon brushes, plain bearing

Question
1983 750cc Yamaha Midnight Maxim - Low Miles - I love
it... when it runs.

Starting problems -
It always takes FOREVER to just start. It turns over but
rarely "catches" - then when it does, (if I don't drain battery
from starting) it idles very poorly until I ride it for a while.
I have to leave choke open quite a while in order for it to
stop lunging forward like a bronco while I accelerate. It
looks like I don't know how the heck to shift, but the reality
is the gas just doesn't seem to be getting in there
smoothly.  The plugs all look good - maybe a tiny dusting
of greyish carbon, but pretty good. I've spent $$$ on 3 new
batteries and a 2 battery chargers in over six months. After
bike warms up, it'll start quickly, but then after it sits a
week, I go back to draining the darn battery trying to start
it again.

I live in Chicago, have no technical expertise with bikes,
and have no idea where to get work done on a 1983. Most
shops turn me away because it's too old. 1983 OLD?

A friend suggested adding some Doctor (I forget the name)
that comes in a yellow can to the gas, and just take it out
for an extremely long ride. Another said it was a minor
adjustment to the valves.

What do you think?  

Answer
Hi Marcus,

I think the fuel in the float bowls has varnished and is obstructing the pilot jets and passageways. This is very common with MC's left parked or stored for awhile.

Other considerations are sluggish starter motor. This is normal wear. Carbon brushes wear and the resulting powder collects inside the motor housing. Also, commutator and plain bearing wears adding to the mix. With the age of the MC, maybe the starter motor needs cleaned and new brushes?

I recommend an altenator output test to determine the condition of the electrical charging system. Simple test with a multi-meter (volt-ohm meter).

Avoid fuel additives as a fix. Ok to use gasoiline stabilizers, but follow dosage directions carefully.

Send me an email. I'll return several repair and test information files that should help you. Buy a Clymer's Repair Manual for basic repairs and maintenance. My files give you the tech's scoop beyond the manual.

My email addy is: mshively1@woh.rr.com

Respectfully,
Mark Shively
Dayton, Ohio