1982 Yamaha 650 - no start

Good Evening!

My nephew called me last night. The bike he just bought won't start.
I'm going to try to help him get it going again, and thought I'd do a
little research first. I've read the posts related to no start
conditions, but I thought I'd also post a message here too. One thing
I know I'm going to need is an electrical diagram - does any one have
one that they'd be willing to share, or is this something that only
comes with the shop manual?

He said it was having electrical problems. He mentioned that it got
wet, and hasn't started since. Electric start won't work at all. Kick
start yields just a sputter.

My plan is to do a complete electrical inspection - grounds, fuses,
look for corrosion, etc. One of the posts I've read indicated that
there could be corrosion in the iginition switch - can that be taken
apart? Once I'm satisfied that all connections are solid, I'll start
with spark test, fuel flow (gravity feed?), other basic checks, etc.

Is there anything these bikes are notorious for?

Thanks!
Doug

 

If the battery is old and sulfated, it may not produce enough voltage
to
operate the transistorized ignition system. Transistor ignitions are
dead stone reliable, they either work, or they don't.

Most newbies don't know how to "choke" a motorcycle with constant
vacuum carburetors. Since there is NO flat choke plate like a car has,
you have to leave the twist grip alone when starting. Just pull the
"choke" knob or move the "choke" lever to the full ON position and
crank the engine.

Usually not. But, if you work the ignition switch through all of its
positions several times, it should clean the contacts itself.

Yes, most motorcycles of that era had a gravity feed system. Many had
a vacuum-operated automatic shutoff petcock. If you see the letters
PRI by the petcock knob, that's the PRIME position, and it will fill
up the carbs even if the engine isn't running yet.

Yes, they were notorious for being bland and boring, so they were
called
"Universal Japanese Motorcycles".

BTW, does he have the twin or the 4-cylinder 650?

 

Engines in general are notorious for not running (good) if the battery is
dead.
I suggest you test that........and the main connections .......before you
waste a lot of time on other things.

Except for the safety interlocks, kill, clutch, neutral, side-stand, a bike
engine is really no different than a small car or a big lawn mower.

 

Thanks for the replies. I'll start with the items you both suggested!

Doug

 

lol! He has the twin.

 

It really helps us if you state in your very first message which model
you're having problems with.

The XS650 started out as a very simple machine, apparently a sort of
Japanese Triumph twin, but actually based upon a defunct German
design.

Then the XS650 began to get weirder as various electrical interlocking
gizmos were added...

Go to this link and look at the typically weird electrical components
that only Yamaha would use:

http://www.powersportspro.com/pages/parts/viewbybrand/default.aspx

Look at Electrical 1 and Electrical II.

Like, there is a side stand switch *and* a side stand switch relay to
complicate the electrical system. There is a relay that seems to
defeat the starter. There is also something called a "reserve lighting
unit".

If you look at the AC generator, you'll see that it is a brush type
alternator. There is a Hall Effect sensor on that drawing. It triggers
the transistor ignition unit.

 

Ignore Krusty as he really doesn't have any knowledge of these bikes
beyond what he can glean from poring over a schematic or Googling.

They're incredibly tough bikes. The engine is as strong as anything.
The weak point is the electric start, or to be specific, the starter
clutch. A lot of people junk the e/s, and you can buy a blanking plate
that fits over the hole.

Anyway, if it's been standing, then the fuel will have gone off and
partially blocked the carbs. PITA, but fixable. If it's really, really
badly gunged up, then ultrasonic cleaning is really the only sure fix.
Assuming that it hasn't been standing, and has new fuel and a new
battery and new spark plugs: are you getting a spark? If it's
sputtering, that suggests that there's some form of ignition
happening. Generally, though, electronic ignition systems either work
or they don't. There's no in-between. Earlier models of the XS650 had
contact breaker points, and different rules apply there.

If there's no spark, then it could be the ignition switch or the kill
switch. It's more likely to be corroded connectors in the loom,
however. But if it got wet, and was running fine beforehand, I'd
expect it to run after being dried out. If the switch is corroded,
then turning it on and off a few times won't cure it properly,
whatever Krusty says. Think: if turning it on and off got rid of
corrosion, well, it would never get the chance to corrode ever, would
it?

I've just had to strip down an ignition switch for a 1977 Honda. I
cleaned it thoroughly with very fine wet & dry paper and contact
cleaner, bent all the little springs and contact points a fraction so
they made better contact, reassembled, and it was perfect. Top tip:
dismantle it inside a large transparent plastic bag, because these
switches are full of pingfuckits, and when you pull them apart, tiny
springs and ball bearings can fly everywhere. Same goes for the kill
switch, although it's easier just to bypass this.

If it's totally dead, bypass the sidestand ignition cut-out switch.
These bloody things always give trouble when they get older. I've just
had to bypass the one on my 1991 XT600E dirt bike.

Fuel flow is gravity feed, so no whahala there.

Seriously, it's a very simple basic bike, and the basic checks should
soon isolate the problem.

Mechanically, as I said, no weaknesses. Camchain adjustment is 100%
manual, and must be done properly. Also, be warned that it has not
one, but two oil drain plugs, and two oil filters: one in the sump,
and one behind the circular cover on the right-hand side of the
engine. These are both washable mesh filters. The big one in the sump
has a reputation for breaking up, though.

Finally, Yamaha always recommended 20/50 oil for the 650 twin, not the
much more common 10/40.

They are wonderful bikes. I've owned (counts on fingers) four, and I'm
sure I'll have another one day.

 

well, I didn't realize there was more than one option for the 650.
He's had the bike for about three weeks now, and I hadn't seen it
until tonight. Had I known there was a twin and a 4 cylinder option, I
would have specified that.

Just got home from his house. The battery was completely dead. Very
low water. After charging the battery for a bit, I was able to get it
started. I took it for a short ride, and it is runs very strong. He's
buying a new battery tomorrow. I'll be walking him through the basics
this weekend, and the suggestions and pointers offered here will
definitely help!

Now my next challenge is to get one for myself, but I'll have to work
on the wife first!

Thanks again everyone!

Doug

 

Oh just go for it. She'll get over it........or she won't. Either way you
win! ;-)

 

I like your way of thinking!

 

It's invariably the simple things that stop an engine working....

 

Tell him to buy a maintenance-free battery. It won't need water for
six or seven years.