Yamaha 350 single help needed

Hi Folks! Once again i'll try to tap into the collective wisdom of this
group as its been very helpfull for my KZ & GPz problems.

My future son in law has got a 1987 Yamaha Warrior quad. Its a 4 stroke 350
single. He has stripped and repainted the frame (I mention this in case
theres an electrical ground issue suspected) He has reinstalled a 1993
engine, from a warrior as well. He also had to change the entire wiring
harness as the 87 engine had a different plug and less wires coming from the
stator. He used a 93 harness from the bike that gave up the donor engine.
Now the engine will not produce any spark when cranked. Checked all the
usual culprits, plug, wire, coil with no success. We have no way of
testing/checking the cdi as its different than my bike (a 2002) however on
my bike we can register voltage coming directly from the stator.When
attempting to measure voltage coming directly from his stator we get
nothing. He's installed a brand new stator and pickups but still nothing
reading when its cranked over. We tried measuring for current both with the
wiring completely hooked up, and as well, with the stator unplugged from the
harness.

Any ideas/hints/suggestions???

TIA !
Tom B

 

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I would suspect the ground.

Motor mounting places, where the frame and the engine contact should
be polished to clean metal, free of corrosion, paint, and debris.

You should have a good clean contact point where the battery's ground
wire is bolted down.

Good Wrenching to You!

..


Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF

 

If you're getting no spark but still able to crank, take a look
at the tach. If the tach shows RPMs when you're cranking,
then the CDI is probably doing its job. If the tach stays
absolutely flat, the CDI unit or trigger may be in trouble.

If it's not the CDI, is there voltage to the ignition coil primary ?

I'm not at all sure what you mean by "voltage from the
stator" or why you're looking at it. Are you worrrying
about a trigger signal or charging ? I'd expect that
it'd be able to fire off the battery even with the charging
system broken.

Besides the ignition system and coils, you should also
take a look at any unconnected wires and any safety
interlocks that were present on the later model. It's
very possible that you might have a problem in kill
switch wiring or some other safety feature such as
a clutch interlock.

Best of luck.

 

thanks for the replies folks!

Wudsracer, we will check the ground aspect first as he did NOT clean the
paint off the engine to frame mounting surfaces prior to engine
reinstallation.

Rob, no voltage going to the coil, no tach to check while cranking either
btw. We're looking at the stator, pickups trigger as a source of the problem
simply because we've more or less eliminated all else. Tried a cdi from my
bike which runs, then runs again when we re-install in mine, so our
assumption (I know I know about assumptions!) is its got to be a problem
originating at the source. Wiring harness has been gone over with a fine
tooth comb and even swapped for another, kill switch has been bypassed,
reconnected, bypassed again etc.

Tom B

 

Let me clarify this.....MY bike runs with the cdi in it, his does NOT and
will not with my cdi