1989 Yamaha PRO 50. Not charging?

[James R]

Shows 12.5 volts when revved. Charging coil shows 40 ohms to ground. Rect/Reg shows the same readings compared to a new unit. Battery is new and connections clean. Need help.
Thanks.

 

[99yam40]

Re: 1989 Yamaha PRO 50. Not charging?

Have you checked the ohms (.56-.84 ohms G/W-G)) of the lighting coil or the peak voltage out (8-9 V cranking, 25 V at 1500 )put like the manual says.
I do not remember seeing any spec for ground to coil but I would think it should read open (not grounded or partially grounded)

 

[James R]

Re: 1989 Yamaha PRO 50. Not charging?

Thanks for the response 99yam40. It is the charging coil that I am testing not the lighting coil. They are two separate coils. The greens from the coil common up and the other end of the coil goes to ground. I am certain that there is a resistance measurement as with all coils I just don't think that 40 Ohms is good.

 

[99yam40]

Re: 1989 Yamaha PRO 50. Not charging?

When you say charging coil are you referring to the battery charging part of this motor (lighting coil)or the charge coil that generates the voltage for the spark?
12.5 volts when revved is not enough to generate spark even if it is on the primary side

 

[James R]

Re: 1989 Yamaha PRO 50. Not charging?

Thanks 99yam40. Got a manual. I see the lighting coil is the battery charge coil. The other coil is referred to as a charge coil. Pulled the green splice wire and separated what must be the Tach wire and the charge came up. Could be a bad Tach. In the mean time the motor made a racket and #3 cylinder blew. This one has already been bored to .040 so it is done. Looks like poor lube.
Thanks again,

 

[99yam40]

Re: 1989 Yamaha PRO 50. Not charging?

What makes you think it was poor lube?

Like they say lack of oil will get the bearings first and lean fuel/air ratio will get a piston

 

[James R]

Re: 1989 Yamaha PRO 50. Not charging?

No trace of oil at all the plugs. However the upper two cylinders had more of a fuel trace when the head was pulled. Could be fuel. Will look into having the bad cylinder sleeved. The owner had no maintenance done for two years and had not used stabil so the carbs are due.

 

[99yam40]

Re: 1989 Yamaha PRO 50. Not charging?

A leaking fuel pump can wash some of the oil from the cylinder walls on #3, would be a good idea to check it also

 

[James R]

Re: 1989 Yamaha PRO 50. Not charging?

Ok thanks.