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Yamaha 55 2 stroke twin not charging

D

ducati

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New to me, very old (91 I think) Yam 55. No charge reading, battery is at 12.5 volts running and slightly higher not running. I believe it should read about 14.5 volts if it is charging properly.

The questions is about how do I test if it is the rectifier at fault or the generator coil? Or could it be something else?

I've not had the motor on the water yet but seems to run fine.

Thanks

I should add I boat about in the Pentland Firth so it aint going anywhere untill I'm 100% happy with it! :eek:
 
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I have the same motor, mine is a 95 model. I just bought it from a local shop. I saw the same voltage you are seeing so I called the shop. They told me that if the battery is fully charged it will not show more than 12.8 volts. I thought they were trying to dodge the issue, but I bought a shop manual and it says the same thing. To have more than 12.8 volts, the battery has to have been discharged and if you have a good battery and it starts right up, you probably won't see more than the 12.6 to 12/8 reading. My previous Mercury 25 would show 14.5 volts at WOT no matter the battery state.
Mine runs good, but since the weather turned cold I can't get it started. It trys to fire and dies out. I've managed to run the battery down trying to start it, so if and when I get it started I should see if it is charging or not.
 
I got my 95 Yammy 55hp running now. I would never have believed the trouble was a corroded + battery terminal. Apparently there was enough voltage to turn the motor over, but not to fire it off. Once I took off the wing nut, cleaned all the parts, and replaced the wing nut with a locking nut it fired right up. Mine will not show over 12.8 volts until I get over 3000 RPMs. Then it varies from 13.5 to 15.5. I will repeat myself by saying according to my mechanic and the owner manual, it will not charge if the battery is fully charged. The manual specifically says you cannot test the charging circuit using a fully charged battery.
 
Wires typically break as the exit the timer base. From the advance and retard action of throttle usage. Maybe two green wires with a blue cover. Also make sure the green wires go to the rectifier, if any. Manual model's did not have the rectifier. Yhank's Martin
 
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