hi guys i am new member to this sight.i just bought a 1985 vmax and i am having a staring issue/charging.so here is what i know i place trickle charger on it over night it is charged to 12v and i get 4-5starts and then battery is to weak to satrt bike so i believe it is not charging properly. i found my rectifier but is not stock as connectors are cut off and the 3 white wires are soldered directly to white wires from stator and a red one that is plugged in with a connector. the rectifier on the back is stamped 42x-a0 ,sh569-12 ,5.3.1. acoording to wire diagram it should have a black wire for the ground but this rectifier only has 3 whites and 1 red. so how do i test this thing with multimeter to see if it is pooched. i also measured resitance across white wires on stator and got 0.5 ohms is it ok? please any help that can be given would be appreciated. i have a solid state rectifier for a 78 cb550 i bought from oregon bike parts that is a 5 wire 3 yellow 1 red and 1 green which is ground can this be substituted in? i want to get this bike back opn the road i love riding it but don't want to be left stranded with dead battery.
Help Support VMAX Forum:
Bill Seward
Well-Known Member
Sounds like you have an original R/R unit. There is no ground wire. They grounded through the frame. Poor design, as corrosion plays hell with the connections. The 3 white wires soldered to the stator wires is a good thing, as in my case, the plug corroded, got real hot, and melted one day. If you're not getting 14+ volts to the battery with the engine running, you may have a bad R/R. You can check for stator output by measuring voltage across any two wires, doing all combinations of wires. You'll be measuring AC current, and, if I remember right, you should see over 40 volts or so. (someone else may add the proper voltage here, if my memory is wrong on this...)
If AC volts is OK, and you are not charging, the R/R unit is probably kaput. There are any number of aftermarket units out there, and a lot of posts here on how to fix it. DON'T buy a original unit from an early Max. You want a ground wire. I used an Electrex unit (less than $75.00 online). I connected the red (+) and black (-) wires DIRECTLY to battery. This will make the electrons path to charge that battery as direct as possible. No 25 year old connectors to fight their way through...
Almost any newer Yamaha R/R unit with the 3 white wires, and a red & black pair will work. You may have to be creative in mounting it, as it probably won't mount as stock.
The unit I bought fit as original. Evidently, the newer units use a different method of voltage control, and they don't get nearly as hot in operation.
You'll have to connect and maybe lengthen wires to get the power to the battery. You'll definitely have to connect the 3 white wires to the stator. (These connect any way - there is no "right" way or "wrong" way to do it) Anyway be sure to SOLDER everything. Those crimp connectors you buy at the hardware store will fail in a year or so. Heatshrink every connection so there is no chance of short circuit.
I've had an '85 since it was new, and this change to the upgraded R/R fixed charging problem once and for all...
Think about the battery box modification to use the Gold Wing battery, if you're replacing a battery down the line. Simple to do, and the bigger battery kicks ass!
If AC volts is OK, and you are not charging, the R/R unit is probably kaput. There are any number of aftermarket units out there, and a lot of posts here on how to fix it. DON'T buy a original unit from an early Max. You want a ground wire. I used an Electrex unit (less than $75.00 online). I connected the red (+) and black (-) wires DIRECTLY to battery. This will make the electrons path to charge that battery as direct as possible. No 25 year old connectors to fight their way through...
Almost any newer Yamaha R/R unit with the 3 white wires, and a red & black pair will work. You may have to be creative in mounting it, as it probably won't mount as stock.
The unit I bought fit as original. Evidently, the newer units use a different method of voltage control, and they don't get nearly as hot in operation.
You'll have to connect and maybe lengthen wires to get the power to the battery. You'll definitely have to connect the 3 white wires to the stator. (These connect any way - there is no "right" way or "wrong" way to do it) Anyway be sure to SOLDER everything. Those crimp connectors you buy at the hardware store will fail in a year or so. Heatshrink every connection so there is no chance of short circuit.
I've had an '85 since it was new, and this change to the upgraded R/R fixed charging problem once and for all...
Think about the battery box modification to use the Gold Wing battery, if you're replacing a battery down the line. Simple to do, and the bigger battery kicks ass!
Bill Seward
Well-Known Member
Did a bit of looking...
Google "Electrosport". They sell R/R units.
Get one for the VMax, but the one that fits the 1989 - 2007
ESR280. This is the one I use. You will notice there is a ground wire.
Costs about $75.00, same as I paid a couple years ago.
Welcome to the forum, by the way!
Google "Electrosport". They sell R/R units.
Get one for the VMax, but the one that fits the 1989 - 2007
ESR280. This is the one I use. You will notice there is a ground wire.
Costs about $75.00, same as I paid a couple years ago.
Welcome to the forum, by the way!
2fear
Well-Known Member
I bought one from Python motor last year for my 85.
ok so i tested my rectifier and got the following values: grond lead on red wire and red lead on each white wire i got 1.6mega ohm,42.5 k ohm,1.7 mega ohm.reversed the leads and got similar values.now correct me if i wrong but all the values should be the same and you shouldn't have continuity in both direction right? either way i have a 55 amp 5 wire rectifier that has 3 whites and a red and ground wire i can take straight to the battery and try. thanx again guys.
well i would like to reort back success. my vmax at idle is putting out 13.5-13.6v and as i rev it up to 5 rpm i get a gradual increase up to 15.5v but at around 2000rpm it sits around 14.5v which i think should cure my dead battery issue i was having after 4-5 starts. the rectifier i used is off a honda cb550 that i bought from oregan bike parts for around $40 and will handle up to 55amps and alllowed me to run a positive lead and ground straight to the battery ,it fits in stock position i just had to make a mounting bracket to attach it to.it was a good day.
![Bovemanx Motorcycle Phone Mount Holder, [150mph Wind Anti-Shake][7.2inch Big Phone Friendly] Bike Phone Holder, Motorcycle Handlebar Cell Phone Clamp, Compatible with iPhone 16 Pro Max Smartphones](https://m.media-amazon.com/images/I/51F+1sontPL._SL500_.jpg)
Bill Seward
Well-Known Member
Good Job!
This forum is a true gem for VMax owners. There is a lot to be learned here, a lot of cool people here, too!
You're gonna be fine now. Go for a ride!
This forum is a true gem for VMax owners. There is a lot to be learned here, a lot of cool people here, too!
You're gonna be fine now. Go for a ride!
that i will right after the rain subsides but for now i will take pleasure in seeing the lights run bright and listen to it run.i have to say i was a little intimidated by this bike when i frst test drove it to buy earlier this week especially coming off a 84 vt750 what a difference in power.but the more i ride it the more i absolutely love it. i just want to make some cosmetic changes as i have seen pics here of them in completely black and wow....
Redbone
Well-Known Member
Good job on the repair and welcome.
Just a note, watch out for random banana peels in and around your garage. The mod monkey can show up in many disguises, for example, one showed up in Southern Australia as a hard living country western singer.
Attachments
Bill Seward
Well-Known Member
Redbone:
Gotta love blondes!
Gotta love blondes!
richwrench
Well-Known Member
If you like the blacked-out look, check out KJ Shover's bike in the garage pics - BadAzz ! I'm thinking of doing that myself...
