1970 T250 charging issue

[biggziff]

My 70 T250 has a little charging problem. When I start it with a battery connected the battery starts to boil within a minute or less. I'm assuming it's over charging severely. It's my understanding that this bike only has a rectifier and we did replace the stock one with a generic rectifier many years ago so I'm not sure if that's the issue or not.

So...does my diagnosis sound correct? If so...what is a recommended replacement for the existing rectifier?

Thanks

[jabcb]

Noticed the bike pic in your other post. Its definitely nice.

You are correct that the bike has a only a rectifier & uses the battery as a voltage regulator.
The alternator also has a lighting coil which is switched on/off with the headlight switch.
This increases alternator output when you turn the lights on.

The wiring diagram is here:
http://smokeriders.com/diagrams/Suzuki/ ... 50_350.gif

Is your battery boiling problem occurring with the lights on?
Did you do any recent work where you had to unplug some of the wiring?

The bike could be ok & you might just have a bad battery.
With everything off for a while, what is the resting voltage of the battery?
Will the battery take a charge if you hook it up to a charger?

I recommend that you do not turn the lights on until you have this problem resolved.
Your headlight is extremely hard to find & can be quite expensive. I've seen NOS headlights for your bike go for around $200 on eBay.

Good idea to do a little testing before you replace the rectifier.

Have a couple of choices for rectifier replacement.
NOS stock rectifiers are still available for around $100.

Oregon Motorcycle Parts has a new modern rectifier for $21.
http://www.oregonmotorcycleparts.com/rectifiers.html

You can upgrade to a modern rectifier/regulator for around $50.

New wiring connectors are available so you can replace the wiring that is lost by going with a modern rectifier or rectifier/regulator.

[biggziff]

Noticed the bike pic in your other post. Its definitely nice.

You are correct that the bike has a only a rectifier & uses the battery as a voltage regulator.
The alternator also has a lighting coil which is switched on/off with the headlight switch.
This increases alternator output when you turn the lights on.

The wiring diagram is here:
http://smokeriders.com/diagrams/Suzuki/ ... 50_350.gif

Is your battery boiling problem occurring with the lights on?
Did you do any recent work where you had to unplug some of the wiring?

The bike could be ok & you might just have a bad battery.
With everything off for a while, what is the resting voltage of the battery?
Will the battery take a charge if you hook it up to a charger?

I recommend that you do not turn the lights on until you have this problem resolved.
Your headlight is extremely hard to find & can be quite expensive. I've seen NOS headlights for your bike go for around $200 on eBay.

Good idea to do a little testing before you replace the rectifier.

Have a couple of choices for rectifier replacement.
NOS stock rectifiers are still available for around $100.

Oregon Motorcycle Parts has a new modern rectifier for $21.
http://www.oregonmotorcycleparts.com/rectifiers.html

You can upgrade to a modern rectifier/regulator for around $50.

New wiring connectors are available so you can replace the wiring that is lost by going with a modern rectifier or rectifier/regulator.

Is it considered a good idea/upgrade to change it to a rectifier/regulator? I'm not likely ever going to sell this bike and would like to ride it a bit this year so I don't mind spending a little money on it.

The battery is questionable, but it did take a charge last year. It does have a cell that would empty of fluid if left on trickle charge (It's a cheapie lead/acid battery) I'm going to replace it this year as they're pretty cheap to buy. Is it best to stay with the lead acid or go to AGM?

I had the lights on and off, but it would act weird where the lights would work and then they wouldn't. Bike hasn't been ridden in many years....no modifications to wiring since installing the replacement rectifier in the 1980s.

Thanks for your reply and kind words on the old bike. I'm going to take it to a few shows this year towing it behind my Ural Gear Up. Should turn some heads.

[jabcb]

Looks like you have a bad battery.

Rectifier might be ok. Can be tested if you have a multimeter.

Have two basic choices:
1) if you continue with just a rectifier (existing, stock replacement, or modern replacement), then you need to use a conventional battery like the cheapie you have.
2) if you upgrade to a modern rectifier/regulator, then you can use a modern battery (sealed maintenance free, AGM, …)

Both choices are reasonable.
Both of my T350s are stock (rectifier only + cheapie battery). My GT250 is upgraded (modern rectifier/regulator + AGM battery).

For your lighting problem, do all the lights stop working or is it just the headlight?

[biggziff]

Looks like you have a bad battery.

Rectifier might be ok. Can be tested if you have a multimeter.

Have two basic choices:
1) if you continue with just a rectifier (existing, stock replacement, or modern replacement), then you need to use a conventional battery like the cheapie you have.
2) if you upgrade to a modern rectifier/regulator, then you can use a modern battery (sealed maintenance free, AGM, …)

Both choices are reasonable.
Both of my T350s are stock (rectifier only + cheapie battery). My GT250 is upgraded (modern rectifier/regulator + AGM battery).

For your lighting problem, do all the lights stop working or is it just the headlight?

I don't remember what lights stopped working as it was last fall. I have several DVOMs (Flukes), but I'm not aware of a test procedure or specs to test to. Can you assist with that data or a link to same?

thanks!

[jabcb]

This wiring diagram is for a GT250B: download/file.php?id=826
Wiring is similar to yours except the GT250B has a voltage regulator.
This diagram shows the rectifier design & how its wired up.

To test rectifier:
1) check the resistance between Y/G wire and ground (Y/G wire connects to alternator)
reverse the meter leads and recheck the resistance between the Y/G wire and ground
you should get high readings for one test and low readings with the meter leads in the other direction

2) check the resistance between R/G wire and ground (R/G wire connects to alternator)
reverse the meter leads and recheck the resistance between the R/G wire and ground
you should get high readings for one test and low readings with the meter leads in the other direction

3) check the resistance between Y/G wire and red wire
reverse the meter leads and recheck the resistance between the Y/G wire and red wire
you should get high readings for one test and low readings with the meter leads in the other direction

3) check the resistance between R/G wire and red wire
reverse the meter leads and recheck the resistance between the R/G wire and red wire
you should get high readings for one test and low readings with the meter leads in the other direction

[biggziff]

Thanks!