Low voltage reading and dim lights ?

ArronA · Post by **ArronA** » Sun Sep 11, 2016 3:45 pm

Hi guys this morning i finally got my bike running which I'm absolutely thrilled about! i explained in a previous post that i brought the bike as a project and it was running awfully and today is the first time since I've owned it that it appeared to be running fine, however... doing a walk around testing all of the electrics the headlight is very dim so i tested the voltage coming off the battery and it was reading 11.5 volts give or take 0.1 volts which I'm baffled about because I've put a new voltage regulator on the bike, the voltage doesn't increase with the rpm's of the engine neither does the brightness of the headlight so i tried the old reg/rec and the voltage was reading lower! (around the 10 volts mark) i did think a while back the battery was on it's way out because it use to go dead quite quickly when i was trying to get the bike running at first, i've charged the battery several times but now i don't have a battery charger to hand, surely naff battery wouldn't give a lower voltage reading when the engine is actually running ? i also resistance tested the stator and that appears to be fine, could it be the crank pick up? I've 2 of these spare but i think they're off a 600 3HE but they look identical to the one on my 3TJ

I look forward to hearing your replies

Thanks!

ArronA · Post by **ArronA** » Sun Sep 11, 2016 4:50 pm

I don't know if this helps it's a bit of a silly thing to do but i disconnected the battery whilst the bike was running and the engine cut out, shouldn't the magneto and stator give out enough voltage to power the coils and keep the engine running even without at battery ?

I know it's it's not really a comparison but I've a DT125R that will kick over and run without the battery in in the bike, so it's got me thinking that it's something to do with the charging system and not a naff battery

Post by **Evilchicken0** » Sun Sep 11, 2016 8:42 pm

Charge the battery again an measure the volts across it off the bike, then on the bike and finally when it's running but it sounds like either the alternator or the wiring has been fried at some point changing its resistance.

3tj lights are crap though

ArronA · Post by **ArronA** » Sun Sep 11, 2016 10:42 pm

I had to replace the 3 pin plug coming off the stator as the block was melted and one off the connectors was black but i put that down to the reg/rec so put a new one on and also put new spade connectors onto the wires, i honestly would have thought that the bike would still run without a battery and the brightness of the lights would increase with the higher RPM's of the engine but the engine just cuts out so it's obviously not putting out any voltage

Post by **dobbslc** » Mon Sep 12, 2016 9:26 am

Hi. Most four strokes won't run without a battery. Disconnecting the battery while running is not a good idea.
The voltage at the battery can read low if the battery is knackered enough, I had a Toyota Surf that showed only just 12 volts when running BUT it did increase the voltage so I knew the alternator was OK. If yours doesn't show an increase when running there's something wrong with either the stator or it's wiring.
The pickup is nothing to do with the charging system.
Hope this helps.

ArronA · Post by **ArronA** » Mon Sep 12, 2016 9:36 am

That's great, i think it could do with a new battery so I'm going to get one anyway and also I'll test the voltage coming from the stator whilst the engine is running and see what readings i get, I've got a stator from an fzr600 3he it looks identical to the one in my 3tj and has the same connectors on it so it should be the same right?

Post by **Evilchicken0** » Mon Sep 12, 2016 9:41 pm

You want a later genny ... from a T'cat or fzr600r foxeye. . I'm not sure the 3he will fit because it sits under the flywheel were as the 3tj goes in the genny Co er.
The battery makes a circuit on a 4 stroke

ArronA · Post by **ArronA** » Tue Sep 13, 2016 8:41 am

Evilchicken0 wrote:You want a later genny ... from a T'cat or fzr600r foxeye. . I'm not sure the 3he will fit because it sits under the flywheel were as the 3tj goes in the genny Co er.
The battery makes a circuit on a 4 stroke

When i removed the genny from the 3he motor it was screwed to the side casing and the magneto was bolted to the crank just like the 3tj ones are, unless it wasn't a 3he motor as i did get given it buy a guy i know i just assumed it was 3he becuase it had 3he on the inlet rubbers but that doesn't mean anything really

Post by **Evilchicken0** » Tue Sep 13, 2016 2:09 pm

The 3tj alternator is bolted to the cover casing. The flywheel is on the crank.

ArronA · Post by **ArronA** » Tue Sep 13, 2016 5:03 pm

Evilchicken0 wrote:The 3tj alternator is bolted to the cover casing. The flywheel is on the crank.

Yep that's right, the same as the alternator that i took off the 3he engine the alternator was also bolted to the cover casing, i fitted it into my 3tj but it doesn't appear to have made a difference, I'll see what happens when my new battery arrives tomorrow, when doing a voltage output test on a alternator what AC voltage should i be getting from it when the bike is at idle ?

Low voltage reading and dim lights ?

Low voltage reading and dim lights ?

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