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Undercharging due to a stuck starter solenoid?


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Hello all,

 

Has anyone come across this before? My 1997 had been undercharging for the last couple of years (whilst it was shed-bound...still is...but progress is being made to get it back on the road!). We're talking about 13.3 volts at 3000rpm...not quite enough. 

 

Anyway, during my lunch break today I went out and threw in a new reg/rec which I had bought as a spare thinking that, as is usual with these Viffers, reg/recs are consumables! While putting in a new battery there was sparking coming from the negative connector and the starter was being turned. I hadn't even turned the ignition key, it was like the bike was possessed 😁.

 

I thought, maybe the starter solenoid is stuck so I swapped in a working one from my other VFR (800 VTEC). Bike fired up and I had a solid 14.5 volts through the charging system. Perfect. I then removed the "new" reg/rec and put in the older one which I had assumed was faulty and I got the same readings...14.5 volts! 

 

So....could the bike have been undercharging all this time due to a duff starter solenoid? Studying the wiring diagram to refamiliarise myself with the system (I used to know it blindfolded!) everything kinda runs through the starter solenoid so if that's stuck on then it seems there's the potential for that to explain the undercharging. 

 

Any thoughts?

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I’m convinced, you’re good to go now! Starter is an enormous load/draw, not likely any R/R could keep a steady voltage going while it’s cranking away….

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Not something I've heard of in almost 25 years around VFRs. We know the starter solenoid connector sometimes gets fried, how did yours look?

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If starter-solenoid was stuck ON, starter would run 100% of time, even when you've shut off bike, hopped off and walked away.

 

That spark was from installing battery-cables, some cable got tapped to wrong terminal. If you put original solenoid back on, you'll find it works perfectly fine and battery will still be charging at +14v. Charging and all power to bike's electronics actually doesn't go through solenoid itself, only power to starter does. Everything non-starter goes through 4-terminal red connector plugged into solenoid, power bypasses solenoid through fuse.

 

Undercharging was probably bad solenoid connector. Honda's low-end spec of bare brass connectors corrodes over time and increases resistance. Turns power that should've gone towards charging battery into heat.
uc?export=download&id=1huujlbdjS314aaTr9

 

You temporarily "fixed" problem by unplugging and re-plugging that connector and clearing off some corrosion. But it'll be short-lived. Should inspect that connector closely and replace with one using plated terminals. Did this 10-yrs in on my '86 and it's now 37-yrs old with no charging or starting issues ever. Also went to series-circuit RR recently, so much cooler and saves stator from running 100% full-time and frying itself.

 

uc?export=download&id=106bsc0DSJ0Y-il-KP

 

BTW - highest-rated 1/4" spade connector I could find is 24-amps. Honda uses it in 30-amp circuit..

 

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Wouldn't it be better to not run the charging current through the solenoid? There are wiring looms that do away with that feature and run a wire straight from the rr/reg to the battery.

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I have had a stuck starter solenoid - twice.  It's nothing like a subtle power draw.  As @DannoXYZ says, the starter stays on.  And on.  And on.  I was lucky the first time, the bike was on the center stand.  The second time, on the side stand in gear and it kicked itself over.

 

The only way to stop the pain is to disconnect the battery.  So, no...you do not likely have a stuck solenoid 😄

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All great comments folks, it's your contributions which make VFRD such a good forum.

 

The reason why the bike wasn't always attempting to start itself was because, while in the shed, I'd just remove the battery so there was no power. 

 

The connectors to the solenoid looked good, no melty bits like I've seen before, all connections seemed good. It's actually part of a VFRness I installed back in 2014. That said, I'll take a closer look at them this week and ensure they're good. 

 

Anytime I was testing the bike I'd throw the battery in and hadn't noticed the sparking before but the R/R was certainly not pumping out 14.5V but it's passed any diagnostic test I can throw at it (which isn't much, just testing with a multimeter on the bench and then on the bike itself along with a new one to see how that'd do).

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Yeah, diode tests for old selenium rectifiers no longer work on modern RR. That's because regulator stage comes after rectifier. No way to measure rectifier diodes without taking thing apart. It's usually power transistor that fails in regulator stage anyway. Only test is to measure output voltage (assuming that stator is good).

 

uc?export=download&id=1-0h_n18p8jF0EtpgP

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Hmmm some interesting comments here. I did order a new starter solenoid, fitted it last night, that allowed me to take a good look at the old one. Looks fine on the outside, nothing melting anywhere and the wiring looks fine. 

 

I'll try test it out later on. I'm in the middle of rebuilding it at all now, this charging issue was the main piece of puzzlement for me. 

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On 2/10/2023 at 3:35 AM, fabio222 said:

While putting in a new battery there was sparking coming from the negative connector and the starter was being turned. I hadn't even turned the ignition key, it was like the bike was possessed 😁

Hi Fabio.

The Only way this can happen is for the main B and M terminals to have wielded together internally, OR you have developed a short between the Red and the Yellow/Red wire, this could be an intermittent or permanent short that will energise the Starter Relay solenoid. You need to peel back the tape insulation of the Starter red plug and closely inspect these wires. See attached pictures.

 

The Red wire can develop enough heat that can travel up the wire which can melt its insulation if the spade connection for the Red wire becomes poor or high resistance.

 

Info - Also when refitting a new starter relay make sure the B terminal goes to the Battery and the M is the lead to the Starter Motor

 

20210626_091316.thumb.jpg.0375d8c7a8d761429fc630069d9e2e76.jpg

VFR-StartCircuit2.thumb.jpg.c6ea47a0cc969db8dd4b79b49d9da063.jpg

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55 minutes ago, Grum said:

Hi Fabio.

The Only way this can happen is for the main B and M terminals to have wielded together internally OR you have developed a short between the Red and the Red/Yellow wire, this could be an intermittent or permanent short. You need to peel back the tape insulation of the Starter red plug and closely inspect these wires. See attached pictures.

Info - Also when refitting a new starter relay make sure the B terminal goes to the Battery and the M is the lead to the Starter Motor

 

20210626_091316.thumb.jpg.0375d8c7a8d761429fc630069d9e2e76.jpg

VFR-StartCircuit2.thumb.jpg.c6ea47a0cc969db8dd4b79b49d9da063.jpg

Great post, really helpful, thanks for putting the diagram in too!

 

I went out to the shed and took a look, peeled back layers of insulation tape and the wiring to the connector all looks good. I don't have the fuel tank hooked up so can't actually start the engine right now to check voltage but I'll give it a shot later. 

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Had another good look through the connectors and they look all good. I think I'll have some time to swap in the old solenoid this afternoon and just see what happens.

 

Would it be possible that a weak battery may have caused the R/R to look faulty (ie undercharging)? At this point it seems it's either the starter solenoid or the battery. I'll replace both anyway. 

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Also replace everything else in charging system:

 

- stator

- RR

- all wiring between RR and battery

- fusebox

- all wiring connected to fusebox

 

Any one of these items having issues would cause undercharging of battery.
 

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Finally had some time to get out to the shed and test the charging voltages again.

 

I had a solid 14.5v when I use the new starter relay. I had a solid 14.5v with the old starter relay too.

 

The 4 spade connector to the starter solenoid, part of my VFRness, is in good condition, no melty bits. 

 

Given that the starter relay seems to be fine and all of the other wiring checks out fine, I'm beginning to think the old battery might have been the issue. I conducted the above tests with a new battery whipped from the VFR 800 VTEC. The old battery, I noticed today, was barely making 12.1 volts at rest.

 

 

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