Trying to figure why she wont start once warm?

Just been doing more testing to try to figure out why my 94 VFR750 wont re start at running temps.

Starting with a fully charged and relatively new battery ( on charge for 4 nights)
I checked the battery with ignition off and reads 12.81 vdc
with the ignition on reads 12.00 vdc (lights are on as they are hard wired on)
after cold start and warming to idle reads 14.6 vdc (at idle of 1100+rpm)
at 2500rpm reads 14.02 vdc
at 4000rpm reads 13.9 vdc
at 5000rpm reads 13.85 vdc
and at 7000rpm reads 13.84 vdc

then I unplugged R/R
idle 1100rpm reads 12.02 vdc with lights on again

plugged R/R back in and at idle reads 12.8 vdc now

stopped and turned engine off, now she wont re start, doesn't seem to have enough juice in the battery to turn over.
Makes the noise a flat battery makes when it hasn't got enough power to crank the engine over fully.

I have checked the stator and that looks good, starter relay is good as is 30 amp fuse.
All connections for the charging system are cleaned and fitted with dielectric grease.
Noticed the wiring from the starter relay seemed to have been re wrapped with electrical tape, so unwound and discovered above wiring.

First question: is the blue tape covering the joined wires standard? and are these joins standard on the 4th gen?
The join with the green wires involves the green(earth?) wire from R/R

I am wondering if there could be a short here with these two crimped joins?
Any help would be greatly appreciated.

 

looks like some homebrew wiring, you may want to look into a VFRness at wiremybike.com

 

Ugh, not only did your PO not solder his wires, he didn't even bother to tape them up, just crimped them.
Hot start issue: did you check the measurements on your stator? Done valve clearance measurements lately?

 

You must have missed the before pics above with the blue tape on the wires
What will valve clearances change for hot starting?

 

This crimping and blue tape is something I also found in vf1000f wiring harness I dismantled.

I had the same starting problem with a vf1000f, I found the starter huge cable was loose in the connector bolted to the starter.
I assume engine heat in the area caused expansion of the connector and weak contact.
I could pull out the cable by hand.
I fixed the problem by soldering the connector on the cable with a propane torch (cable is something like 3 gauge).

 

Thanks and will check this cable again although seems pretty good.

 

Hey Sruss...That looks like standard Honda splicing to me. Really...I think you're 'barking up the wrong tree' with those small wires. At any given moment in time (when the button is pressed), all the high current is carried on the big cables and starter relay. Of course the battery has to supply the power, so if your charging system isn't keeping it up...well...that's where those small wires might come into play. That's the relationship. BTW, your PM box is full. DZ

 

Yeah, your voltage should not be going down in higher RPMs. You need larger gauge wiring for one. As was mentioned, check out Wire My Bike for a more robust harness.

 

A battery when fully charged should be between 13.2 and 13.8 volts.
IT has six cells and each cell is about 2.3 volts. Yes...I know they call it a 12 volt battery.

When the engine is running, and most modern bikes have the lights on when running, the volt meter
should read about 14-15.5 volts something like that. Check the workshop manual for YOUR bike.

The wire for a starter to the solonoid or battery needs to be at least 6 guage wire.

Your battery sounds like it is bad.
It will not start when warm because it is not getting charged. It starts from the full charge and just continues to drain as it runs because
nothing is being put back into the battery.

 

when you do replace your battery (and whatever else is causing the poor charging) do yourself a favor an install a battery tender. I am still on my orig battery and R/R despite be bike being 18 years old. If it's not on the road, it's on a tender.

 

just a thought..... doesn't the battery, by being on a charger all the time create battery memory? you know like rechargable ones do? we had this problem with radio batteries the would only last a few hours then "die" ... our radio guy said this was due to us keeping the radios on the charger when not in use, nad not discharging the battery all the way down before re-charging them.

 

possibly, I am just speaking to results on every bike I have owned (the 92 being the longest). I have never (knock on wood) had a R/R or battery/charging system failure due to religious use of a battery tender. Ducati's have R/R issues just like VFRs so while the science escapes me, the results are clear. I cant in my wildest imagination understand why folks resist a $32 battery tender - in light of $50-70 batteries, $115 rectifiers and $120 stators...

my bike start on the first time, every time and are running the OEM parts. Plus a fixed battery tender leash when unplugged powers my tank bag with XM, GPS, Cell Phone and Valentine1 on a custom harness... unplug bag, plug in tender, sleep well.

Sorry to rant, but battery R/R and Stator issues are everywhere - if folks invested $32 they could ride more and whine less

 

You cannot diagnose ANY electrical problem until you have a SOLID source of "12" ...(13.8)volts

 

As usual I don't agree with all of Don's post. I'd say your charging as posted is fine and it's normal to see a bit of variability in VDC with RPM. Usually I see a slight decrease with higher RPM. I think voltage on a good fully charged battery after a day or two of rest should be around 12.6 or a little more.

But...VDC doesn't tell the whole story on battery strength. I agree with Don that your battery might be suspect. I wonder what the VDC drops to when the failure occurs AS your presssing the starter button. Kind of a 'home spun' load test so to speak. Or you could bring your battery to a dealer or battery purveyor and have it load tested.

 

Hi DZ and good to hear your thoughts.
When I did the testing I did do the test you suggested last time which was to check voltage across the battery terminals when the starter was engaged.
Looked to drop to 9-9.5VDC.

If I remember correctly this was too low?
I think I will buy another battery and go again.

Looking at batteries is it best to go with the Yuasa YTX12AH-BS? or is there a better battery I can fit?
By the way I have a charger/battery tender unit to use now as well, so no chance of incorrect installation this time
Thanks

 

If it were me, I'd go with the Yuasa. Other batteries maybe fine as well. If you're servicing it, make sure to use the acid that comes with it (higher specific gravity than 'run of the mill acid). Let it rest for around an hour after you fill it. Then let it sit on your tender for a day or so...should be ready to go.

 

Went to local Honda dealer today to enquire re Yuasa battery.

Sorry mate we dont stock them as they are oem and expensive, hmmm humour me with a price I said. $652aus for a f*&^%n battery!!!!!!!

They have got to be kidding me, who the hell makes all the money from a sale like that?

So Yuasa looks out of the question at the moment, will look to see what other options there are and must call Yuasa Aust agent to enquire re price also.

 

Just looked at dealers for the Yuasa battery online and $159, how the hell does Honda justify $652 for theirs?

 

someone has to line their pockets it wouldnt be the world as we know it if they didnt.... no wonder the world as a whole is in such dire financial distress... i think an appy will be my next new bike..

 

Wow...there's gotta be a story behind that $652 quote. I think $150 is bad enough.