Grinding sound when cranking hot, bad battery?

Hello guys, I had this problem since last year, and this is the situation and what I did and didn't so far.
Last year battery was in better shape, hold charge, but it could drop to 9.6v during cranking, sometimes it won't go below 11v... It wasn't the best.

This problem ONLY happening on hot/hottish start, never EVER on cold start.

What I did so far is:

1. Checked the battery, isn't the best. I need to replace it and I suspect that is the problem but...
2. Check the ground, perfect.
3. Cleaned battery terminals, inspect cables.
4. Cleaned starter relay pins and starter switches.
5. R/R is fine, proper voltage.

What I didn't and should:
1. Change the oil (can that impact the starter clutch)?
2. Change the battery - most important to do just to eliminate that.
3. And ofc I didn't open the case to see the starter clutch and didn't inspect the starter motor cuz, I am not so sure that I can do that (mostly cuz I never done this before), even if Im usually working on my motorcycle, smaller things and services.

Here is the video. First start is ok, and it happens on 2nd and 3rd. My suspect is that because battery is bad, on every other start, it is weaker and weaker and motorcycle produce that sound - not enough power to crank properly?

https://drive.google.com/file/d/1glppXAsErw1zHdbywXvJoQcl7h4qoRew/view?usp=sharing

And what is grinding - starter clutch or starter motor?

Also, what is strange, sometimes I can start it like 10 times in a row without any problems... 
It has something with the temperature, cuz it never happens on cold engine... can the heat affect bad battery? Old oil in the case? Bad starter motor, starter clutch? Check the torque on these 3 bolts on the starter clutch?
 

Sounds like it is time to get a new battery

If you put a load tester on that battery I bet it is history

Very cool to see a 3rd gen with the optional clock, does it have the optional center stand as well?

Time for a battery. 1st start was ok, but it took a charge off the battery that wasn't replaced by running. 2nd time there was a weaker battery and the 3rd was the worst as each time you took from the battery without replacing the charge but running for awhile. A good battery wouldn't be affected by that, and Yes, heat is bad for a battery.

2 hours ago, Hingley

Sounds like it is time to get a new battery

If you put a load tester on that battery I bet it is history

Very cool to see a 3rd gen with the optional clock, does it have the optional center stand as well?

I have the centerstand yes, Thanks.

1 hour ago, jefferson

Time for a battery. 1st start was ok, but it took a charge off the battery that wasn't replaced by running. 2nd time there was a weaker battery and the 3rd was the worst as each time you took from the battery without replacing the charge but running for awhile. A good battery wouldn't be affected by that, and Yes, heat is bad for a battery.

I tried to reproduce today and after 15 restarts, nothing happened. Tried to reproduce it and then connect to car battery to test, but every time it started fine. 

Someone suggested to clear starter motor and also check famous starter clutch. But first, the new battery.

Thanks.

Hi there.  Nothing I've seen or heard says "starter clutch" to me.  When that goes, the bike does not start at all, because the starter doesn't engage and spin the engine like it's supposed to.

When diagnosing VFR charging issues, ALWAYS start with a known good battery.  If it's a few years old and you don't have a battery load tester, just replace it.  Batteries are also relatively cheap!  

FWIW, the video showed me that your battery is weak, but not extremely so.  It should start the bike several times more than that--if it's good.  But it still takes a charge and starts the bike at least three times, which should be fine unless you stall the engine a lot...

(Btw, all non-US/Canadian VFRs of that era came with clocks and center stands--they were removed from the US-spec models for cost reasons, apparently.)

Ciao,

JZH

Try starting it off of another battery or jumped to your car and see if the symptoms change. (amps are pulled, not pushed)

7 hours ago, bmart

Try starting it off of another battery or jumped to your car and see if the symptoms change. (amps are pulled, not pushed)

I tried that before and when I hook up on the car battery, 10 starts, all fine. 

Yesterday I wanted to test that again and I warmed up the bike and I tried to get that grinding sound, then after that I would hook up on the car battery to see. I done 10 starts on my bike's battery and all 10 times were with no problems at all... so I quit that idea to hook up on the car battery to test it. 

If it always works off of a known good battery...that's a strong hint. 

In your video, battery is getting a little weaker with each start attempt since you're not running/riding the bike long enough to fully charge the battery.  I didn't hear anything unusual in your 3 start attempts, suspect the starter clutch is just fine..... you need to get the battery load tested, but sounds like you need a new one perhaps.

15 hours ago, Plavna

I tried that before and when I hook up on the car battery, 10 starts, all fine. 

^ Yep, you found the answer yourself. It's not grinding you are hearing it's the starter struggling to turn the engine, making lots of noise because it is reaching its limit with the available voltage and amperage...

Hingley, 4/15/2022 at 9:38 AM

Very cool to see a 3rd gen with the optional clock

First thing I said to myself the second I started the video was, "Wow, he has the clock on his 3rd gen!"  :laugh:

Thanks for the answers guys. I will reply here when I get the new battery. Hope the problem will go away, if not I will check the starter motor also.

Here are some pictures :)

[image: Gq1Tsmd.jpg]

[image: OSGPWY7.jpg]

[image: vUd0rZX.jpg]

I put a new battery, so far so good. Will ride a bit more and see if the problem is solved :)

So far so good. Lot of stop and go rides, with small distances, turn off the bike, then turn on again... Only happened once and that was really short and started right up. 

Problem is back. Next thing is when Im changing oil, I will open, clean, lube and inspect starter motor.

What is your battery voltage with the bike idling and revving? You might have a charging issue, especially if you still have the stock R/R.

And it matters that you measure when the battery is 100% charged. 

17 minutes ago, jefferson

What is your battery voltage with the bike idling and revving? You might have a charging issue, especially if you still have the stock R/R.

I done that testing before and R/R is good. I forget the exact numbers but its 14.x something. When I turn of and measure the battery its 13.x something and after some time it drops to 12.7V. 

Its not the stock R/R someone changed it. Its from some Honda model but its not that stock sealed one.

Also someone installed voltmeter where the fuel tap should be on the left side so I can see the voltage when ridding. 

Its strange cuz its not that every time it will slow down while cranking when its hot. Sometimes it will start fine, sometimes it will slow down, sometimes almost to a stop then countinue and fire up.

Dun't know if starter solenoid can go crazy when its hot but doing fine rest of the time...

Sounds like you need to get that starter apart and cleaned.  Pay very close attention to the order of things and keep mindful of thrust washers that like to stick together, until they don't, and disappear.

I do this on every new-to-me-bike and they are always FULL of brush dust.  I rarely have to replace the brushes and usually just sand them a bit for a fresh surface.  Once thoroughly cleaned with electronics cleaner and the armature cleaned up, they spin up so nice and fast, even when hot.

Ok I will. Also I saw the manual today and I think I miss some washer on the starter terminal. I have 2 locking nuts, 2 insulated washers instead of 3 (need to check again) and one metal washer. Also I don't see the o ring on that terminal. 

I don't know how much is that important at all, 

US import?  Strange for someone to remove the remote reserve switch.  Do you have a low fuel light in the tachometer?

[image: P7220010.thumb.JPG.6247e589af9d77811816fdea30d1c832.JPG]

Ciao,

JZH

Given everything you've done and checked. I would fit a new Starter Relay, given it's age and the problems they can develop, it needs to be taken out of the equation, easy to just fit a new one then reassess the issue.

6 hours ago, JZH

US import?  Strange for someone to remove the remote reserve switch.  Do you have a low fuel light in the tachometer?

[image: P7220010.thumb.JPG.6247e589af9d77811816fdea30d1c832.JPG]

Ciao,

JZH

Its not the import. R/R failure is common so previous owner instaled voltmeter.

Is there any other starter motors from other Honda models that I can use, if I need to buy 2nd hand one for replacement? 

That starter motor design is very robust.  Settle down and cross that bridge if needed.

The only starter motors I've had to replace are the crappy 2 brush versions that the VF1000F/R came with.  And I replaced with used VFR (4 brush) starters.

1 hour ago, Captain 80s

That starter motor design is very robust.  Settle down and cross that bridge if needed.

The only starter motors I've had to replace are the crappy 2 brush versions that the VF1000F/R came with.  And I replaced with used VFR (4 brush) starters.

Good to know that, thanks.

Also, one thing that I hope isn't related to this problem. The famous pink connector which is near starter solenoid is slightly melted on one side, but not that much. Dunno if that can be the cause of this problem, cuz its not giving the power to the starter.

I guess somehow starter motor gets heat soaked, but I never heard that is problem on any motorcycle...

It's the abundant amount of brush dust that increases the resistance of the starter motor and gets worse with heat.

You can buy replacement wire lead / plugs for the relay and you simply must replace it at this point.  Solder or solder-seal a new one in.  I've been doing this a lot lately and is a common issue on these bikes.

20 minutes ago, Captain 80s

It's the abundant amount of brush dust that increases the resistance of the starter motor and gets worse with heat.

You can buy replacement wire lead / plugs for the relay and you simply must replace it at this point.  Solder or solder-seal a new one in.  I've been doing this a lot lately and is a common issue on these bikes.

I will probably sort that plug the last. Problem is that I don't have electric or soldering knowledge and also I don't have these small OEM parts in my country so I need to order it from abroad on which I need to pay shipping + tax +customs... 

Should I sandpaper the commutator or is it enough to clean it with contact cleaner, rug and tootbrush? Someone say you can sandpaper it, someone you shouldn't.

Sand the brushes a little.

I know this sounds weird, but get yourself an old school red rubber eraser for the armature.  Anybody that raced slot cars knows what I'm talking about.

Look into solder seal wire connectors and a good heat gun if you're solder skills are lacking.  You can source the plug kits off ebay.

I have some 30W soldering iron that I bought for the electronic, don't know if thats enough. 

I will post the pictures or write after I open the starter and see what is inside :)

I got it out :) Tomorrow I will countinue. 

I guess these lines are aligment marks. Is this properly aligned?
[image: nakY78M.jpg]

They are not 100% lined but I guess this is fine?

That exit gear shaft is in the motor oil right? Should I grease it when Im putting it back or not?

That little bit off is fine. 

No need to grease the spline, just lube up the o-ring with a touch of oil when reinstalling.

1 hour ago, Captain 80s

That little bit off is fine. 

No need to grease the spline, just lube up the o-ring with a touch of oil when reinstalling.

Ok here are some insights :)
One washer is chipped, don't know how much is that important but just to notice.

Inside, some black dust, not that much but there is. 

[image: l9ZY6tQ.jpg]

--

Now these brushes (movable parts) are 10mm in height and 5mm wide. I measured only the part that is sticking out, not the inside. I read in manual that minimum is 6,5mm but don't know what to measure.

[image: wPFKYsO.jpg]

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Now this is a commutator, I see that the copper part is black, can I sandpaper this with a fine sandpaper? 

[image: A7tge9w.jpg]
 

Also you said something about red rubber eraser, so that is for that fatter aluminium part right?

As long as the brushes have to get pushed back a fair amount when re-installing, they are likely fine.

The Red Eraser is to clean up where the brushes run.  At least that's what I use, non-destructive and polishes it up.  Finish with some electronics cleaner.

Yeah, that doesn't look too bad in there.  Still worth doing.  There will be a fair amount that gets washed out around the magnets in the body too.

Wait...  is that just a 2 brush starter?  Or are the other two on the body still.

Well I can see only two brushes on the holder. 

https://www.wemoto.com/bikes/honda/vfr_750_fl__rc36/90/picture/starter_motor_carbon_brush_and_holder

Too bad there isnt full presoldered repair kit, so I can just put it in and thats it. If I order this part above, don't know if I need to order brushes separately, and the terminal also...

I suspect that brushes are worn. I will try to clean but I don't have high hopes.

If that doesn't help, the fix will probably wait another season.

Maybe this will work

https://www.msjoker.rs/prodavnica/rezervni-delovi/skuteri/starteri/delovi-startera/cetkice-anlasera-sa-nosacem-hondayamahasuzukikawasaki-125-750cc/

I hope this holder is universal shape?

Update: Brushes are pushed by the commutator so I guess its fine. 

In the process, I somehow lost one O ring and cant find it...

This is just stressfull...

Everything set, started fine, now I will let it to get some heat and see if that did anything. 

Thanks for you help I will reply if the problem is solved or not.

Tested it without fairings, let it turn the fans, drive it, let it idle...  It looks like it cranks a bit faster, so far not draging when its hot but will check when I get the fairing on. Maybe with fairings there is more heat down below. Its a bit more noisy when starting hot but so far no draging. 

In any case, it's good preventative maintenence...   if you can keep track of all the parts.

Sounds like some initial good news tho.

Yeah at least I learned something new to do and if I need to do it again, it will be faster and easier to do. 

I will ride and see.  If the problem persists, I will go with new brushes, then solenoid. I would change the cables too over time, but can't find new battery/starter cables for this bike.