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Grinding sound when cranking hot, bad battery?


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Cleaned these bolts, wires, battery cables.

 

Also this is what I was talking about. Starter relay plug is bit melted, inside is looking fine and on the side is a melt. I isolated with a duct tape that part. Doubt that is the culprit but can be potential problem for something in the future.  It was like that when I bought it so it didn't spread or something in the meantime. I guess it was cuz r/r failure in the past or something else.

Ikvkbyh.jpg

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R6630wH.jpg

 

Im countinuing chasing gremlins... :D

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The main power plug is a known problem.  Same as the 3 yellow wire plug from the stator. They get dirty/corroded, the resistance/heat goes up and they melt-down.

 

That looks surprisingly "clean", but the resistance from just the connectors will do it.

 

 

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  • 3 months later...

I am selling my motorcycle, I don't know if I fixed the problem cuz Im not ridding it anymore but I found one thing in the french article with VFR750 with 500.000km!!! 

from french on gt:
– Starter  freewheel, because when it comes to restarting when very hot, the freewheel slips and no longer exceeds the torque of the starter. (well the stroller).

 

I guess that is famous starter clutch slip or is this some starter freeplay???

Here is the original on french:
 

 

– La roue libre de démarreur, car quand il s’agit de rédemarrer lorsqu’elle est très chaude, la roue libre patine et ne passe plus le couple du démarreur. (donc poussette)

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The starter clutch has rollers that are pressed onto a shaft by springs, that locks the components together. When the rpm rises the centrifugal force overcomes the springs and the rollers retract and release the shaft. The rollers and or springs do wear, but they are easy enough to replace once you have the clutch cover removed. The starter clutch on my 86 is mounted on the crank end, the three bolts allow the halves to split so the rollers etc can be replaced. I used a kit from Wemoto such as the one in the link.

 

http://www.wemoto.com.au/bikes/honda/vfr_750_fl__rc36/90/picture/starter_clutch_repair_kit/

 

IMG_2539.jpg

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Also on some models, the centre of starter-clutch cracks from outer part. Leading to some misalignment and slippage. Noise is warning sign of impending failure.

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Starter clutch can be affected by temperature changes as it changes tolerances and the heat changes the viscosity of the oil that the clutch is bathed in.

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Ok thanks. I am selling it atm but if I keep it, first I will open the case and check for crack. If there is no crack, then I will change springs and rolers aka repair kit from Wemoto. Just in case.

 

But I don't have a slipping sound like bad starter clutch its more it is stalling/slowing down then countinue then fires up. Like bad contacts/battery/brushes on motor.

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NOT another oil debate, but if you’ve put in a synthetic oil of car (automotive) type, drain & replace with motorcycle specific or diesel version conventional oil. You’re grasping straws anyway, can’t hurt to try. I cured a similar issue years back by this method, haven’t used a synth oil since!

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On 9/12/2022 at 9:37 PM, airwalk said:

NOT another oil debate, but if you’ve put in a synthetic oil of car (automotive) type, drain & replace with motorcycle specific or diesel version conventional oil. You’re grasping straws anyway, can’t hurt to try. I cured a similar issue years back by this method, haven’t used a synth oil since!

Im using semi-sint oil. Previous oil was Ipone R4000 15-50w, now is Total 10-40w. MA2 standard, motorcycle oil.

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The engine in the RC26 has about 15K miles on it.  I had the covers off to paint them and inspected the starter clutch, it had no cracks.  I run Castrol 4T conventional oil.  Every once in a while it cruches-slips-crunches.  Hit the button again and it starts perfectly.  Won't happen again for months, maybe the next year.

 

If my cover ever comes off I will do the springs and rollers just cuz.  Last engine had about 30K+, it did the exact same thing. (I went thru another motor when I changed the frame to one I had the title to)

 

It happens on some of these bikes.  And can get worse with mileage.  The more it happens, cracks start to form. 

 

But my 86 750 with 58,000 doesn't do it at all.

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My 86 starter made some dreadful sounds while I was sorting out carburetion issues. There was a lot of work for the starter motor, and I think this was draining the battery and occasionally just not spinning smoothly to keep the clutch engaged. With a decently running engine (starting easily) I never heard the same noises, but decided to replace the rollers and springs in any case. The rollers looked OK but the springs were quite a bit shorter than the replacements. This was with 105,000km. Fortunately the clutch body itself had no cracks and looked perfect. 

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6 minutes ago, Terry said:

My 86 starter made some dreadful sounds while I was sorting out carburetion issues. There was a lot of work for the starter motor, and I think this was draining the battery and occasionally just not spinning smoothly to keep the clutch engaged. With a decently running engine (starting easily) I never heard the same noises, but decided to replace the rollers and springs in any case. The rollers looked OK but the springs were quite a bit shorter than the replacements. This was with 105,000km. Fortunately the clutch body itself had no cracks and looked perfect. 

 

Yeah when the battery starts to get drained from a a lot of cranking (or is just plain old) it can be the difference.  Needs to spin up fast to keep the clutch engaged.   Also I think I mentioned it, but servicing the starter motor (which I think you did) is a good move too.  That can be the difference right there too.

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15 hours ago, Captain 80s said:

 

Yeah when the battery starts to get drained from a a lot of cranking (or is just plain old) it can be the difference.  Needs to spin up fast to keep the clutch engaged.   Also I think I mentioned it, but servicing the starter motor (which I think you did) is a good move too.  That can be the difference right there too.

Yeah this is what I wanted to do next year, new holding with brushes. Battery was new so that isn't a problem. Maybe the battery cables but I don't even know where I can find those new. Checked the grounds etc, all fine.

Didn't try to check starter relay but I guess it will fail every time not just when really hot. So I still suspect on starter motor then starter clutch parts.

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If you cleaned out the brush dust, sanded them a bit and cleaned the armature, that's usually all that is needed unless the brushes are TOAST.  I have never had to replace the starter brushes on any of my bikes I've had the starter apart on (which is about a dozen V4s).

 

You would have to make a set of your own cables or find some generic pre-made items in the right lengths and fittings. Rarely is that the issue unless the bike has spent time as a boat anchor, but I have swapped out some crispy looking ones just cuz, even tho I wasn't having issues.

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  • 2 weeks later...

Also

 

Ok, what I need to line up after I do the springs and rollers change or even whole clutch? Can I make some mistake? What are the markings on the clutch for?
Or can I just take if off and replace and put it back on the bike?

What about that little pin that I should took from old clutch and put on the new one? More explanation please, or maybe pictures.

 

Can the loose golden screws result this symptom? (only hot start issue)?

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