Starter clutch acting up only when hot

Today I got the 750 started and drove around the block to get a feel for what it likes to do. After 5 minutes of riding around the block between 5 and 6k rpm I stopped and shut it off.

I came inside used the restroom, went outside and it would not start, the funky thing is that I could hear the starter clutch making an ugly grinding noise.

PO mentioned this issue came up only when the engine as hot. What could be causing the starter clutch to slip/grind ONLY when hot?

 

You can only hope you have the wrong oil in there......

 

Indeed.

Dragon Warrior, I am disappointed.

One would hope that you'd changed the oil already???

I wouldn't ride a "new to me" bike more than 20 FEET before I changed the oil. NO way of knowing how old it is, what oil it is, etc. Depending on the condition of the bike, in a lot of cases you don't even want to start the motor with whatever's in there.

How many miles on this one?

Betcha PO was running car oil or a synthetic, or both.

Get back on your game and get the oil changed pronto. You know what to use.

 

I changed the oil and is the right kind

 

OK, you've redeemed yourself. My apologies.

It still doesn't mean it's for sure the starter clutch.

If, for any number of possible reasons, the STARTER isn't spinning fast enough, it won't cause the starter clutch to fully "engage." Engage is in quotes because it never really engages, more like "binds/grabs ahold" which truly is a silly design. But for it to work, the starter has to be spinning with authority.

Could be the starter itself, a wiring or even solenoid issue, many possibilities.

And you want to eliminate them all before deciding to split the cases to go after the starter clutch.

 

FWIW,,

Another member on the list has the same issue with his 750 seca......brought it to the carb clinic, and with the correct oil, correct clearances, correct carbs, balanced, etc........ it sounds like trying to start a virago. Eventually it would start, but sounds awful. A replacement starter seemed to partially correct it, but not eliminate it totally.

NEXT-- I have a 750 seca, It does the SAME thing.........when cold, starts right up. when hot, grinds, etc......a la Virago. Same thing as above, correct oil, etc..... I have NOT swapped starters yet.

But it does get me thinking more about the possibility of a starter sprag issue inside the cases.

Is there anyway to service those without having to split the cases?

Dave F

 

NO.

Somebody has tried to perpetuate a myth that it can be; but the truth is, it's not possible. The is no way to turn the clutch around to get at the screws that hold it together. You can get it free, and SEE it from the back, but that's it. Anybody that tells you different hasn't actually done it.

Unless you do what Wiz did and knock a hole in the crankcase above the clutch, and turn it into a "hatch." But unless you actually want to cut into the crankcase, no.

"A replacement starter seemed to partially correct it, but not eliminate it totally." Sounds to me like the replacement starter could also be a bit "soggy" unless it was brand-new or freshly rebuilt. Remember there are also other things that can cause a starter to be wimpy; like an original solenoid (mechanical) that makes contact but doesn't really flow full current to the starter. If the solenoid contacts are pitted/dirty you can swap starters all day and every one of them will appear to be weak. (Or make you think your starter clutch is bad.)

My '81 550 used to do the "grinding rocks" thing intermittently until I replaced the original solenoid with a nice new solid-state one.

I'm not saying that starter clutches don't fail; they do. The housing cracks at the roller tracks. But it is relatively rare and there are many other possibilities to be eliminated first.

 

That's what I said, too.

The 750 that came to the clinic was the ONLY one I've ever seen that was doing it to that extent, have seen the intermittent ones now and then. NONE of the other xj's that I have, or have had, have ever done that.

The replacement starter was a used one from another bike that the fellow has.......

I have not swapped starters around on MY 750 yet, so no insight on that one.

I didn't think it's possible to get in there, but I know some have said otherwise............that's why I decided to ask.

Hey, Fitz.......sending you a pm, too.--

dave F

 

The first thing I did when I got the bike was to change oil and spark plugs. Once I got it started, made sure that there is a fresh battery, fully charged, and monitored voltage as bike tries to start.

What puzzled me is that it will not grind when cold. I can turn the starter all day long and it won't do it. Yesterday was the first time that the engine got up to running temp and truly warm. That is when this hiccup appeared.

I know this is a process of elimintation so I will try to work on all of them one variable at a time to sort it out. Now I have 4 spare starters (don't ask how that happened) to swap or just get fresh brushes and go from there.

Thanks for the help. The to-do list is long before I think about actually going somewhere on this bike but it will get done.

 

SOLENOID. Swap or replace the solenoid. It has giant "points" in there, they get carboned up and burnt and pitted just like any other points.

Then start playing "starter roulette."

 

I do have a couple of those to swap we'll see how far I get this time around.

 

if you cross the two big terminals of the solenoid with a screwdriver and the problem is still there you can move on to the next possibility

 

When the S Clutch goes bad cracks appear from where the rollers are housed to the outside. Now we all know what happens to metal when it gets hot!!!! There is very little tolerance on the taper, to start with, a bit of expansion is all it needs.

 

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