Topic: Dying starter finally crapped out... what am I in for?

[grumpy]

I'm trying to figure out how much time I'm gonna need...

Getting a rebuilt starter... on the way.
I know the tensioner has to come off. Already got a replacement gasket.
Can it be done w/out pulling the carbs? I know it'll be easier w/ the carbs & tank out of the way but that's another hour.

Are any of the gears gonna come out w/ the starer (and cause me to do a lot of cursing when I try to reassemble the whole mess)?

What am I in for?

[Duke McDukiedook]

If you are pulling it out on your own you might as well check to see if you can change the brushes, that might be the only problem.

[Frankenkit]

Hey there, I don't have the same model you do, but I'm just popping in asking how you know for sure if it's your starter motor?  Is there any chance it could be something easier (cheaper) like the starter solenoid?

I rebuilt my 650's starter, and for all intents and purposes, the pictures make them look very, very similar... so I'm going from there.
You might want to get a rebuild kit ahead of time.  I think it just consists of a pair of brushes and the rubber band seals that go into the grooves in the caps.  If you can buy the bronze bearings, do it.

I set out my work desk with some work towels and engineers paper, so any tiny parts that fell out would be very visible.  Fortunately, the only parts that want to fall out are the little (bearings?) thin bronze washers.

Before you open anything up, take a small sharp object and make a  couple lines going from the central cylindrical core to the end caps so you can be positive you've lined everything up exactly the way you started.

You'll want to use a little PB blaster on the three really long phillips head bolts that hold the top and bottom ends on.  Those buggers are in there TIGHT.  If all else fails, you can possibly do what I did and use a vice grips near the bottom and put some pressure on them counter clockwise until they break loose, then they spin right out.

now bear with me, I haven't done this in quite awhile. I believe you can just take the bottom cap off (the one that doesn't have the turning component with teeth [the armature]) and you'll see where the brushes attach, etc.  Those may be worn beyond use, and a large amount of your problem. Replace them and use electrical contact cleaner to get some of the carbon etc out of the surfaces.  Dans MC has great help here.  I used a soft toothbrush to clean carbon out of the armature segments.

I'm not sure about 750 anatomy but on the 650 I didn't have to remove carbs or tensioner.

Hope that helps... unless you mean your starter clutch, in which case someone else will have to help you out.

Also fwiw, consult your repair manual to make sure that a) everything measures out to tolerance and b) I'm actually giving you the right directions.  Also fwiw, try turning it by hand and seeing if it feels like things are dragging inside.  It might be that it's grounding out on the inside.

[Gordon]

I'm with Kit.  Are you positive it's the starter motor itself that is causing the problem?  Seems to me the solenoids go out more often than the starters on these bikes.  A corroded connection inside the solenoid can cause problems that would make it feel like the motor is going out.

[grumpy]

Actually I was thinking of changing out the solenoid too.
They are almost 40yrs old, after all.   God knows some of my 40yr old parts are pretty burned out.

OK - this is what it does; tell me what you think...

Up until today, when the bike was hot, I'd hit the starter switch and it would make a noise like the starter wasn't spinning up to full speed & it wouldn't engage the starter clutch.
It was pretty intermittent - but always when it was hot - and it gradually started happening more often.
Today it did it when it was cold.

I figured: Hot = more resistance + likely dirty/worn brushes = less current to the starter = not enough RPMs = ghaaaaaaaaaa a a a aa aaaaaaa

I wish I could get a video of it.


KIT: yeah - I bet it could be done w/out pulling the tensioner but it's tight in there.
       cool link, too. Thanks.

[Frankenkit]

make sure you're charging alright, too.  

I rebuilt my starter and that exact problem continued.  Replaced the solenoid. It continued.  Came to figure out, my bike actually stopped charging once it got hot enough, so it wouldn't have enough juice to start the bike again after awhile, hot or cold... (though when cold, the battery would gain back some voltage after having been discharged and have just enough juice to start me up again once)

Rewound rotor and stator.

Bike starts much more reliably now and charges way more reliably now... but when it's hot, it still has very slow rpms on the starter.  Seems like the bike needs 5-10 minutes (just enough time to gas up) to start up again...  but that's vastly improved over before, so I consider my problem "fixed"

[Gordon]

The easiest way to eliminate the starter motor as the problem is to jump the terminals on top of the solenoid with a screwdriver.  If the starter spins away happily then it's not the starter that's the problem. 

[grumpy]

I charging OK - I have a digital meter permanently wired to the battery. I know I'm good there (of course there's always Murphy, Heisenberg, gremlins, et al)

Man, I bet shorting that solenoid makes a hell of a spark 
Would a problem w/ the solenoid be heat-dependent?

[Frankenkit]

not necessarily, but it's a nice, easy way to check.

Your solenoid actually is supposed to connect both poles every time you hit the starter button.  What happens is, after awhile, the metal bit that is supposed to bridge the gap and deliver juice to your starter motor can eventually get fried and either permanently stick to the other side (starter doesn't stop) or not bridge the gap at all (starter doesn't start)

[Gordon]

Man, I bet shorting that solenoid makes a hell of a spark  

It does!  Just be quick and deliberate about making the connection and the sparking will be minimal.  

Like Kit said, solenoids can sometimes get stuck and either won't make the connection at all or they can even stick in the "on" position and turn the starter until the battery runs down or you disconnect it.  But they can also build up some corrosion at the point that the connection is made and allow some current through, but not all that it's supposed to, which would cause the motor to turn, but not as fast as it should.  

[KB02]

BEFORE YOU PULL OUT THE STARTER!-!-!-!-!-----

If your starter is spinning, then it might not be your starter motor. It might be the starter clutch on the back side of the rotor. I had the same issue with the starter clutch on my 750 K8. The starter would begin engaging the engine and then just spin freely. The springs wear out over time (been seeing this a lot on the boards lately - must take around 35 years for these spring to wear out - give or take 5 years) and they don't have enough tension to spin the crank.

Like Gordon said, cross your solenoid wires and see if the starter spins. If it does, your starter should be fine. Next step would be to take off the rotor cover and look for sheered teeth on any of the starter gears (#6 & 3 in the fiche). After that, get some new springs, caps and rollers (Parts #8, 9, and 19 in the fiche).



A picture from my rotor (the "rollers" can be seen just peeking out of the top plate. They are just under the little holes). The screws do not have to come out to replace them.

[grumpy]

Oi - Do I need a rotor puller to get to the starter clutch?!?

[754]

Yes you need a puller, cheap ones are available..

 Once you got the dyno cover off, its only 4 more bolts to get starter out,, should come out with carbs & canm tensioner in place..

 Are you not using a manual ?

[Frankenkit]

not speaking for grumpy necessarily, but I find that when I'm delving into some project I've never done before, I both read the manual (honda's own svc manual) and then I also ask folks here about their own experiences.  Only here will you get helpful tidbits like "Put foam under that, cuz when it pops off, it'll want to bounce off your garage floor!" or "Those tiny springs are under pressure and will try to disappear once you take off the cover" etc etc.  Layman's terms beat manualese almost every time.

[grumpy]

Yeah - I've got the Honda Srvc Manual but it's written for Honda trained mechs - or at least for guys who really know this stuff.
Kit's right it's A LOT easier when someone says "move the blue thing to the left and twist it counterclockwise a quarter turn" versus "remove the illudium space modulator from the modulator armature using tool #3453-54dfg57-475^%%$ and rotating it to 270deg"
Ya know 

So.. this rotor... how do I pull it out & where do I get the right tool?

[754]

I was just thinking, if the manual says..
 blah, blah, blah..leaving carbs and tensioner on, then it probably comes put without removing those..

 I think Z-1 carries the puller.. and I think maybe a place called pit posse.. or something like that..

 I would pull the dyno cover and let it hang or block up, re & re starter or inspect, then if you got to pull rotor later, starter swap is done..

 Why not use the kicker..

[Frankenkit]

all this has me thinking- is it this easy to get  at the 650's starter clutch?  Just curious because I've replaced everything else in the starting mechanism... and the 650s are too futuristic to have those kickers...

[grumpy]

I have been using the kicker but I like the starter.
Especially when I'm leaving for work at 6am & it's cold, dark, and drizzly. I need to get it started and get moving before the neighbors can set their sights on me.

I'll check Z1. THANKS!

[bryanj]

BE carefull of parts 4 & 5 in that picture as they frequently fall out onto the floor and can get lost (also discontinued as parts now!!)

You need alternator cover off if you want to remove starter easily as you get more wiggle space with the intermediate gear out of the way

[Terry in Australia]

I've got exactly the same issue on my F2  mate, it's not the starter clutch (I repaired that a couple of years ago and it doesn't slip) and it's not the solenoid, (I replaced the old one when I restored the bike) it's just the starter motor. Just like you, the starter motor will turn the engine over OK when the engine's cold, but when it's hot, it's like I've got a flat battery, but of course, I don't. This is the first CB750 (of the many I've owned over the last 32 years) that's done this, so it's not common, although it's quite common on Ford cars, I've replaced 2 or three over the years, with exactly the same symptoms. At one stage in a past life the bike's electrical system pretty much melted in a fire, so I'm guessing that was the cause.

Like yours, my starter motor is getting worse even when cold now, so I'll be changing it out this weekend. It's not hard to remove the carbs and airbox on my F2 (new rubbers either side) so I'll whip them off. While it might be "possible" to remove your starter motor with the carbs attached, it'll be a PITA and you'll probably lose more than an hour anyway, so my advice, for what it's worth, is to remove them first. What price un-skinned knuckles?    

[KB02]

So.. this rotor... how do I pull it out & where do I get the right tool?

I got my puller from Motion pro.

[Frankenkit]

TT once mentioned, Terry, that this could also be a sign of something in the engine itself being harder to turn- i.e. is the engine itself harder to turn over when hot?  could something be binding once heat-expanded? (or something like that?) just still running over all the possibilities. That I havent' really tried...

[jwl41085]

yea these bikes do have kickers you know 

[grumpy]

Cool - thanks Terry. Now I've got corroboration. Let me know how it goes.
figured I'd do the starter first and see how it works and do the clutch if I had to.

Thanks everybody.

[Terry in Australia]

TT once mentioned, Terry, that this could also be a sign of something in the engine itself being harder to turn- i.e. is the engine itself harder to turn over when hot?  could something be binding once heat-expanded? (or something like that?) just still running over all the possibilities. That I havent' really tried...

G'Day Kit, well the compression will come up a tad when the engine is hot of course, but that's all I hope is making the starter hard to turn over, or I will burn the baastard, ha ha!

Nah, it's all good, after being pulled out and stripped/rebuilt twice since the original resto, the engine is the best it's ever been and I'm entirely confidant that nothing is "binding", plus it's a piece of pie to kick start. But............ your point is still valid mate, because when your starter motor is clagged, it's always gonna be at it's worst when the engine is hot, and the compression is up where it should be. Cheers, Terry.

Cool - thanks Terry. Now I've got corroboration. Let me know how it goes.
figured I'd do the starter first and see how it works and do the clutch if I had to.

Thanks everybody.

No worries mate, will do. Cheers, Terry.