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Power to starter

Drummer4242

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I have a 1991 Honda CB750 Nighthawk. I can get the starter relay to click but nothing else. According to my Clymer manual, I checked continuity from ICM plug's green wire to engine ground & got continuity. The next step was to check between the green wire & the black connector for power. There is no black connector or black wire at that end of the harness. I had trouble with the starter awhile back and occasionally had to tap it with a small ball peen hammer. Is the starter my best bet or how do I actually check for power on the ICM plug?
 
'91 Nighthawk starter

I have a 1991 Honda CB750 Nighthawk. I can get the starter relay to click but nothing else. According to my Clymer manual, I checked continuity from ICM plug's green wire to engine ground & got continuity. The next step was to check between the green wire & the black connector for power. There is no black connector or black wire at that end of the harness. I had trouble with the starter awhile back and occasionally had to tap it with a small ball peen hammer. Is the starter my best bet or how do I actually check for power on the ICM plug?


I've got the same year and model, Drummer. My starting system eventually did the same as yours. Strong click from solenoid, juice @ starter motor terminal, but nothing else. Pulled the starter off and opened it up (pretty basic). The carbon brushes in the starter motor were completely worn. One of them no longer reached the rotor/commutator. Went to auto parts store and got replacement brushes for (almost any) 12v car starter - about $7.00. They're soft. You can easily cut them down to size w/a hacksaw, and then finish making your "brush extensions" w/some 80-100 grit sandpaper. Leave the old brush stubs and springs in place. Just add a new chunk of what you shaped (about 1/2 inch long) into each slot and reassemble the starter. Test it w/the bike battery and some coated wire before you reinstall. I did that 11k miles ago and it starts every time. You'll save some bucks. Even a good used or new aftermarket starter will cost you $180-$250. All that ever wears out are the carbon brushes. Hope this helps get you up and running.
 
You can go to a well equipped Ace hardware to find small brushes that may not need cutting to size at all, and they DO sell the correct brushes for those starters without all that.

Stacking one brush on top of another stub is a little TOO budget.

The bushings and commutator sectors also wear on those, I rebuild them all day long as well as car ones too. Need a bit of grease to make the bushings last longer. I haven't bought a starter for anything in like 40 years, rebuild only just like the alternators, too easy.
 
You can go to a well equipped Ace hardware to find small brushes that may not need cutting to size at all, and they DO sell the correct brushes for those starters without all that.

Stacking one brush on top of another stub is a little TOO budget.

The bushings and commutator sectors also wear on those, I rebuild them all day long as well as car ones too. Need a bit of grease to make the bushings last longer. I haven't bought a starter for anything in like 40 years, rebuild only just like the alternators, too easy.

Can't find any brushes that fit @ Ace Hardware, amc. Neither will you even find a genuine Honda dealer that sells _parts_ for a starter motor. The motor yes, but not individual parts. I took for granted that most posters here have neither the training or equipment to braise the brush's copper connectors to the bimetal brush holder / end plate of a '91 Nighthawk starter motor.

And, although it does save money, "budget" is not the primary reason for "stacking one [self-shaped] brush on top of another stub". It also saves a bunch of TIME. No waiting for "brushes in the mail". And by leaving the original "stubs" in place, your electrical connections stay already made. The new "extensions" (hacksawed/sanded into shape in 15 min. total) are automatically connected, and can't come out or off because, w/the motor reassembled, they're held in place on all four sides, and at both ends by the springs and commutator. The bushings couldn't be hurt by a spot of grease. And, as long as it's exposed, you might as well clear the commutator slots of carbon dust w/a small screw driver (another 30 sec. or so).

Unless you're set up in a professional shop, that's the easiest, fastest, cheapest way to get the job done. The "brush extensions" starter will be just as dependable as it was when new. I think that's what the original poster was looking for. Rubber-side down, amc. ;o))
 
It will, until the extensions get short then the brush will try to twist out much earlier since not held in place by the end. You won't get life all the way until the end of your added piece, it will come out before that and depending on how tightly you held your spec making the part. Sloppy work = dies quicker. If they can't braze how well will they do that? The holder has to have a certain amount of airgap to not short the spinning rotor and usually pretty big. Tell me you can't see the cockeyed twist wear when the OEM brush does that before the end of it. Some of us did that type of mod and many many years (40?) ago. BTDT. You might get a half life there.

Time is no issue for most of these, can't see anybody driving them all day long as the only vehicle available, I did that when young and people rightly though of me as crazy then too. Even so, saying time is essential = death, how the industry gets you for 300-400% more cost, they know you gotta have it. I worked parts for many years. I NEVER attach a time element to repair, it increases the cost too much, and I repair 100% of everything I own, often repairing the broken parts again with less than $10 of cost. Methods just like that but they have to have a better outcome, that's not good enough for me.

I could be wrong though. Wouldn't be the first time.

http://www.ebay.com/itm/New-Starter...14-/281316342617?_trksid=p2352135.m2548.l4275

Even with free shipping.

Found brushes in 3 other places too but at higher prices. Mitsuba SM-13 starter.
 
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Nighthawk 750 starter (fixed NOW)...

It will, until the extensions get short then the brush will try to twist out much earlier since not held in place by the end. You won't get life all the way until the end of your added piece, it will come out before that and depending on how tightly you held your spec making the part. Sloppy work = dies quicker. If they can't braze how well will they do that? The holder has to have a certain amount of airgap to not short the spinning rotor and usually pretty big. Tell me you can't see the cockeyed twist wear when the OEM brush does that before the end of it. Some of us did that type of mod and many many years (40?) ago. BTDT. You might get a half life there.

Time is no issue for most of these, can't see anybody driving them all day long as the only vehicle available, I did that when young and people rightly though of me as crazy then too. Even so, saying time is essential = death, how the industry gets you for 300-400% more cost, they know you gotta have it. I worked parts for many years. I NEVER attach a time element to repair, it increases the cost too much, and I repair 100% of everything I own, often repairing the broken parts again with less than $10 of cost. Methods just like that but they have to have a better outcome, that's not good enough for me.

I could be wrong though. Wouldn't be the first time.

http://www.ebay.com/itm/New-Starter...14-/281316342617?_trksid=p2352135.m2548.l4275

Even with free shipping.

Found brushes in 3 other places too but at higher prices. Mitsuba SM-13 starter.

"Methods just like that but they have to have a better outcome, that's not good enough for me."

The poster wasn't fixing OTHER PEOPLE'S BIKES FOR PROFIT, amc. He was looking for a way to get his own bike back on the road, asap.

He's a rider - a real enthusiast. As with all such people, riding times w/out their motorcycle is like time in jail. No such person would ever say, "Time is no issue for most of these, can't see anybody driving them all day long as the only vehicle available...", as you just said. How long has it been since you really did some miles?

Of course you're right that putting "extensions" on the starter brushes won't last nearly as long as new ones will. But, as I have already stated, I did just that w/my '91 Nighthawk 750 starter AND IT'S STILL WORKING AFTER MORE THAN 11K ADDITIONAL MILES! A real rider can/will do that, as opposed to waiting for "parts in the mail" and/or waiting for some dealer/repair shop to charge him $125/hr. to work on a $200 starter motor... when they get to it.

This past week I took mine out again (a quick and easy task, as you know?) and removed the outside cap to check the brush extensions. You're right again (except in wear time). They are worn to the point where they may soon twist out of the holders. BUT THAT'S ELEVEN THOUSAND+ MILES, amc! Hardly a 'stopgap' repair. And now I'm going to REPLACE THE EXTENSIONS, for my next 11k miles. Being in the business yourself, more or less, I'm sure you realise that the typical owner puts less than 5-6000 miles on a bike before he sells it or consigns it to a corner of his garage or shed. With that in mind, 11k miles on a repair is a lifetime.

You know your business, amc. But it's obvious you no longer ride much yourself, if you ever did. Rubber-side down my friend, in case you ever do.
 
You and I come from different worlds, I do not fix things just to get 11K miles. That IS a stopgap repair in my world. If I had a starter out at all and apart it would go back in to last at least as long as the OEM one did and it better be longer. You can relegate yourself to the position of 'typical owner' if you want.

I don't and never did fix bikes for profit, that's what I did to stop paying those rates. I loathe dealerships of any ilk and never let anyone other than me touch any car or bike I've had, the incompetence is everywhere now. My being smarter than a Kawasaki dealer in '73 set me on my path toward dealer hate, and since then I have only walked away from them including with cars. I refuse all new car warranties and have since forever. It's proven to be easier just fixing the cars myself, the couple of times I let a dealer touch one was only to great disappointments.

I have well over 300K miles on bikes, I quit counting long ago.

You're now replacing the extensions again for another 11K??? Why? You could have had a new set of brushes in your hands by now, I even gave you a link for them.


'I'm sure you realise that the typical owner puts less than 5-6000 miles on a bike before he sells it or consigns it to a corner of his garage or shed.'


Of course he does with repairs like that, everything he's rigged is falling apart too quick again. Your catch 22 and self-fulfilling. Me, I wear them dead out. At least 30+K each, by then the tensioners are falling apart here in the Texas heat. My 550F has 35K right now.
 
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X2. You could teach a 6th grader to do it, I was doing it that young on a '66 Honda CB160.

I rebuilt my first bike clutch in 20 degree weather because I wanted to ride so bad. '67 Yamaha YM-1 305, the early one with the weird primary clutch that went on the end of the crankshaft itself. That first clutch rebuild lasted for many years after I did it too. That clutch was more like an ATX clutchpack, it preloaded at assembly rather than having the outer plate that you tighten down against clutch springs like most bike clutches do. I had to get Dad to push all the guts down into the shell while I popped the snap ring on that held it all together.

What I had same color and all.

https://www.youtube.com/watch?v=ghepMWOfcYM
 
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POSSIBLE CAUSE AND CURE FOR HOT STARTING PROBLEMS
My 1991 Nighthawk CB750 would start fine when cold, but after the engine was hot (about a 30 minute ride), the starter would barely turn the engine over (as if the battery was dead). I did all the usual checks to confirm the battery was good and fully charged, all electrical connections were clean, and the starter relay worked. Then I removed the starter, while it was still hot, and noticed the starter gear was very hard to turn by hand. When the starter is cold, it turns much easier. So I took the starter motor apart to check everything out. The brushes were good, the reduction gears properly lubed, the bearings were good, rotor/commutator checked with ohm-meter and were also good, so I put it back together and noticed that as I was tightening the 2 long bolts that hold the starter motor together that the starter became very difficult to turn by hand again. This made me think the rotor shims were somehow too thick and causing the rotor to bind up on the bearings; I ended up removing (qty 1 of the .008" shims on the gear end, and qty 2 of the .008" shims on the brush end, and this combination allowed me to bolt the starter motor back together (at full 108 in-lb torque) with no increased turning resistance. It took several tries at removing shims and re-torqueing the starter bolts to get a combination that worked without being too loose. After I re-installed the starter, I have had no more problems with hot starts. I can hit the red kill switch, with a hot motor, and the starter cranks just as strong, and with no slowing down, just like it does when it's cold.

CONCLUSION
Even though I purchased the bike used, I'm pretty sure the starter had never been out of the bike, so the rotor shim thickness (on each end) was probably the same as it was when it left the factory. My theory is that over the years the phenolic resin / plastic / or whatever it's called that isolates the bearings from the rotor core swells, and makes the rotor shims too tight. This seems opposite to the way things normally wear, as I would expect you'd need to add rotor shims to make up for axial play in worn bearings. Maybe that's how things wear on bikes that are used regularly, but in my case, the bike has about 48,000 miles and had sat for 10 years (unused) before I got it. I bet a lot of other Nighthawk owners have bikes that sat for years at some point in their lives, so perhaps removing rotor shims could be the cure for other's hot starting issues....
 
Good work.

At 48K miles I'd be willing to bet the starter has been out and apart before as the starters rarely are overly tight, usually having a bit of endplay built into them, that endplay is an assembly standard they shoot for. Anything is possible though. Something to look for.............I pretty much guarantee that clearance and free spinning when I rebuild one, car or bike. Even the starter cases slightly moving around out of concentric while tightening the long screws can tend to seize some shafts up. BTDT.

FYI, phenolic plastic is used because it pretty much NEVER changes dimensions based on time or exposure to chemicals. If pressed in though a lipped phenolic part can MOVE to be too tight occasionally.

Best thing here is the quick to be thinking out of the box, and I do it religiously. NEVER accept any faulty part or assembly as right until you yourself have inspected and passed it as such. I have rebuilt so many different things that in the process of which I changed several things away from the OEM standard to have them run perfectly and forever after. OEM specs are only a starting point, once you have the skills you can change them all over the place to often do better.
 
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I agree with you on phenolic's being more dimensionally stable over a wide temperature range than other plastics, but with year's of heat cycling and exposure to oil and gas, who knows what can happen. It's also possible a PO had the starter apart and put too many shims on it.....

Regardless, there's a lot of wisdom in the experience of others; I'm glad I found this site shortly after getting a (new to me) bike, and a search of this site led me to several useful tips on this problem.
 
With previously owned stuff you learn to expect ANYTHING, even the whacky. I myself have been greatly aided by a pessimism that surpasses most, it has lead me to some of the most unusual fixes (as viewed by the rest of the world) that just make perfect sense to me and they work for years. How I've for example fixed more than one automatic transmission that was declared dead and needing rebuilding by simply adding an OEM unapproved shim or modding a part slightly to then have it last many more years at a cost of nil to me.

Money is not where you trip over it, rather where you think a thing out further than most do to make it work again and for a long time after. The people who do repair for a living look at things in a certain light and usually not in your best interest, rather to cost you more to support their shop. There are a thousand ways to circumvent most of that if one just works his brain a bit beyond the norms of 'I need a new part'...........exactly what you ended up doing here.
 
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