Greetings

I posted earlier about problems with my 1990 CBR1000FL, that will not start on the starter, but bump-starts fine and runs fine always once started.

When I hit the starter, the engine turns over, but with a very labored sound, very slow. At times it will spin up to normal speed, and then the engine will start. But this is rare.

I have used a car battery instead of the M/C battery, and the same thing happens.

To date I have replaced the starter motor, and put a new starter clutch in.

I have measured some voltages at various points, and have found some low volts.

I have connected a lead directly to the starter motor mount bolt as a -ve.

I am using the +ve starter motor lead that goes to the solenoid, but have disconnected it from the solenoid.

So effectively, I have the starter directly connected to two power leads.

I connect my car battery, via a set of car jumper leads, to these two starter motor leads.

With the car engine running, not connected to the M/C starter, the battery reads 14.4 volts at the car battery.

When I connect the car battery to the starter motor leads and crank the starter, the volts at the car battery fall to 12.2. Same volts at the end of the jumper leads.

When I connect the car battery to the starter motor leads (via the jumper leads) and crank the starter, the volts measured at the ends of the two leads from the starter motor read 8.8 volts.

When I connect the car battery to the starter motor leads (via the jumper leads) and crank the starter, the volts measured at the -ve starter motor lead and the +ve starter motor terminal read 8.2 volts.

Obviously these 8.x voltages are not enough to crank the starter at a decent speed.

There is plenty of current being pulled ( unmeasured ) as the starter leads get hot pretty fast.

What could be causing this voltage drop? A slipping starter clutch would not. Could I have two dud starter motors?

Any suggestions very gratefully accepted.

Thanks

 

have you checked the started solenoid

 

According to the Honda Service Manual for the 90-91 CBR1000F starter motor turns engine slowly is caused by: a) weak battery, which you have eliminated b) excessive resistancee in circuit, which you seem to have eliminated or c) binding in starter motor, a distant possibility.

A question: when going from your car battery to the starter did you connect directly to the starter, or did you connect to the bike's positive battery lead? It sounds like you connected to the positive solenoid terminal, bypassing the bike's wiring harness. If that is so, you have eliminated all but the solenoid and starter as your problem.

I am not familiar with the starter on your bike (or mine, for that matter), but the solenoid in automotive applications is frequently the culprit in a malfunctioning starter. Bypass the solenoid completely if you can, and see if the starter then spins normally. If it doesn't you have probably got a defective starter.

 

Alright, I've got it figured out finally. I had the thing making a godawful noise when trying to turn the motor over and once in a while the motor would actually turn and fire up. [/align] [/align] I don't fix problems by throwing parts at them, but I'm in a unique situation that made it possible. I have an extra engine that I will be putting in a go kart later this year and still had to collect the starter, wiring harness, everything down to the alternator shaft that the starter gear engages. [/align] [/align] So I went through and one by one replaced the whole starter system using the parts that proved good on the extra motor. Well, I had someone tell me it was the starter clutch, which would have made sense, but it turned out not to be. I originally put in a used one to conserve money, but when the problem shortly turned up again, I put in a brand new one, having found out it was only about $30 new, and wanted to rule out a faulty part. Same thing, so next was the battery, then the starter itself. I hotwired the starter in the bike directy to my truck taking the entire wiring harness, solenoid, and battery out of the picture and had it do the same thing. So I knew it had to be mechanical and it had me scratching my head. (Oh and for reference, you will have some people tell you that you have to drop the engine and crack the case to do the starter clutch. They are on crack. The starter clutch slips onto the alternator shaft which comes right out the side. I have had it apart a couple times now. See link below.)[/align] [/align] Then I inspected the inards a little closer. If you look at the diagram from the shop of the components that slip on the shaft, there is a part that looks solid marked "damper" attached to the gear that runs down the camshaft. When removing the alternator shaft, it is easiest to just leave that whole peice in the bike, since it's kind of hard to get out and just sits idly while looking at the shaft/starter clutch. (See this page, part #5 for visual http://www.ronayers.com/fiche/200_03...mp;parent=5440 )[/align] [/align] I went ahead and took out that damper and behind it, the bearing that the whole alternator shaft rides on was completely shredded. In addition, the noise that was sounding like a slipping clutch was actually the damper. When you turn it over, it dissassembles and is like a tiny little clutch pack in the traditional sense. It never made sense to me why the starter clutch would sqeaul, because it's a mechanical bind. It doesn't really slip, it either works (spins freely one direction, locks up the other) or it doesn't, and when I took it out it was doing what it was supposed to be doing. [/align] [/align] So the bearing was causing the resistence and the damper was sqealing while slipping. And for reference, spark plug in or out, there was not any noticable difference in how hard it was to turn the motor. It would have been impossible to diagnose anything that way. [/align] [/align] That's all. Bearing $20, Damper, though it probably won't even need to be replaced runs about $100 new, though I just got the whole shaft assembly used for the extra engine for $150 off ebay. [/align] [/align] Hope that helps. Email if you want some more explanation! [/align]

 

hi im just about to start stripping the starter clutch on a cbr1000 fl 1990 from what you have said this seems pretty easy but according to the manual doesnt seem so when stripping the starter clutch do i have to remove the tank and carbs to get to the inspection cover to remove the retaining nut on the end of the shaft and how do i disengage the drive chain any help would be appreciated and do i have to drop the engine and crack open the crankcases like the manual says?

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