I have a '90 CBR 1000 that has always been a bit reluctant to start. Since spring I have replaced the battery, the plugs, the plug wires - I have removed and cleaned the carbs, synced the carbs, and adjusted the valves. All my effort has made the bike nomore dependable. The bike runs fine once it has started. A little starter fluid willalways do the trick, as will a bump start while coasting down a hill (sure would hate to push that beast up to the top for a second try!). Hot or cold dosen't seem to matter. Now in my opinion the starter has always turned a bit slow and seems to be getting slower (possibly too slow to start the bike?). Does this seem like a good guess and is there some way to isolate this as the cause of the problem besides buying a new one and giving it a try? Voltage at the battery is 12.5 and drops to 11.4 when the starter is turning if that means anything to one more experienced.

Thanks in advance for you advise.

 

It sounds like your Starter Clutch and Alternator Damper are screwed.

 

Thanks for the fast reply. I am curious what makes you think it is the starter clutch (splitting the case makes paying for a starter sound like a cakewalk). The motor always turns albeit slowly. Turns fast with no plugs. What does this clutch do and how does it work - I can't make heads nor tails from the shop manual schematics and what part would fail and slow the way the starter turns (bearings?)

By the way I pulled the starter and the brushes are all well within spec but turning the assembled starter was and is much more difficult than I would imagine an electric motor with no transmission. Is this normal? TonightI will check for voltage leaks within the motor.

 

My experience with starters is totally automotive, so take what is said here with a grain of salt. But - starter motors are harder to spin by hand than one would expect. That said, if your starter motor is reallyhard to spin by hand you may have bad bearings which could allow the armature to drag on its field windings. It can happen - see the attached picture of what I found when the alternator cover was pulled on my '91 1K. If you haven't checked bearings you might do so.

Other than a dragging armature slow turning is usually caused by poor electrical connections. You've checked the brushes and say they are good. Your battey has been replaced, so we can assume you cleaned and made sure the connections there were tight. Did you check the ground connection from your battery to the bike? Then check the wiring from your battery to the starter to be sure there are no poor connections, broken wires, shorts, etc. If all that checks out - bearings, wiring, etc. - you should have the armature and fields checked out. If you have a good enough multimeter and the specs you could do it yourself, otherwise a trip to a good mechanic is in order.

Like you, I'm not sure a bad starter clutch would cause slow starter opperation, but as said before, I'm no expert in that department of the CBR1000F. If your starter checks out good then that's an option to explore.

[IMG]local://upfiles/1929/83F5BFFE38764C2897A6BCC376F5246E.jpg[/IMG]

 

Yes a bad starter clutch and alternator damper slows the starter down.

The usual symptom is starter starts out normal for 1st few sec than slows down to a crawl, but will bump start perfectly.

Of course you need to go to the effort of ruling out battery, R/R, contacts etc 1st.

I have never figured out why the CBR acts the way it does with the starter

 

Another test to check this would be to put an battery supply to the starter directly and see if the problem persists.

 

Dang! I missed that step. Always was the first step after removing a starter and the last after rebuilding before putting it back in.

 

Hey!

It seems, that i have same symptoms[:@]

is it possible to remove the starter motor without taking of the whole engine?
I mean how much i have to take the bike apart to get the starter out with cluch and to chek it?

 

First, the problem (on my bike anyway)is apparently the starter clutch or alternater damper, both of which ride on the alternator shaft. The starter motor itself does not have to be removed (that would be too easy). I have notpreformedthe surgery yet, but according to the manual, the motor needs to be pulled from the bike and the case split to do the job. Now I recieved an email from another member who went the "split the case" route to change the starter clutch, put his bike back together only to find the same symptoms. The problem was actually the damper. Not thrilled with the idea of pulling his freshly installed motor again he found that if you lay the bike on its side you can do the job with the motor in the bike. Evidently the reason for splitting the case is that there is a chain that goes over this same spindle and if you try to change it with the bike upright the chain just falls into the case never to be seen again. Laying the bike down keeps this from happening. One could only know this if one did the repair by the book the first time and was not getting paid by the hour to do it again. I am going to go this route later (the worst that can happen is I have to pull the engine to retrieve the chain). In the mean time I will continue to park the bike with its nose pointing down hill. If you beat me to the repair let me know how it goes! - Good luck!

 

well i took off the starter and disassambled it, cleaned and put together again, sama problem - so the starter is ok.
Problem probably lies in starter clutch witch doesent lock properly and so the clutch is slipping. I checked it by removing cylinder head cover and trying to run the engine with starter motor. It was kinda step behind. so it was a sign of slipping clutch.

I have heard that the clutch can be repleaced with the engine in frame. And it is done by alternator hole - one must be taken of of course. I have tryed to do it today, but stuck with some time problems so i have to put it together again and do it again next weekend and use the "mägistarter" ( downhill starter )

well trying to keep you up with what is happening with my bikes starting clutch