no charge until engine is warm ?


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tubehead
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no charge until engine is warm ?

Post by tubehead »

I just replaced the alternator seal and bearings.The brushes look new .There was an extra washer in there not shown on the exploded view in the parts manual so I guess someone has shimmed the spring at some stage.The bike has always had no charge on start up but as soon as it warms up it it goes to 13.85 @ 3000rpm and charges normally until the next cold start up.Is this indicating a need for a new alternator clutch ?
They did not look overly worn.

daves79x
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Re: no charge until engine is warm ?

Post by daves79x »

Probably indicates that your battery is somewhat drained and taking a pretty good charge initially, thus not showing much voltage build-up for a while, or the regulator is not up to snuff. Also, don't exactly trust the Honda voltmeter.

Dave

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Re: no charge until engine is warm ?

Post by tubehead »

The battery (AGM) is a little down 12.05 volts at rest but the bike was on a ship for 10 weeks and I have not taken a long ride yet or fully charged it.
The volt meter on the dash exactly duplicates my multimeter which shows 11 .95 with nothing going in even at 3000rpm on start up and then it is like the alternator clutch finally catches and it jumps up to a decent charging rate once the engine is warmed up.
Considering the low battery it should be charging full rate at anything above idle with a normal alternator but was wondering if this is just a cbx thing?
Not fully conversant with electrical matters but have never seen this before.

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Re: no charge until engine is warm ?

Post by Rick Pope »

Most people think the gauge is showing charge. In fact, it is showing how much electricity is in the system, or volts. To see if you are charging, you need to measure amperage.

Imagine that your battery is a glass of water. It takes some of that water to start the engine. It takes a little while for the alternator to re-fill the glass. When the glass is down a bit, you might show 11 volts. but after a few minutes charging, it's back up to 13 volts.
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Jeff Bennetts
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Re: no charge until engine is warm ?

Post by Jeff Bennetts »

What kind of oil are you using, synthetic and synthenic blends will cause the alt clutches to slip until the motor warms up. :o

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Re: no charge until engine is warm ?

Post by Larry Zimmer »

G'morning, mate. Just a comment regarding your charging thing: My '82 has operated in that manner for years. Just ride away. Typically, within the first 5 miles, the needle will rise steadily, or, 'jump' from 11.5 to 13+. All is well after that. If it doesn't, then, you have a problem either with the battery or the charging system. As a note, the 'resting' battery voltage should be 12.5 - 12.7 with no load/ignition off. If not, either the state of charge is low; or, the battery may be hurting.

And, yes, as Dave mentioned, don't trust the Honda meter for accuracy. It is only a 'reference' instrument. Aside from inherent questionable accuracy, it is measuring voltage after passing through several connectors which may have influence depending upon state of corrosion of the connectors.
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ajs350
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Re: no charge until engine is warm ?

Post by ajs350 »

tubehead wrote:I just replaced the alternator seal and bearings.The brushes look new .There was an extra washer in there not shown on the exploded view in the parts manual so I guess someone has shimmed the spring at some stage.The bike has always had no charge on start up but as soon as it warms up it it goes to 13.85 @ 3000rpm and charges normally until the next cold start up.Is this indicating a need for a new alternator clutch ?
They did not look overly worn.
You mention the extra washer suggesting the spring may have lost some of its lenth and ability to put pressure on the plates. The free length of the spring should be 1 7/32. If it's any shorter perhaps a new spring would help.
Ross

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Re: no charge until engine is warm ?

Post by daves79x »

I should add that if your battery is that low, you should charge it manually instead of letting the bike's system do all that work. It will charge it harder than it should be.

If slipping clutches were your problem, you'd have a heckuva racket going on there. You should, however, check the spring's length as Ross said - 30mm for you metric types. Anything under that and you should shim the spring more, or get a new spring, which is NLA from Honda.

Dave

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Re: no charge until engine is warm ?

Post by EMS »

I really don't think the clutch is slipping. You would probably hear a chirping noise, if this was the case. The slipper clutch was supposed to protect the alternator from engine rpm peaks, when blipping the throttle. Although the condition of the spring is a factor, I don't think it slips in your case, when you hold a steady rpm. Rick has the situation described very well and I think you would see a difference, when you start out with a fully charged battery. You can put a load on the alternator by holding the brakes and switching on a turn signal. Then hold the rpm at around 2,500 to 3,000 rpm and see if you hear a sound from the alternator housing.

tubehead
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Re: no charge until engine is warm ?

Post by tubehead »

I will fully charge the battery and all should be well.I have had 2 previous cbx's and never noticed this but then again I never had a flat battery.
The main reason for taking it apart in the first place was the the annoying leaks that landed on the left header collector overnight and smoked until it burnt off.
It was actually the large O ring which was not available in Australia so I used a smidge of sealer and it is now leak free.
The bigger bearing seal was also letting a tiny amount of oil over to the dry side which leaked out of the wiring grommet.
The bearings felt ok but for $15 I replaced them any while I was there.


Thanks for all the help

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Re: no charge until engine is warm ?

Post by daves79x »

You might check that square o-ring again. It is not square - it's rectangular in cross-section. You install it so the wider profile gets squeezed. The narrow profile won't fill the groove in the cover and it's not supposed to. Incorrect installation has resulted in a lot of leaks. Installed correctly, I've never seen one leak.

Dave

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