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Old 05-01-2009, 04:07 PM   #1
Milano911
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Default 1985 FZ750 woes...

Hi all, I recently have purchased a 1985 Yamaha fz750, blacked out. Thus I've been doing my research and also found these forums!

I bought it from a guy who says it was well maintained, he is the second owner buying it a year ago from the original guy who had a collection in some garage.

Says he got it serviced and ready to ride this season and sold it (wanted 2k, I got it for 1.5) It had 60,000 clicks and he said it ran great and ready to go. At that price why not?

Well I got it, fired it up, ran/idled great. I am still waiting for warmth to show up and also on some gear I ordered so it sat in the parkade for about 1.5 weeks. During this time I would occasionally go down and fire it up, let it idle a bit, and shut it off.

Eventually I wouldn't have enough power to start (it never fired up RIGHT away, so I must have drained the battery doing this a few times).

So the last few times I fired it up I had to get a boost from the truck because it wouldn't have enough power to start (well, it would try for a lil while then die out).

With the booster cables it fired it up almost right away. After unhooked I let it idle for awhile, my RPMS are around 800-1000 (too low?) at idle when engine is warm. After 10 minutes I killed the bike to see if I could start it up again and BAM right away. Let idle for another 5-10 minutes. Kill it, try to fire it up... bam. Third time? It wouldn't start right away and it rolled over once or twice and died... (Not enough power to start? Not enough power in battery?)

Fires right up (pretty much) after a boost. Will die after idling awhile (10 mins or so).

Is this because I've drained the battery? And it doesn't really charge up while idling? (Like in the last week I've drained the battery more than anything else, and there is only enough juice in there for a start, if I am lucky?)

I hope so, because I just bought a new battery. Hope to put it in soon. Also, this guy isn't getting back to me about some questions I had in regards to what was serviced specifically... I am not too concerned yet as the bike runs and sounds good when it is running... I think I might be anticipating riding too much and killed the battery starting it and letting it idle on and off in the last week.

Also while it idles the headlight flickers every 4 or 5 seconds, and the lights around the gauges and the headlight itself get brighter when I am rev'ing, then dimmer when it is idle.
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Old 05-01-2009, 08:00 PM   #2
mscuddy
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You need a new freeking battery! Let loose with the fifteen bucks and ride the damn thing.
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Old 05-02-2009, 08:04 AM   #3
seruzawa
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Batteries naturally create sulfate. Eventually the sulfate builds up in the bottom of the battery and shorts the plates and goodbye battery. When a battery is fully charged this sulfate builds up very slowly. When the charge is depleted the battery builds it up very quickly. Allowing the battery to sit on low charge basically ruined it. Buy a new one. Whenever you start the bike be sure the run it for a few minutes at a high enough rpm to recharge the battery fully.
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Old 05-03-2009, 03:39 PM   #4
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Starting the bike and letting it idle a few minutes is a sure way to deplete a battery. The bike never has a chance to recharge it. I see you bought a new battery; get one of the automatic trickle chargers and hook it up. The good ones come with a lead that you install permanently on the battery. The lead has a plug that you connect to the charger when you park the bike. You can use a regular charger as well if it has a 2 amp setting. The problem will go away once you start riding regularly.
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Old 05-03-2009, 05:48 PM   #5
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If you want to be sure the battery stays charged you have to start the engine then immediately roll the throttle wide open and hold it that way for 5 or 10 minutes or until you see a dull red glow around the area where the exhaust pipes exit the head.

You might want to wear earplugs.........
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Old 05-03-2009, 06:09 PM   #6
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Quote:
Originally Posted by sarnali2 View Post
If you want to be sure the battery stays charged you have to start the engine then immediately roll the throttle wide open and hold it that way for 5 or 10 minutes or until you see a dull red glow around the area where the exhaust pipes exit the head.

You might want to wear earplugs.........
You forgot to mention that you will hear the RPMs rise and fall as the engine hits the rev limiter. "This is normal."
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Last edited by sarnali2 : 05-03-2009 at 06:18 PM.
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Old 05-03-2009, 06:21 PM   #7
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Quote:
Originally Posted by Kenneth_Moore View Post
You forgot to mention that you will hear the RPMs rise and fall as the engine hits the rev limiter. "This is normal."
true, I didn't think that needed to be mentioned but you're absolutely right of course.....

"you may hear a certain variation in RPM as the engine warms up"

....as Ken correctly noted......
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Old 05-04-2009, 06:36 AM   #8
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PS: You may wish to close your garage door and windows so as not to disturb the neighbors while conducting the Sarnali Charge Routine.
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Old 05-04-2009, 08:29 AM   #9
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Again my bad for not pointing out the obvious, I suppose I should add that the bike should be on the centerstand with the transmission in 2rd gear so as to impress a suitible load on the engine too though anyone should be able to figure that out.......
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