Charging issue + Hot start issue

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Joined: Sat Jun 29, 2019 10:57 am
My Bike: ZXR400 L9

Charging issue + Hot start issue

Post by peasling » Fri Sep 04, 2020 11:30 pm

Evening all, hoping someone can lend a hand.

So I have had ongoing charging issues with the bike (l9). The battery is not charging as it should and also suffers from the infamous hot start issue - possibly connected?

I've tested the stator - all good getting about 45acV out at 4krpm. Replaced the regulator with a brand new one, still no joy. Working my way around with a multi meter the regulator is outputting increased DC voltage (13~14.5dcV) at the white +ve wire at the regulator plug. So stator and regulator are working as they should but for whatever reason the battery still does not charge. I've tested the +ve white wire at the main 30amp fuse switch and it reads a steady 12v no matter what rpms are. So somewhere between the regulator end of the white +ve and the battery I am losing my charge. Any ideas what may be causing this?

Other issue is with hot starts. From cold starter motor spins fast as it should and bike fires up perfectly. If the bike gets up to normal operating temp and I turn the bike off and back on again the starter motor sounds like a it's not getting enough power (slow to turn over like it has a flat battery). Leave it to sit for 10mins and she's good to go again. I've renewed the earth and positive cable to the starter motor. Starter motor itself has also been replaced, no change in behaviour between the two. I can only assume the issue is an increase in resistance within the loom when hot. I've poured through similar posts and see a few mentions of the CDI being a possible culprit?

Any advice anyone can offer would be greatly appreciated. Has anyone else faced similar issues and how did you resolve it?


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Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Charging issue + Hot start issue

Post by banner001 » Sat Sep 05, 2020 11:51 am

I replaced my loom and got a more powerful battery, that cured my hot start where the starter motor sounded like it was dying

As for your white wire, if you look on the electrical diagrams this goes from your reg rec to your ignition, starter relay and fusebox... I would get the bike fired up and check voltage at each of these 4 points. This will let you know if there is an issue in the wiring and in what section it is bad.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

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