Sprint 1050 Engine Draws A Lot Of Power When Running

Stew985 · Aug 23, 2025

I have a 2007 sprint st 1050 and have had an electric issue.

About 5 years ago my stator and regulator died, I think due to riding in the city slowly in extremely hot weather.

I changed them and it's been fine up until now and they both went again.

I have now replaced them again but the power draw is very high.

I have taken out all the fuses that aren't needed to run the engine and unplugged the headlights and the draw from the regulator is almost 20amps.

When it's not running I think it's about 5 amps from the battery.

When it was running I tried disconnecting the battery and it does run but barely, you can see the running lights flicker and it misfires if I rev the engine.

I'm about to pull the tank and test circuits but seeing if anyone here has experienced this before.

I'm guessing it's something that's only on when the motor is running or a partial short on an engine run circuit.

joe mc donald · Sep 6, 2025

Stew985 said: ↑

I have a 2007 sprint st 1050 and have had an electric issue.

About 5 years ago my stator and regulator died, I think due to riding in the city slowly in extremely hot weather.

I changed them and it's been fine up until now and they both went again.

I have now replaced them again but the power draw is very high.

I have taken out all the fuses that aren't needed to run the engine and unplugged the headlights and the draw from the regulator is almost 20amps.

When it's not running I think it's about 5 amps from the battery.

When it was running I tried disconnecting the battery and it does run but barely, you can see the running lights flicker and it misfires if I rev the engine.

I'm about to pull the tank and test circuits but seeing if anyone here has experienced this before.

I'm guessing it's something that's only on when the motor is running or a partial short on an engine run circuit.
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@Stew985 Welcome. And yes seems like a short some where. There was a lot of people who relocated their rectifier / regulator to keep them cooler.

Pegscraper · Sep 6, 2025

That is way too much current draw IMO. I’d expect around 10A max from the ignition and EFI systems, less if it’s carbs. Does the bike have ABS with a separate ABS fuse?

Disconnecting the battery while running isn’t such a good idea, especially with modern onboard electronics.
The battery acts as a secondary voltage stabiliser, I remember doing this on my Capri years ago with the sidelights on and it blew two bulbs. Fortunately, the new Sharp radio cassette player I had recently fitted was switched off, otherwise it could have proved expensive!