Electric starter won't crank engine on GT750 - Battery chgd

[Lemans]

Gurus,

Would love to have your opinion on this. Recently left the ignition switch on for about a week and battery was dead. Purchased a new AGM battery from auto store as it was under warranty (just at a year old). Charged new battery at home and electric start was working. One week later, it sounded like there was not enough juice in battery when starter was engaged to start the bike. Connected battery to charger and battery was fully charged 30 mins later. All electrics work fine (headlight, horn, turn signals etc.) except electric start. Again sounds like battery does not have enough juice to turn crank. Kick started it and it started right up and idled fine. Tested the battery with a voltmeter and read at 12 volts and at 3000 rpm about 13.6 volts. Battery seems fully charged, never had an issue with electric start before. Bike was always half button start. Any ideas what may be happening? Thanks!

[Cliff]

Does the solenoid click when you hit the start button or does everything go dead?
Clean and tighten ALL the connections, including both ends of the ground cable and positive cable and the fuse connections!
One corroded connector is all it takes, and with the key turned on for a week, the corrosion will have heated up and you might have just a bad connection somewhere!

[Lemans]

Solenoid clicks and starter weakly engages. Will try to clean and tighten connections per your recommendation and update.

[GT750Battleship]

Hi,you are extremely lucky you didn't fry the coils by leaving the ignition on !
Back to the starter motor,my "A" model displayed all the same symptoms as yours is doing...spent a lot of hours checking everything..in the end I pulled the starter motor out,to find the brushs were completely worn out!! I cleaned everything up,ordered brushs from GTReiner in Germany & now have a perfectly functioning starter motor again,good for another 30+ years...!
Cheers,
GT750Battleship.

[Lemans]

I think I'm going to tackle the starter issue. Any instructions on how to remove starter brushes for inspection? Thanks.

[Alan H]

If your battery only reads 12 volts directly across the terminals, it's almost flat or there is a dud cell. There should be at least 12.4 volts 'at rest'. 13.6 is OK with the engine running. Does the bike start off the electric start if you run the engine to warm, then turn it off and try for an immediate start?
With the lights on, does the headlamp almost go out when you try the starter?
As the others say, check ALL connections and clean them especially earths and earth cables, also the starter motor brushes (do them last as access is a tw@!)

[GT750Battleship]

I think I'm going to tackle the starter issue. Any instructions on how to remove starter brushes for inspection? Thanks.

Hi,fairly big job...I've done it.. A Workshop Manual would be handy before you start the job,or or having someone to help that may have done this job before ? Disconnect battery,remove tank as air box mount bolts are under it.
Take out air box,comes out from the right..I'd disconnect the oil pump arm from the carbie
pull carburettors from rubbers,drain coolant,remove starter motor cover after disconnecting water by-pass hose...cover will slide up the hose & come off out of the way.The water by-pass pipe has to come out to allow the starter motor room to be moved sideways & un-mesh from its gear drive to the starter clutch..this it does very easily,once starter motor is out,before undoing anything..scribe some marks on the starter body so you know how it all goes back together the right way !!
If you don't feel confident in affecting a repair to the starter motor I'd take it to an Auto Electrician ?

Cheers,
Roger.

[Lemans]

Ended up being a bad battery! Electric starter works great ... half click start.

[Alan H]

I put one similar to this on the GT550, they are the bee's knees and really spin the engine over well.
http://www.ebay.co.uk/itm/Suzuki-GT-750 ... 46085362e3" onclick="window.open(this.href);return false;

They are VERY well thought of by folks with electric start triples.

[Lemans]

Thanks

[pearljam724]

I had the same so called new battery issue a couple summers ago. I learned my lesson. Always put the battery through those series of tests as soon as you buy it. Some batteries sit on shelves for too long without maintenance. Check the manufacturer date too. If it's more than a few months past. Skip on it. Even though, things have worked out for you. As Roger stated, pull the starter one day when you're looking for something to do. Inspect the brushes and clean the commutator with a 1000 grit piece of sandpaper. Then touch it up with some electrical cleaner. That's probably over due. As brushes break down. They will coat the commutator that is made of brass with a sooty carbon. Plus, the brass oxidizes and wears. Very delicately sanding it smooth will fix those issues. Those issues will create a bad electrical connection with the brushes. The starter needs cleaned and maintained like anything else. Very simple thing to do. For future reference. If you suspect the starter. Remove it and hook it up to a battery. The drive shaft should spin, if the starter checks out o.k.

[Lemans]

Thanks

[joandon@telus.net]

I ordered a rectifier and a voltage regulator from Oregon Motorcycle Parts for my 1972 Suzuki GT750.

Simple, easy installation. I disconnected the battery and uninstalled the original one that came with the bike.
The bolt holes lined up perfectly and the connector was identical with the Suzuki one, with the colored wires in the same positions.

I reconnected the battery and tried the electric start. It would not engage. Didn’t even try.

I disconnected the battery, removed the new one and reinstalled the old one. Electric start started the bike immediately.

Anyone else have this experience? Any advice would be welcome...

[Alan H]

Suzuki triples had separate regulators and rectifiers not combined units. What connectors are on the new one you bought? There should be one that goes to the alternator with 3 x yellows and a green, one with green, orange/white and black/white (regulator) and one with black/white, red + 3 x yellows (rectifier). Trouble is, some wiring on the combined units is internal, plus the bike wiring may have been 'adapted' to your original to make it work.
When you switch the kill switch on, the electric start should work as that's the only thing on that particular (start button) circuit, but the kill switch also switches power to the regulator and coils.
Why did you fit a new unit? Did the old one not charge?
Wiring diagrams here - viewtopic.php?f=29&t=4743&p=107616&hili ... am#p107616