Slow cranking . . not a flat battery.

[Dan88]

Hi, I have a 1989 3SK FJ1200. When I try to start the old girl engine turns over slow as if battery is flat, even though it is a new fully charged battery. I have done different check suggestions from workshop manual! and the only thing that stands out is a voltage drop of "1 volt" at the ignition switch prior to cranking. I'm wondering if this would be enough to cause the problem. When I connect jumper leads from the car the engine cranks over like it should and starts without issue. Any thoughts out there? Regards Daniel

[Arnie]

Any voltage drop certainly won't help, but the starter has its own heavy duty circuit interrupted only by the starter relay. So, if the relay connects, you should be getting full power.  You can clean and inspect the cables and terminals from the battery to the relay and then to the starter.  That might help.

You can also clean, service, and lubricate the starter. 
If its never been off the bike, it is probably due for some love.
Clean the bushings at each end of the armature, clean the commutator surface and remove any debris in the gaps, check the condition and length of the brushes, and
re-assemble with new grease on the bushes.

Arnie

[Nova]

How many cranking amps is the battery? If it's starting normally with a jump or a boost then it sounds like either something is wrong with the battery or it is just too small in the amps to turn it over. Looks like the standard OEM batter should be around 190-200 CCA.

[Nova]

Another thing I was thinking about is I seem to remember something about a battery with a bad cell could seem fine until it gets a significant draw. That would account for the drop in voltage as well as the inability to crank the engine very well. But with a low draw it would still read 12 volts.

[Pat Conlon]

Assuming the battery is not at fault, then check your ground wire to the engine case. Clean all connections.

[oldktmdude]

Another thing I was thinking about is I seem to remember something about a battery with a bad cell could seem fine until it gets a significant draw. That would account for the drop in voltage as well as the inability to crank the engine very well. But with a low draw it would still read 12 volts.

+1. It's not unheard of to have a new battery with a problem. Pat, your response could also be correct but if it starts with a jumper, that could rule out a bad ground connection. (depending on where the jumper is connected to, of course)
Regards, Pete.

[Country Joe]

I second Arnie's thoughts. I did all the things that he mentioned and found that the screws that connected the brush leads to the terminals were very loose. The tabs on the brush leads showed evidence of overheating and was probably a significant factor in the slow cranking that my bike was exhibiting.

Joe

[Pat Conlon]

Hey Pete, yea I thought about that, but when Dan said that he jumped the FJ battery with a car battery and the "engine cranks over like it should and starts without issue" it got me thinking....

Hooking up to a big battery can push through current that normally would flow poorly thru dodgy connectors.

Good advice given on the starter brushes.

Cheers lad!

[moparman70]

Is this when cold or only when hot --- there is a trick when hot -- if when cold then never mind see the other answers

but if Hot then I can elaborate

sc

[Dan88]

Thanks guy's for all the advise! much appreciated. Ended up being a starter motor issue, put a new set of brushes in and all good now. Mine is the model that has a two brush set, guy from the bike shop said the four brush model is better! I believe that if I can find one of these starter motors it will pop straight in? Thanks again.

Dan

[Pat Conlon]

Yes, the 4 brush XJR starters are better and they fit....see RPM.

Beware the Chinese knock off's. There are certain times when eBay is not your friend.

[krusty]

We had a VJMC ride yesterday and one of the guys had the hot start problem with his 1200. It has a new (2) brush kit but it's still a very reluctant starter when hot. I'll get him to check his battery specs but otherwise could you post  a link for hot nonstart fix please?

[Pat Conlon]

.....could you post  a link for hot nonstart fix please?

What link?

Arnie nailed it with his above post: check the battery and connections (inc. ground) and service the starter motor.

Several FJ owners have mentioned that slightly cracking open the throttle plates help the hot start issue.

A healthy 2 brush starter struggled with my engine, but I've never had a problem with the XJR starter cranking over a heat soaked 1350cc engine on a hot summer day.

[moparman70]

per my post -- earlier when hot --- and yes to what Pat says about cracking the throttle.

Occasionaly when hot ( typically on a long ride and stopping for a quick fuel stop ) you will get the slow cranking sound start -- simply crack the throttle past half a least ( I think I full throttle it) and she will crank over and start like a champ .

my experience for what its worth

Its been said by other members too if you want to search posts

sc2

[racerrad8]

RPM does stock genuine Yamaha 4 brush starters.
Genuine Yamaha 4 Brush Starter

Robert - RPM