Starting Issue 850 Mkii

[Replicant]

Hello All,

 

so here are the details: 

 

New battery installed 10 Jan. Reading 15.5v.

 

Seems fine for a couple of weeks. Then bike won’t start without a jump.

 

After 15 mile ride still won’t start, making solenoid click repeatedly when trying.

 

Replace right hand switchgear as I find broken wire and bundle of wires hard and inflexible at the break.

 

So today the battery has 13.4v with key off and the solenoid just clicks.

 

I jump it and the Alternator output at idle is 16v and at 4K revs 15.5v

 

After 5 mins of running at idle I switch  the key off and the battery reads 14.4v

 

After a 3 mile ride the battery reads 15v but would only make solenoid click repeatedly when trying restart with an  engine that is still hot.

 

I check again the Alternator output: at idle 16.9v and at 4K revs 16v.

 

I check the resistance between each of the white wires off the alternator and get 6 ohms between each and infinite resistance between each to earth.

 

 

I'm thinking it's the regulator/rectifier but can't understand why at 15v there isn't enough juice to turn it over but it does when I jump it from another vehicle.

 

If anyone has any ideas, much appreciated

 

Regards

 

[leehenty]

Check brushes in starter motor

[Catteeclan]

Are those readings from a trusted meter? 16.9 volts is a little on the high side for comfort but that's a different prob than the non starting. 

You can use a meter to test the output from the solenoid and then to the starter, you'll check the starter cable at the same time. Check the engine earth is good too, easy way is double up with a jump lead.

Starting motor bushes could be a good call too.


 

[Snowbird]

Check starter and all connections, gotta be between battery and starter.

You could disconnect big cables from solenoid and check resistance across it while hitting the start button.

[fixitsan]

Look at the grounding system.

Battery to frame, frame to engine, install a jump lead from the battery negative terminal to the engine ground and measure those voltages again

[Replicant]

Thank you all for commenting.

 

I'm interested in the comments about 'frame to engine' grounding. I always assumed as the engine is bolted to the frame (and the battery is bolted to the frame) this is direct contact therefore there is continuity of ground but I'm inferring from the comments that there is some other connector or connection that completes this continuity. If so, where is this?

 

Regards

[bjorge]

When the solenoid just clicks, do dash lights keep their brightness?

[fixitsan]

Thank you all for commenting.

 

I'm interested in the comments about 'frame to engine' grounding. I always assumed as the engine is bolted to the frame (and the battery is bolted to the frame) this is direct contact therefore there is continuity of ground but I'm inferring from the comments that there is some other connector or connection that completes this continuity. If so, where is this?

 

Regards

 

 

A simple test is to measure first the battery voltage from + to -, then measure battery voltage from the battery's '+'  terminal and ground somewhere on the engine, like an alternator or engine casing bolt. The two readings should be close to identical.

 

I learned in the past that just because it's solidly bolted to the frame, corrosion on frame-engine bolts can start to develop high resistance which is enough to limit the amount of current the starter motor can draw.  There should be a thick cable from the battery's '-' terminal and the engine, or at least one from the frame to the engine. It's an unusual fault, and might not be your issue. On my old KZ550 the absence of the grounding wire made the starter turn very slowly

 

As stated already the starter motor could be the culprit, and a jump lead from the battery positive to the supply for the starter motor will tell you if that's the problem. The solenoids themselves can be a problem. so bridging the solenoid terminals to see if the motor spins can eliminate that. Expect sparking when you do these tests, be very vigilant not to let '+' and '-' from the battery touch together

 

Another check can be of the battery voltage when you're engaging the starter, how low does it drop ? If it drops much below 10V then the battery could be old and sulphated. Sulphated batteries can still reach a high voltage when charging, but the plates can be shorted together with crystals which reduces the maximum available current when a high load engages, such as the starter. Some people buy battery load testers to simulate this test

This post was last modified: 11-03-2026, 12:25 PM by fixitsan.

[Andy25]

Starter Solenoid is only about £15 its amazing what faults a dodgy one of them causes 

I've had issues on the 850 ,900 and lately on my Sons MT07  ( showing Crank case Sensor fault ) all starter Solenoid faults

 Could be a Cheap fix to rule out before spending lots of Time chasing mysterious faults