Yamaha TRX850 Enthusiasts Forum

When I bought the bike the previous owner said the bike had an attempted theft where the wiring to the ignition had been cut with an attempt to hot wire it. After they were reattached the bike no longer runs on the side stand without the clutch held in. The moment you release the clutch it stops. Now I don’t know whether the attempted theft has anything to do with it or the previous owner knew something else was wrong but I checked the clutch and side stand switched and both seem fine. Any other ideas? I guess it still points to the wiring loom elsewhere and probably related to the side stand switch because if you sit on the bike with the side stand up it’s fine.

Hi Dsanty!

IIRC, the side stand switch is connected to the ignition unit just for this purpose.

Checking the wiring diagram* will surely bring light to this matter.
(* I think also available in the downloads section here?)

Pointing greets from Munich!

Hi Holer,
If only it were that simple. Putting the bike on a paddock stand and tried a few combinations:-
1. Side stand down - clutch lever not pulled = no start
2. Side stand up - clutch lever not pulled = starts and runs
3. Side stand down + clutch lever pulled = starts and runs until clutch lever is released which causes motor to stop
4. Neutral light is on so Neutral switch is working. Right?

My question to you is will your bike start with SIDESTAND DOWN but WITHOUT PULLING IN THE CLUTCH? According to the electrical diagram - it should I think because the circuit is made through the neutral switch. Mine wont start but the starter motor turns it over.

Thanks in advance.

Doug

Hi Dsanty!

1. Side stand down - clutch lever not pulled = no start

Correct behaviour when in gear and starter motor not turning

2. Side stand up - clutch lever not pulled = starts and runs

Correct behaviour (must be in neutral)

3. Side stand down + clutch lever pulled = starts and runs until clutch lever is released which causes motor to stop

Correct behaviour when in gear

4. Neutral light is on so Neutral switch is working. Right?

I guess so.

My question to you is will your bike start with SIDESTAND DOWN but WITHOUT PULLING IN THE CLUTCH?

Yes but only when in neutral.
Then, when disengaging the clutch and shifting in gear, the engine will stop as intended.

Mine wont start but the starter motor turns it over.

That's not a correct behaviour!

Seems that rewiring after the hot wiring attempt wasn't correct.

Again: The only thing I can recommend is checking the actual wiring against the wiring diagram and/or measure what is connected with what.

Time consuming but I see no other possibility.

"Wishing you luck" - greets from Munich!

Thanks Holer. Wish me luck

Options are, disconnect the side stand switch, you might need to loop out the side stand connector. Problem is you can have it fall off if it's in gear.

Another is to look to see if the wire from the neutral light to the cut off system is still there.

The bike thinks the bike is in gear.

It's at time like this there was a program where you can feed a wiring loom into it and then simulate the connectors to work out the possible locations for faults.

The service manual has a decent diagram showing how it works.

You can start the bike IF
it's in neutral
OR
the clutch is pulled IN AND the side stand is UP

Picture here if you haven't downloaded the manual yet

If the switches are working OK then trace the wiring back to the start circuit cut-off relay and check that the voltage on the pins follows the state of the switches.

Hi Dsanty!

Just detected an error in my answers

This
3. Side stand down + clutch lever pulled = starts and runs until clutch lever is released which causes motor to stop

Correct behaviour when in gear
is not true!

The combination of side stand down and in gear causes the starter motor NOT to turn.

I'm very sorry to have certainly confused you!

As dicky said:
Starter motor is turning
- when in neutral (irrespective of the states of the side stand and the clutch lever!), and
- when in gear, only when the side stand is up and the clutch lever is pulled (clutch is disengaged).

In other words:

The behaviour you described in #3 is not as it should be and is quite weird.

Again: It is the starter motor which is prevented from working when the side stand is down and bike's in gear.

When the engine is already running, bike's in gear and the clutch lever is pulled and then the side stand is swung out - then the engine will (has to) stall.

"Really sorry for my error" - greets from Munich

Spent a couple of hours going through the electrical diagnostic checks in the manual. Checked all switches (ignition, clutch, neutral, side stand, interconnecting wiring and start relay and everything seemed fine apart from the side stand switch readings were a little high and inconsistent. Shorted out the switch near the plug and will put it all back together for a test run.

The other thing I didn’t mention is that whilst riding it home after purchase it cut out 4 times which was a bit unnerving and wasn’t sure it was related but I think it might be the side stand switch again with a high resistance cutting out the motor. That is why I want to take it for a run to test everything out. If ok I’ll replace the side stand switch and it should be good to go.

My money is on the side stand switch as the culprit.

"Curious to know the reason" - greets from Munich!

Good chance its the switch. For each time you land the front wheel down from another wheelie it's enough to make the sidestand move a bit and the already rubbish connection causes the bike to crap out.

I remember stopping to help a lad who had pushed his bike over 2 miles in the dark up and down some mighty hills. Each time he would put the bike in gear it would cut out. I disconnected the side stand switch and just plugged the two ends together. After he had finished swearing he then rode home.

No issues on test ride. Might leave the switch shorted if they create problems.

Thanks everyone for your help.

Next issue….

Hi Dsanty!

Thanks for telling us - but I'd try and get a working side stand switch.
Maybe some cleaning and lubricating will do the job?!

On my Racetrack-TRiXie I also have a side stand with no switch and there I'm used to it.
But on my street legal TRX I prefer having a working side stand switch - last nut not least to satisfy the TÜV engineers. ( ;o)

Street legal where necessary greets from Munich!