Yamaha TRX850 Enthusiasts Forum

The other week I was out on a short run and stopped somewhere for 10 mins. Upon starting, it would just catch when it started to first turn over then nothing, just the starter motor turning the engine over.
My fuel lines were a little twisted so I thought this was the issue, nope. I thought blocked fuel lines / filter, nope. Eventually got the bike recovered and upon checking the plugs it transpires there is only one initial spark on the LHS (nothing on the RHS) then nothing until you try starting again. The only change to it was about 3 months ago when I fitted new ignition leads as it was running badly in the wet and at the same time I replaced the resistors in the plug caps with a small piece of copper tube. Other than it running better in the wet, there was no other discernible difference.

I’ve read as many threads on this including this one http://www.trx850.com/phpBB_forum/viewt ... 6&start=15 but that seemed to revolved around a rebuild and a new ignition, this was running fine before it died. I have limited spares to try swapping out components other than spare plugs. I’m in Sydney but going to the UK in a few weeks where I hope to collect some spares to bring back in hope of finding the cause.

Can anyone suggest a shopping list of items that would be the first to replace e.g. CDI, coils etc?

Thanks all.

Did you try this? Perhaps your ignition barrel is not working correctly.

Snod Blatter wrote:Did you try this? Perhaps your ignition barrel is not working correctly.

That was the thread I mentioned above.

>>The other two smaller striped wires are triggers to the ECU . They have to be joined together otherwise you ECU will get 1 initial spark and then go to earth and no spark .
>>That's how I got mine running with an after market two pole key ignition switch.

My reasoning was that the ignition wiring was working fine before it stop working and to join wires that have remained un-joined for 20 years wouldn't logically be the answer. I thought that cobbadiggabuddyblooo fix was because he was fitting a new ignition.

I thought that cobbadiggabuddyblooo fix was because he was fitting a new ignition.

It was, but if the ignition switch develops a fault then 1 spark and no go is the result.
You seem to have one 1 spark and no go, so have you checked that the ignition switch is working correctly?
The sidestand and clutch switches also affect the control wire (Blue/Yellow) from the ignition switch, so it might pay to check them as well.

No good point. I'm not adverse to checking if its working but I have no idea how to test it. I went to check the side stand and look for the resistance with a multimeter but tracing the cable from the SS, it seems to join the main loom and not have a connector I can plug into.

Have you checked the safety cutout relay. It is located next to the indicator relay, it is activated by the side stand switch, clutch switch and neutral switch.
I bought a spares bike, which the owner told me he could not get to start, he thought it was the ecu, it turned out to be the safety cutout relay, which I bypassed to get the engine running.

How did you bypass it, just remove it?

PlentyMech wrote:No good point. I'm not adverse to checking if its working but I have no idea how to test it. I went to check the side stand and look for the resistance with a multimeter but tracing the cable from the SS, it seems to join the main loom and not have a connector I can plug into.

Cable from side stand switch has a connector, or should have, about 30 cm up from the stand. No need to measure and check, just short the two connectors to bypass the switch.

I used some short wires to join the connections in the plug, will take a photo and link it in.

Solved.

It was the same ignition issue cobbadiggabuddyblooo had. I connected the two non-power wires from the ignition with a scotchlock and it fired up straightaway.

Thanks all and SodB latter & Dicky especially.

Hi all,
I am having similar no spark issues as others but cannot find the problem.
Bike will fire and run...start stop start stop and then nothing, no spark.
Thought it may have been a little corrosion on the ecu box under the seat and it fired and ran, restarted and ran several.times but tried again several.hours later to start and nothing???