I have a 2004 Yamaha FZ6N and quite some time ago, the idle started randomly dropping below 1000, with sometimes going below 600 and eventually the engine is turned off. i also noticed that when this happens, if I rev the engine a bit, the bike turns off as well.

I started looking online and found out that the FZ6, together with some other Yamaha models had some issues with the TPS where an recall was issued. So I told my motorcycle mechanic this and checked out the TPS and according to him, it was not faulty but rather required some servicing.

The bike ran smoothly for a couple of months after this but now the issue started happening again, so I went again to my mechanic and he told me that sometimes the TPS needs to tweaking which he does when he is doing a service to a bike (this I found a bit funny to be honest).

So he gave me the bike back and the issue is still there, so I called back and he now told me that the TPS was perfect when I last took the bike and he had just adjusted the throttle body position (if that makes sense).

He now told me that he won't be able to troubleshoot this properly unless he is riding the bike and the problem occurs, but the problem occurs randomly, sometimes weeks apart.

However, I am now noticing that if I do not ride hard, then the problem does not occur, but if I start accelerating quickly, then there is a high chance that the problem will occur.

I also noticed that sometimes, the idle goes up rather than down, somewhere in the line of 2100 rpms.

Whenever the idle problem occurs, whenever I switch on the bike, the idle goes back to normal (1350-1400 rpms). Logically, this seems like an electrical problem and not a mechanic one, since if it were a mechanical one, it wouldn't go away when the bike 'resets'.

I also noticed that this problem started some time after installing a slip on Two Brothers exhaust. I did some digging online and it seems that Two Brothers are known to cause random idle problems. Maybe a remap is required? I did not do one since as far as I know, a remap is not required for a slip on exhaust. I still find it strange that the exhaust is the problem since the problem disappears as soon as I switched off/on again.

Do you have any suggestions regarding this? I would really appreciate it

  • Have you checked the tps yourself? I've not personnaly heard of a mechanic tweaking the tps during a service(unless of course you ask for them to check it etc). I had a honda with a dodgy tps and it was intermittent like yours, sometimes fine for weeks and then back with a vengence. I'd check it youself, find the reading in the workshop manual and backprobe the wires with a multimeter. – DamoC Sep 8 '19 at 10:38
  • Yes I told the mechanic about the possible TPS problem and he checked it himself. Edited the question with some information btw. – seedg Sep 10 '19 at 20:38
  • I have read the addition. You say the new exhaust, have you changed the air filter? Is it still stock like? I would agree with you in it being an electrical problem. Although if it only happens when you ride hard maybe a temperature related air leak?? But at the start when you say it cut out when revving, that's a fuel related issue whether too much fuel or air. – DamoC Sep 15 '19 at 15:22

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