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Malleus

MT-09 Hot start issue

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Hi all,
So over the past 6 or so months I have been having an issue starting the bike when it is hot (+80 degrees) This only occurs when warm and when the ignition is turned off fully. If I kill the engine and restart it starts just fine. When it is hot and the power is turned off - the bike will not idle, I can get it to go with some throttle, but this is risky as it will still drop below 1kRPM if this is not maintained. I have had no time to really investigate this myself so finally I thought I would drop it off at motorcycle repair shop. After 1 week and lots of phone calls it is not solved. I have asked them to email over what they have tested and received this:

"Just to confirm that the following has been undertaken on your bike. Firstly the battery was fully charged and the spark plugs replaced. After speaking to Yamaha technical they suggested that a number of the bikes temperature sensors be checked to ensure that the temperature differential was correct, this has been completed & no issues found. This results in the bike starting fine when cold and with application of a bit of throttle when warm.At this point Yamaha technical has suggested that the next stage is to strip the bike and investigate the wiring loom. As the bike is now out of warranty this cost would be passed onto yourself, we initially estimate that this investigation could take 3-4hrs minimum which would be charged at £75hr + VAT." - (Plugs were checked and cleaned and battery fully charged when the issue first appeared and I had told them this!)

Now I do not want to pay £75 x 4 for possibly no resolution, but looking at forums I did see that some people had luck fixing this with either a throttle body sync or by flashing the ECU with the latest stock version. When I said this to the shop they said 'throttle body sync' would have been picked up with the diagnostic tool and that they 'cannot download the latest ECU from yamaha' anymore.

Does this sound right? Does anyone know a dealer in the London area that can reflash the ECU with the latest stock version? 

Also AFAIK the throttle bodies do not have any diagnostics to detect the vacuum (could be wrong.)

So again looks like this was a waste of time and I will have to set some time aside to investigate myself. Any advice appreciated. 

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Only thing I have seen about this is that folks are turning on the kill  switch (from off position) BEFORE they turn on the ignition. On the FJR I turn the ignition on then hit the kill switch then hit the starter, so I'm suggesting you try :- Hit the kill switch first then turn on the ignition then hit the starter, might work? It does sound like vapour lock from a hot engine tho, not sure if you get the same thing with injectors as with carbs?

Found this https://www.pilotsofamerica.com/community/threads/vapor-lock-carburetor-vs-fuel-injection.22320/ It's for aircraft engines but the same principle applies really, well not the flying bit obviously actually if you ride like I do then maybe it does...! :D

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Snatchy trhottle response appears to plague a number of modern bikes these days from new. Its staggering that they can be supplied like this by the manufacturer. Updates do become avai;lable.

Just a thought, but it may be just as cost effective to have it on a dyno, with the potential to have the ecu reflashed 

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Interesting read. I would assume though that vapor lock would occur when the engine is shut down regardless of whether the ignition is still on? Which is not the case here. I will see if fiddling with the killswitch does anything. tbh i never use it and it is always just off with the key.

Its such a niggling issue that i have left it for ages. Just made me crap myself a few weeks back when I left the petrol station having to sustain throttle to keep it idling, tried to beat the lights at a junction and whilst shifting down, the engine cut out, leaving me stranded in the middle of the junction (for like 2.5 seconds, but with lights all changing feels longer)

I guess one fix is when I turn the ignition off just leave it to cool down. Shouldn't be too hard in this weather! :lol:

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Do what most people do. 

Fit a power commander. It takes control of the fueling map.

You may have spent 2 or 300 quid to get it and set it up but your bike will be better and if set up properly on a dyno. Any heat issues should show to boot.

4hrs for nothing. Or a power commander and a few quid to have it set up. Seems an easy choice.

 

Or flog the bike on a cool day.;)

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On 11/27/2017 at 1:30 PM, Cynic said:

Or flog the bike on a cool day.;)

Haha.. at the peak of irritation this did cross my mind! (Also saw a brand new Street Triple for £125 per month which was tempting...)

But yea PC sounds like a good idea tbh and my thinking had arrived at a similar point. I am going to run through the basics myself when I have time (which at the moment is never - maybe I can spend Xmas day in the garage!) Then probably look at doing this next year.

Was thinking about getting a Yoshimura exhaust fitted, i figure I can justify the expense slightly more having saved on maintenance :D

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Just an update in case anyone else comes across this thread with a similar issue. Finally got round to getting the fuel tank and air box off this weekend. Synced and cleaned the throttle bodies. Issue resolved immediately - so after 8 months or so and having been in checked by two seperate mechanics (one holding it for over 2 weeks and unable to fix) it was as simple as that.
Pretty unbelieveable and slightly peeved as at the second garage, I said on the phone 'have you synced and cleaned the throttle bodies' and was told this would not be the issue and if it was it would have been picked up by the diagnostics (no idea what diagnostic there is outside actually stripping the bike down and attaching a manometer to the throttle body - but hey I am no expert.)

 

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like we always said, do it yourself as no other can be arsed.

I spent 6 months chasing a spark problem on my FZ600 and refused to take it anywhere. I got a  long thread on here about that :D

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Nice one Malleus well done for sticking with it mate. :D

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Thanks - I know you guys always say to do it yourself and I admit I didnt out of laziness and lack of time - but in the long run I have wasted more time and should have just got to it myself!

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