'Galloping' idle and stalling when restarting from hot

[dazzler24]

The temperatures are climbing here again at this time of the year (35C+) and on my last two runs I've noticed an undesirable issue that's crept in to harsh my riding buzz.

What has been happening is that after stopping at e.g. controlled road works where the delay is extended for a few minutes I tend to shut the bike off with the key before the fan kicks in and/or I roast from the radiated heat.

When it's time to go I key on and wait for all the 'stuff' - pump, electrics etc to settle before hitting the starter.

The bike will start but suddenly I've got a 'lumpy' cam installed and the bike kind of 'gallops' at idle and has stalled a few times requiring a restart where I've got to twist the wrist slightly to keep the revs up until I can get moving.  Not a big deal but hasn't happened before and has been repeatable so I thought I'd ask the brains trust if there is anything sinister I should be looking out for.

I should note that the bike starts and runs fine from cold.  If I've been off the bike for a bit somewhere and restart after say 10mins or so the 'galloping' is detectable but settles soon after and all is good.

I'm getting close to a service so it may just be that she needs a TB sync?

[Windster]

I have exactly same problem on my 16' Tracer. I think it could be many thinks. In a month or so I will be doing some tweeks with the bike ( new brakes 320mm and lines, Ape cam chain tensioner, new clucth basket dampers) and I will try to sort this problem. Wil start with:

TB cleaning and synching.

Check for vacuum leak.

Check AIS system

Check for gas tank ventilation.

Check fuel pressure especially at starts.

Will additionly check spark plugs and valve clearances as I recenty had a problem with chain tensioner at low rpms.

 

 

 

 

[dazzler24]

The first two on your list and the valve checks were on my mind as possibilities as well.  It'll be interesting to see what you find.👍

[2and3cylinders]

It may be a FI form of "vapor lock".

Before your next ride grab a spare ignition key and have it in the fuel cap and try to simulate the issue.  If and when it happens, open the fuel cap and determine if the issue clears relatively quickly.

I think it may be a temperature sensor going off or a combo of them.

Did you turn off the fuel cut and AIS functions (and remove and plate off the later feature) with your ECU flash?

Also, blow-by in high temps can sometimes be excessive which can foul the filter and TB. 

TB sync and valve lash are not as likely if the issue is not and issue when starting and running hot but not excessively so but not shutting down then restarting.

Fuel over-richness due to a temp sensor not leanness is suspected.

An ignition advance delay or retard due to a intake temp sensor may be involved. 

Being a 15 (and 16), have you checked for trouble codes? Does the Shop Manual troubleshooting guide shed any light on the problem?

GL Mate and keep us in the loop. 

High of 35 here today, F not C...

[dazzler24]

12 hours ago, 2and3cylinders said:

It may be a FI form of "vapor lock".

Before your next ride grab a spare ignition key and have it in the fuel cap and try to simulate the issue.  If and when it happens, open the fuel cap and determine if the issue clears relatively quickly. - OK but will have to try and simulate this on the side of the road and not in traffic.

I think it may be a temperature sensor going off or a combo of them.

Did you turn off the fuel cut and AIS functions (and remove and plate off the later feature) with your ECU flash? - Injector cut off was applied but AIS was left on as I had the stock pipe at the time, however, I have removed the AIS hardware and installed block off plates.  I assume that does the same thing i.e AIS now removed?

Also, blow-by in high temps can sometimes be excessive which can foul the filter and TB. 

TB sync and valve lash are not as likely if the issue is not and issue when starting and running hot but not excessively so but not shutting down then restarting. - 👍

Fuel over-richness due to a temp sensor not leanness is suspected.

An ignition advance delay or retard due to a intake temp sensor may be involved. 

Being a 15 (and 16), have you checked for trouble codes? Does the Shop Manual troubleshooting guide shed any light on the problem? - I haven't as yet but would have thought an error code would have been thrown?  But will check in the diags anyway.

GL Mate and keep us in the loop.  - will do.

High of 35 here today, F not C... 🥶

Thanks 2 + 3.  As usual, you are full of useful and well thought through advice.  Check my replies inside the quote above.

Cheers.