[CDNSVS]

My 03 SVS has twice now refused to start when really hot. This has only happened when air temperature is close to 30C and the bike has been run hard (like racing).

When we come off the track after the cooldown lap we have to wait to get on the dyno so the motor is shut off to stop it overheating. Then the bike won't start. It just cranks and cranks.

If I leave it to cool for 15-20 minutes, it starts no problem. Again this only happens with high ambient air temp. Otherwise the bike starts fine.

Any ideas why a fuel injected bike would do this?

 

[evilbologna]

I'm not sure to the reason, but it's happened to me a few times. It does start for me, but it does fight it when its really hot out and the engine is hot too. I also have a '03 svs. Cold starts work so much better...

 

[phelix]

possibly a hot soak problem with the ignition sys? Does it help if u give it throttle when it isnt wanting to start?

 

[LicketySplat]

Tight exhaust valves?

 

[gsguy]

I don't know what the problem is but my '05 seems hard to start when the engine is hot (over 200*F water temp) and it is hot outside (~100*F).

As someone else said, it starts, but it does fight it a bit. I did not use any throttle when starting.

 

[cyclopathic]

Tight exhaust valves?

that was my guess too

 

[phelix]

If you had tight valves...you would have a very noticable engine miss and loss of power at all rpm's...not just a hot start problem

 

[finsvr]

It could be fuel related like fuel pump or issue with proper venting but...

Most likely it's an eletrical issue (pulse generator, faulty coil, faulty air temp sensor, fuel pump relay, etc) since most electrical failures occur when things heat up possibly causing weak or no spark, or faulty sensor making the fuel too rich or lean to ignite (although it would probably start but run crappy)

Things you can do:

When this happens you can pull a plug and ground it on the cylinder head and see if you get a fat blue spark. If you're savvy with a multimeter you can test components resistance levels compared to the service manual.

Hope this helps,

-Fin

 

[LicketySplat]

If you had tight valves...you would have a very noticable engine miss and loss of power at all rpm's...not just a hot start problem

Not if they're just slightly out of spec.

 

[DavidinPHX]

sounds like vapor lock.

 

[phelix]

If the valves were just slightly out of spec you could still have a slight eng miss when hot but you more than likely wouldnt have a hard start problem. I do valve work everyday so im pretty sure about that one. lol

 

[RandyO]

sounds like vapor lock.

+1

 

[blacktape]

it happens to me sometimes to and opening the gas cap and closing it works EVERYTIME for me. Not really sure WHY but it always works ???

 

[phelix]

sounds like a bad tank vent. Ive heard of people having clogged vents causing hard starts and even going so far as to start collapsing the tank from the pressure. Make sure you havent pinched the breather when u have lifted the tank