Hi guys,

Wondering if someone that knows more about these things could help me.

I was racing today and in the first race on around lap 7 I started to experience a loss of power, first of all it just wouldn't pull as much as normal in 6th, however within a lap when I changed into 5th the car just wouldn't accelerate at all - it wasn't missing or it didn't sound it anyway - it just wouldn't accelerate any more.

I retired from the race and came in, checked everything over and noticed the carbs weren't seated 100% so fixed that and went back out for the 2nd race. Same thing again - fine for about the first 7 laps and then I lost power again, so I retired once again. My oil and water temps were fine.

Anyone any ideas as I haven't a clue!?

Thanks,
Paul

Fuel vapourisation or whatever it's called?

Something for me to look into and see if that couldcause it, thanks Ben.

It really has me stumped.

Fuel starvation? How soon does it recover? Are you using std pump?

Engine seizing ?

Vapour locking. That's the fellow..... Fuel gets too hot in the carbs turns to vapour. Suddenly no fuel to the engine. Let it cool down and it'll start. It was quite toasty and racing it will show up problems with under bonnet temperature.

That sounds possible. There was about an hour and twenty mins between races, it lasted around the same duration in the 2nd race.
Would vapour lock or whatever only show in top gears first? When it happens it'll rev out in 4th then when you change to fifth its like the engine is choked and the revs don't rise at all!

Oh and I'm using the standard pump and car was set up on rolling road.

It was also fine on a test day 2 weeks ago and the weather was pretty much the same.

Is there a vent into the fuel tank to release vacuum? Does sound like something is frying under the bonnet. Add more ventilation to allow hot air OUT! Wrap exhaust.

Hi Paul,

sorry to hear of your issues.. where is your pump ?

hopefully its a relatively easy fix when you diagnose....

I do have a breather vent on my tank. The car has ran fine in the past under race conditions.

I'm hoping it fuel vapourisation, we blocked off around the radiator to force all air threw it as water temps had been high in the past. I didn't have the issue in testing with this setup though.

I hope I get it sorted too Mark, unfortunately I think it's going to be hard to diagnose the problem or tell if its fixed. My pump is at the back below the tank, never had an issue with it!Yesterday was rather annoying!

[Edited on 27/6/10 by PaulYDP]

quote:

---

Originally posted by PaulYDP
I do have a breather vent on my tank. The car has ran fine in the past under race conditions.

---

Ok will do - thanks Bob!

Carbs icing up? Well known problem on Ninjas, not just confined to cold weather...