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Just got back from a ride and have for the second time in so many days experienced an issue with WOT. Scoots running well but on the odd occasion I get an empty road and the chance to see what top speed I can achieve, once the throttle is fully open and just about bottomed out. The engine dies, but then runs fine.
I thought on both occasions that it had seized, and pulled clutch in and coasted to a halt. But the engine just returns to normal idle. I thinking that it's a momentary loss of fuel for a split second, but what's causing it???
Scoot: GP150. Ports cleaned and exhaust and inlet opened up. 22 jetex with 45 pilot, correct slide and 118 main. Sterling exhaust and runs really well sinice the work on the cylinder.
Could the float be sticking ? Seems fuel related.
Carb is running well with Dellorto jets.

Any ideas lads?

check your flow rate from tank.......could be a slow or blocked tap

I'd use a bigger main jet with an expansion pipe.

I was running a bigger main but it was too rich. Flow rate could be something. Think I read somewhere that the hole in the body from where the banjo fits and and fills the bowl can restrict flow. And drilling it out could help, but what size?
Any ideas?

Cheers

Does it rev out ok in 3rd gear?

It sounds like a soft seize.

Fast n Furious wrote:Does it rev out ok in 3rd gear?

Yes it does

Cheers

Hi

My LI used to do this but I had an Breath sweet on it, all was fine when running but when I was at full throttle and had to come down the gears I lost all power it was the Breath sweet elbow being squashed on the side panel. As soon as I took off run all OK.

So check this if you have one on..

Is there enough movement on the float so that the bowl can fill up with enough fuel? That is, have the mounting arms of the float been compressed by accident so that the bowl stops filling earlier than it needs to?

Mark

Just come back after a spin and it's running like a bag of........
Bogging and not revving. Going to put the PWK back on tomorrow, just to see if it improves matters.

Oh dear good luck for tomorrow then

I've had the replacement rubber tipped float needles with the red tip be about 1mm longer than the standard one.

It runs fine until you go flat out for any length of time, then it just dies like you're running out of fuel, then you shut off for 30 seconds, then its fine again.

check the length of the float needle against the original one.

Leotech wrote:I've had the replacement rubber tipped float needles with the red tip be about 1mm longer than the standard one.

It runs fine until you go flat out for any length of time, then it just dies like you're running out of fuel, then you shut off for 30 seconds, then its fine again.

check the length of the float needle against the original one.

That's one thing I've not replaced for Dellorto. I will have a look as you suggest.
Did it solve your problem?

I've had a few different carbs recently, but keep coming back to the Jetex for some dumb reason I can't explain. When they run well, they are great little carbs, but they do seem so temperamental. Just when you have it set up and alls well with the world, then the next it's playin up. And to cap my bad day off, the Mrs recons the grout in the bathroom needs more urgent attention than my scoot

P D: SC Chester wrote:...... And to cap my bad day off, the Mrs recons the grout in the bathroom needs more urgent attention than my scoot

Your Missus could be right...

Ha ha, he's a pushy cat compared to the boss of this nick

Update:
OKO 26mm with power jet has resolved top end issues.
Took scoot out and bottomed out in 4th. No issues to report.Ran well, no fuel starvation or soft seizes. Does a GPS 55mph and 80 mph on a Lammies liar speedo .
Cruises nice at 40.
Shame, about the Jetex, but mine just ain't consistent.

As you were