carb question

[Glyn Church]

I have a 94 yamaha waveblaster with a factory pipe and new SBT motor. it had dual BN 46's but I could'nt get the engine to run corectly so I went with a stock blaster carb that was smooth bored by protec. It had a 135 high and 115 low jet. I rebiult the carb to be safe and the blaster now runs like a top but with one problem. When I hold it at WOT for 10 - 15 seconds it stalls out but it will start right back up and be a little boggy at first but will run like a top until I hold it at WOT. All fuel lines are clear and the gas check valve is in and working corectly. To me I would say its sucking the carb empty at WOT. So I checked the restricker in the carb and its as small as a needle head. Any ideas? Could the restrickter hole be too small?

[Bryan Glynn]

I would say you might be running lean on the top end! Carefull!! Did you take plug readings yet? Take a compression check and make sure you haven't done any damage yet...

[Glyn Church]

Hi Bryan,
I'm being as carefull as possible. Taking plug readings and checking my compression. I have not been riding it but just taking it out to test something new I've done to remedy it. I went from 135 high jet to 145 and nothing has changed. I have a 152.5 should I go up to that? Someone else said its possibly a lean burn.

[Bryan Glynn]

You need to start rich - if you can't turn your screw out and make it overly rich, then you need to jet up, yes. You should NOT be tuning from lean UP. Make it fouling rich first, then tune back.

[Bill O'Neal]

Glyn,
The small size restrictor in the carb works in your favor here. As it is located before the return line, it is there to make sure the carb has enough fuel and fuel pressure held inside of it.
Your description of the stalling at high speed is indicative of a siezed motor. Typically, when a motor shuts itself off at WOT, it won't restart until the pistons cool enough to release themselves from the death grip on the bores.

Maybe it is time for a top end visual inspection ?
Is the motor getting louder, like clattering sounds from the pistons ?