Discharging Fuel from Hi-Point Vents on PWK, WHY?

Curtis Bosarge · Joined: 18 Jul 2001 Posts: 28 Location: Des Allemands, La.

Hi,
Please help. I'm stumped. We run a 97 YZ125, Banke B3, BRLV pipe with a PSR-modified 38mm PWK Pump-Around system. Our main use is autocross. We have very little time/experience, so....
The carb is pushing fuel out of the two hi-point vents (slide bore area). It will fill a 20oz catch bottle in about a minute. When it does this, it also causes the motor to bog. I disassembled the carb and blew all passages out with compressd air, ensured all was clean and cranked it back up. The problem still persisted. I'm thinking possibly that the return-side pump (Mikuni) may be deteriorating, not removing fuel from the carb bowl quickly enough.
The irony of all this is that we had a near-identical problem with the 39mm TMX (bored) we were running before. Should I run a larger return line, as compared to the supply line?

Thanks in advance for any replies/ideas.
Curtis
PS: I know JR, I should have sent my used carbs to you for overhaul/updating when I got them. I just had to try it out, new-toy syndrome. You will have mail shortly. ;)

Corey Clayton · Joined: 18 Jul 2001 Posts: 53 Location: Bartlett, Il.

Curtis, when we have seen this problem it has been that the return side line was loose on the carb and was drawing air. You need to make sure and safety wire the return line on the carb. This is the most common problem, and one of the only with this system. the pump around works great.
Corey CKT Motorsports