Well expert boaters,

I would like to hear your opinion on these 2 carbs.
I found them pretty cheap online and before purchase I would like to know if anyone tested them back to back with 668 or 603 carbs and what's the difference.
Fuel comsumption, better throttle response (spool up time)...

Any info is helpful.

I can't be of much help on this one...the only ones I use really are the 257 and 813 pumper. I've used 644s in the past too. I think Scott has some experience on those you mention. Those are carbs supplied with RCMK and CY engines if not mistaking. 929 with RCMK and 771 with CY.

Those two and my ever dwindling stash of 488's is all I personally use.
primary reason is the use of the smaller inlet needle that far more accurately gets on and off it's seat offering better high rpm metering stability. at 18K rpm the needle lifts replacing used fuel and reseating 300 times per second !! .... The larger needle like you find in 257's does work generally quite well until rpm get up above 17k or so. I have worked with quite a few guys with modified engines from many modifiers that were not happy with how engines ran with 257's when really wound up hard, suggesting switching to the 771 or 929 carb in all cases have made them happier.

Success speaks volumes

Thanks,

I've had problems with bogging on 2 engines, and just ordered these 2 carbs.

Even do I'm surprised that boat engines arent reving past 20k rpm.

Highest rpm I've got from G260RC engine was 24600rpm, and from 260 with reed case was 25500rpm.

Scott wrote:
Yes, with 257 carb versus 603 or 668 I got much better throttle response, but when the engine is on normal working temps, on the table it spins normally, but on the track it seems to bog when full throttle is pushed out of the turns, and none of the carb adjustments didnt help.