calivette2003

Went to El Capitan lake (San Diego CA) on Saturday.
Have a dead stock 91 650sx. Lower end has probably never been redone. The head looks to be recently rebuilt since it's powdercoat looks shiny and new compared to the lower end.
Only noticeable mods: a black pro plate and unknown SS impeller.

According to my Honda's GPS, the 650sx with a 225lb driver going into 12 knots of wind with wind ripples on the water got a best of 38mph.

This sound about right?

I did notice there was no speed increase or engine (sound) increase for the last 3/8" of throttle travel.
Re-checked the throttle cable connections and adjustment. The cable connection on the carb opens the butterfly from idle stop to throttle pinned wide open with the butterfly also wide open. Is that normal to have no increase in engine rpm for that last 3/8"'s of travel?

calivette2003

This is my baseline to decide whether I should mod the 650.

fedorov5549

Your pretty close but try to turn out the high speed screw 1/4 turn and try again. Best way is to tie it to something on shore while wide open in the water or adjust while riding. I've had a couple 650s and they are about 40 mph.

calivette2003

I want to be sure I adjust the right speed screw, is that the top speed screw?

calivette2003

Does anyone know which screw is the high speed screw?

fedorov5549

Top one the main, or high. Bottom one is the slow, or pilot.

calivette2003

Thanks, appreciate the info.