W.O.T bog problem

[93notch408]

im having a problem with my drag bike its a built big block 95mm piston the works...has a 38mm flat slide mikuni on it when i pin it it bogs sputters and stuff like it wont go know where but if i roll back on the throttle to like 3/4 it starts pulling harder im stumped i cant figure it out im thinking lean but it has a 250 jet in it and i cant really get a plug reading cause im playing with the throttle so much lmk your input thx!

 

[Stangrcr1]

Need a bigger pilot jet.

 

[125ccCrazy]

Assuming the bog is at the bottom end? have you played with the needle setting? if not try dropping the clip a notch and see if it gets better or worse..

 

[Norcalputput]

If the problem is at WOT it's going to be the main jet the needle position will not have effect at WOT the needle is out of the jet at that point.
Do you have a way to place a load on the engine it could even just be the brakes on the rear tire as long as they are good
Place bike on some lumber with rear wheel in the air
Start engine bring to operating temp
Begin to rev the engine wile dragging the brake to provide load when you have reached WOT and you can hear/feel the bog hit the ignition kill and read the plug



Sent from my iPhone using Mores code

 

[125ccCrazy]

If the problem is at WOT it's going to be the main jet the needle position will not have effect at WOT the needle is out of the jet at that point.



Sent from my iPhone using Mores code

that is true..

Is it running good up to WOT and then bogging or is it bogging before reaching high end with the carb fully opened?

 

[Stangrcr1]

Read this.


You have to get it cleanly off idle with the pilot circuit before the needle and mains take over.