Jetting notes - CRF150R

[Rich Rohrich]

The CRF150R uses a 32mm version of the Keihn FCR carb.
The service manual lists the stock CRF150R jetting as :

Main jet : 135
Pilot jet : 40
Needle : NHNT (3rd position from top)
Pilot screw 2 1/4 turns out
Idle speed 2100rpm + or - 100 rpm
Float level 7.0mm

Initial feedback is the pilot is a bit on the lean side, which is pretty common from Honda. A 45 pilot and some fine tuning on the pilot screw should do wonders, just like on the big CRFs.

 

[DMedeiros]

Rich- I am new at this racing fourstroke tuning thing. You post idle speed at 2100rpm. Do all racing four strokes require high idle speeds.
My son rides Hare Scrambles and is having a hard time keeping his 150R running in tight woods. Maybe were the idle is set is the reason why. Any input will be greatly appreciated.

Thanks
A strung out father
DM

 

[Rich Rohrich]

Rich- I am new at this racing fourstroke tuning thing. You post idle speed at 2100rpm. Do all racing four strokes require high idle speeds.

Racing four-strokes tend to run a lot of cam overlap and minimal flywheel weight so a high idle speed is usually necessary. Even a big engine with a lot of crankshaft mass like the YZ400F needed an 1800-2000 rpm idle speed.

 

[HajiWasAPunk]

Rich, Honda always gives the impression from their owner's manual that the stock jetting is perfect for FL conditions. Yet nearly everyone I've talked to talks about making the changes you mentioned above, particularly on the 150. What's the deal, why don't they just ship that way? I guess it's a matter of opinion but having bikes that don't easily stall in tight corners seems like something everyone would like (if I wanted to fan the clutch I'd be on a 2-stroke right!). Or am I missing something?

 

[Jasle]

Rich, Honda always gives the impression from their owner's manual that the stock jetting is perfect for FL conditions. Yet nearly everyone I've talked to talks about making the changes you mentioned above, particularly on the 150. What's the deal, why don't they just ship that way? I guess it's a matter of opinion but having bikes that don't easily stall in tight corners seems like something everyone would like (if I wanted to fan the clutch I'd be on a 2-stroke right!). Or am I missing something?

Gotta pass emission standards in stock trim. after you get it all bets are off.