Carb settings??

[TKA-NZ]

Ive got a 97 SPX its got the 787 motor.

Im in the process of rebuilding the carbs and ive been doing some research on here about setting the Hi and low speed mixture screws.

I understand these can vary and be adjusted to tune the motor.

Is there a std setting these should be at??

I counted the screws out for each when I dismantled the carbs.

The front (mag) carb was - Hi 1/2 turn out and low 1 turn out.

The back (pto) carb was - Hi 1 screw out and low was basically screwed right in, possibly 1/4 turn out (depends how tight you screw it in).

Any help would be really appreciated.
Thanks

 

[dsw222]

your low speed screws should both be 1 and 1/4 turns

your high speed MAG screw should be zero, and your high speed PTO screw should be 1/4 turns

 

[TKA-NZ]

ok thought mine seemed to be a bit over the place.

Does screwing them out make it richer or leaner??

Seems strange that one of the Hi speed screws was 1 turn out and the other was 1/2 turn out as from what ive read even 1/4 of a turn makes quite a difference to air fuel mixtures.

 

[dsw222]

screwing in makes it leaner

was it running well with how it was set?

 

[TKA-NZ]

It was running fine until it started surging/losing power which gradually got worse.
Ive replaced fuel lines and cleaned carbs out etc.

Would i be best to reset screws to where they were??

 

[dsw222]

It was running fine until it started surging/losing power which gradually got worse.
Ive replaced fuel lines and cleaned carbs out etc.

Would i be best to reset screws to where they were??

If the ski is stock, then no use the stock settings

If there are modifications done to it, then list them

I dont know why a low speed would be turned all the way in, but it looks like someone turned out the high speed to make up for it... I would put it back to factory settings and see how it runs

Make sure you use the correct springs when you rebuild the carbs. Maybe someone didn't know what they were doing last rebuild, and used the wrong springs then tried to adjust for it by turning the screws

 

[TKA-NZ]

Just checked the rave valves and on of the didnt have a spring there. Could this effect performance or be the reason for the differing settings between carbs??

 

[dsw222]

Just checked the rave valves and on of the didnt have a spring there. Could this effect performance or be the reason for the differing settings between carbs??

Put a spring in that RAVE... it needs one.

Then set your carbs to factory spec