I bought the BSP replacement carb for the predator with a 36 jet and gx140 tube too. I set it at 2 turns when I put it on and have been meaning to play with it. Not sure if it's idling weird because of the cam or it just needs to be adjusted a bit.
What's a good RPM for a modded Predator to idle at anyway?
What's a good RPM for a modded Predator to idle at anyway?
Yup.
They generaly will not sit there and idle too well when you put an aftermarket cam and up the compression.
Nothing I have ever really idled in the first place.
I got used to the idea of tapping the throttle and keeping it burbing and farting that way.
My logic was and remains I want the shutter closed as much as possible so under a high vac sittuation ( coast down ) where I am likely to snap the throttle back open I will have extra fuel.
The high vac pulls harder on the low side that normal and delivers a much richer mixture than normal
This compensates for the big carb lean out problem ( somewhat ).
Cams play havock with this.
The right combination of durration with flow in the intake and exhaust causes the carb to fog or spit up.
Reversion is a word that I hear tossed around to explain this.
Since I have no way to measure it I except that under some conditions ( screw up in the build and generaly at low rpm) the cylinder presure may be high than in the intake manifold and can push a fresh charge back out the carb.
Changing things like the exhaust and air filter/ adaptor, intake length or compression can help work around this problem but its hard to make it go away...
Its a miss match...
Less cam Usually works, but then you change everything around and maybe miss your mark for your desired power.
Dropping cmpression sometimes help, sometimes raising it is the solution too.
Things got to work together as part of a plan.
Can grinder usualy has sugestions and ranges of compression and carb you shoudl stay within.
They generaly will not sit there and idle too well when you put an aftermarket cam and up the compression.
Nothing I have ever really idled in the first place.
I got used to the idea of tapping the throttle and keeping it burbing and farting that way.
My logic was and remains I want the shutter closed as much as possible so under a high vac sittuation ( coast down ) where I am likely to snap the throttle back open I will have extra fuel.
The high vac pulls harder on the low side that normal and delivers a much richer mixture than normal
This compensates for the big carb lean out problem ( somewhat ).
Cams play havock with this.
The right combination of durration with flow in the intake and exhaust causes the carb to fog or spit up.
Reversion is a word that I hear tossed around to explain this.
Since I have no way to measure it I except that under some conditions ( screw up in the build and generaly at low rpm) the cylinder presure may be high than in the intake manifold and can push a fresh charge back out the carb.
Changing things like the exhaust and air filter/ adaptor, intake length or compression can help work around this problem but its hard to make it go away...
Its a miss match...
Less cam Usually works, but then you change everything around and maybe miss your mark for your desired power.
Dropping cmpression sometimes help, sometimes raising it is the solution too.
Things got to work together as part of a plan.
Can grinder usualy has sugestions and ranges of compression and carb you shoudl stay within.
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