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Bigger cams runs richer

  • Thread starter Thread starter gearhead13
  • Start date Start date
gearhead13 said:
When I put the jets in I pulled the bowls and rechecked my float height. I really dont know unless my floats are not floating as much as they should. I turned the carbs on their side and tried blowing into the fuel line and the fuel valves seal well.
A gas leak from where to where? If the bowls filled too much it would just go out the overflow.
The acc pump is totally disabled as well.
Click to expand...

No idea as I'm not familiar with the RS. It is just a theory that fits your observations and explains why you are not burning holes in pistons.

Related but a little out of left field. I have a 1980 Dodge motorhome with a 440 engine and Carter Thermo Quad. Despite all attempts to regulate the idle mixture it is running rich. Mechanic suspect some type of leak.
 
gearhead13 said:
Well, I am really confused. My log files show the rpm maxing out intermittently, mostly at high rpm. I am wondering if my non-suppression wires are messing with the innovate stuff or my rev limiter.
I didnt have any mikuni jets smaller than 125 so I put in DJ 124 (about 116 mikuni) and not much change in A/F.
Maybe its ignition related.
Click to expand...

Where is the fuel screw? The fuel screw should not be turned out more than 1 turn max. It should be about a 1/2 turn out. Are the little rubber washers and the spring and metal washer at the end of the fuel screw in good shape and in the right order? What notch clip is the needle on? If your needing a main jet smaller than a 125 with 38mm RS Mukuni carbs you have a problem somewhere else in the carbs. Check the choke circuit make sure it is not leaking and the fuel screw will affect the entire throttle range. if it is leaking fuel into the intake track it could be your problem. Double check you float height also. With the cam change you should not have had to change the main jet by more than one size.
 
stetracer said:
Where is the fuel screw? The fuel screw should not be turned out more than 1 turn max. It should be about a 1/2 turn out. Are the little rubber washers and the spring and metal washer at the end of the fuel screw in good shape and in the right order? What notch clip is the needle on? If your needing a main jet smaller than a 125 with 38mm RS Mukuni carbs you have a problem somewhere else in the carbs. Check the choke circuit make sure it is not leaking and the fuel screw will affect the entire throttle range. if it is leaking fuel into the intake track it could be your problem. Double check you float height also. With the cam change you should not have had to change the main jet by more than one size.
Click to expand...
The fuel screw is at 1/2 turn and I put in new o-rings. spring, washer then o-ring, right?
Needle is on bottom notch, full rich, I tried other settings runs better there. The choke plungers seem to move properly, I want to take a second look to see if they are fully seating.
I noticed that the carbs were not level when on the bike, angled down at the back, so I repositioned the boots so they are level.
I put in a set of d8ea plugs and it runs better.
A/F still shows rich at WOT, I am going to recalibrate the O2 sensor.
 
Was reading some mikuni tuning guides and it said float height at 19mm +/-2mm
So, at 11pm I went down and reset my float to 21mm. I also took apart my choke assy. Someone had put the balls and springs in wrong, so the choke wasnt being positively held shut when pushed in, now it snaps shut good. Put the 125 mains back in and went for a ride. A/F looks better. It was rainy so I couldn't open it up and test it like I wanted to, looks better though. Wow a glimmer of hope and I was about to torch it or push it off a cliff.
One thing I have noticed about these carbs is that when I remove the first bowl drain, it drains for a long time, then the other three hardly have any in them, I think the tube connecting the bowls on the bottom for the A/P connects the bowls together not just for the A/P:confused:
I think the next sensor I want to setup is a temp sensor, so I can compare A/F reading with engine temp.
 
akckhim said:
Here's the reason more air flow pulls more fuel through the jet making it rich. Had head ported on drag bike years ago same thing had to drop one size on main jet gained .5 second and picked up 10mph.
Click to expand...

Yes, that is quite common.
 
Big engine small jet , small engine big jet. Rick Ward told me this back in the his Byron days.:)
 
Well, I have a 125 mikuni main with floats at 19mm now and it seems decent. My logging hardware isnt working properly but feels good. Plugs look good.
 
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