Originally posted by Brett.w
Thanks for your advise do you have one of these and what are your carb settings?
Hope these comments come in handy for you. Got them at Trinity's web site, and I think they are a very clear carb tuning guide.
All carburetors are factory set on a flow bench. For this reason it is recommended that you count the number of turns on the low and high end needles before you use the engine. All carbs are not the same, but are set to flow the same amount of air and fuel. Up to a one half turn difference can be had on factory carburetor settings on each needle. A two micron difference in the needle taper can make the setting up to 1/2 turn different from another carb. It is also not recommended not to adjust the mid-range needle setting on until you are completely comfortable with carburetor adjustment.
How big is a micron? There are 25,400 microns in one inch. This dot (.) is approximately 1/64 of an inch wide and equals 615 microns. It doesn't take much to off set a needle setting.
Novarossi based engines (General Carb Settings)
Low Speed: 3.25 turns out
High Speed: 4.75 turns out
Mid-Range: Flush with the carb body
What is the "Top End" needle?
The "Top End" needle is the large needle valve that adjust how much fuel is delivered to the engine from half throttle to full throttle.
What is the "Bottom End or Low end" needle?
This needle adjusts how much fuel the motor gets at idle and at the first crack of the throttle.
What does is mean when people say my motor is "too rich?"
This means that there is too much fuel being supplies and not all of it is being burned off in the combustion cycle.
What does it mean when people say my motor is "too lean?"
This means that the motor is not getting enough fuel. This can make a motor difficult to start or make it run too hot.
How do I know if my motor is "too lean?"
A motor that is too "lean" will not stay running. Usually will flame out at full throttle or not idle. Temperature is one way to check this. Another way is to examine the plug. The element in the plug will turn close to "white" and be dry if the motor is too lean. This condition is very damaging to the motor since the motor relies on fuel for it's oil supply as well.
How do I know if my motor is "too rich?"
A motor that is too "rich" will spit raw fuel out of the exhaust pipe and never really reach top RPM or "clear out" meaning to not burn all the fuel. This motor will usually idle OK but will bog and die the second the throttle is applied if the low end is "rich" or never reach full RPM is the "top end" is rich.
What does it mean when people say I have to adjust the "bottom end?"
This means you need to adjust the low-speed setting on the carburetor.
How do I adjust the idle?
The idle is adjusted by turning the idle screw on the carburetor. This can be found by looking at the manual that came with the motor. Turning the screw in will increase the idle speed and turning the screw out will decrease the idle speed. These screws are simply a stop for the slide or barrel of the carburetor.
Why does my car die after only idling for a few seconds?
This usually means the low-speed needle (i.e. bottom end) is too lean. Try turning the low speed needle out (counter clockwise) about 1/8 of a turn at a time until the car will idle.
Why does my car die right after I accelerate from a stop?
This again is usually a lean condition on the "bottom end." Try "richening" up the low-speed needle by turning it out 1/8 of a turn at a time until this condition stops.
How far should I turn the needle valve when I make adjustments?
Any needle valve should only be adjusted in 1/8 turn increments. These are very sensitive adjustments.
Are there "starting" points for my needle valve settings?
Always follow the manufacture's recommendations.
How would I know if I have an air leak in my carburetor?
This is a tough one. An air leak will make the motor very very difficult to tune. Usually the idle will be inconsistent and the motor will generally not want to perform consistently. This is a difficult condition to detect.
When I rev my car it seems to idle at a higher RPM for a few seconds then settle down. Why?
This could be from an small air leak in the carb, or from a motor that is running a bit too lean.
What type of oil should I use on my foam air filter?
We suggest any "tacky" petroleum based oil. Motorcycle shops sell this for ATV's and dirt bikes air cleaners. Don not use silicone based oils. K&N air filter oil is specifically made for K&N filters and is not good for use on foam filters.
How do I read my plug?
Actually when a new plug wire just goes slightly gray after a 5 or 10 minute hard run, it means your very close to an optimal horsepower tune, but be careful the next step is TOO LEAN!
Rule of thumb:
1} Wire and surrounding bottom of plug wet, with like new shiny wire = rich side of optimum power 85%
2} Wire and surrounding bottom of plug starting to dry and wire starting to gray = Very close to optimum power 95%
3} Wire and surrounding bottom of plug dry, wire totally gray but not distorted optimum power 100%
4} Wire and surrounding bottom of plug dry, wire distorted = slightly lean DANGER!
5} Wire and surrounding bottom of plug dry, wire broken and distorted or burnt up = extremely lean possible engine damage!
Note: You can only "Read" your plug in a nearly new state [Wire like new and shiny] A gray plug can still operate well, but after it has totally gone gray performance can start to fall off. To test just put in a new plug and if there is no difference in performance save the gray one or put it back in. If your engine does not feel or run right try a new plug before making major tune change's