chop test question

[handleme46]

ok i understand the reasoning for the chop test, but i was just wondering if it would work while the bike is on a stand? i dont see why not other then maybe it has to be under a load? Im just trying to clear up if i should buy a br8eg for my CR125 or lean the pilot and go with a br9eg.

 

[bigred455]

The reason for checking your jetting in real conditions, consider this ,let's just say you are rich on your main or needle it revs so freely when on the stand because their is no load on the engine it revs very quickly to max rpms.Now if your bike is rich running up top, you will find that in true conditions with a load on the engine the rpms up top will not max out or be very slow about it,or break up or miss, or blubber. You see on the stand it will have no load on it so IT REVS OUT NO MATTER WHAT unless you are really rich.

 

[Rich Rohrich]

Regardless of engine speed, the air flow and fuel delivery demands of an engine depend on the load being placed upon it. That load and the resulting throttle opening directly effect manifold absolute pressure (MAP), which in turn affects the fuel requirements. Fuel requirements depend more than anything else on how much work you are asking the engine to do, basically how much of a load you are placing on it. MAP increases as load and power increase. It's not a coincidence that EFI equipped auto engines use MAP sensors to help determine injector pulse width (basically the EFI form of jetting).

In short, without setting the jetting with the appropriate load on the engine, you are only jetting for racing on the stand. :thumb:

 

[handleme46]

ok then i guess il scratch that idea an just do it the normal way. thanx for the info you guys are a great help