How hot is hot?

[Texas001]

Originally Posted by seahunter

The correct plug for that motor is the NGK-BP5HS. The ES your using is an automotive plug. It extends 1/4" further into the combustion chamber than specified.

I certainly was confused as to which was the correct plug. I used this site to find the NGK plugs and they listed several.


I will pull these plugs and install the BP5HS before the piston hits the tip of the plug. Thanks for giving me the correct plug.

[Texas001]

Originally Posted by seahunter

The correct plug for that motor is the NGK-BP5HS. The ES your using is an automotive plug. It extends 1/4" further into the combustion chamber than specified.

Bought and installed the BP5HS today. Just have to wait until the weather warms a bit to do a test run and see if the other plugs were too hot. Did a idle mod today and I am not sure that I like it. Probably need to do more testing before I commit one way or the other. Mod was basically simple but there is more to it than the instructions imply.

[Texas001]

Originally Posted by seahunter

The correct plug for that motor is the NGK-BP5HS. The ES your using is an automotive plug. It extends 1/4" further into the combustion chamber than specified.

Since I have a 4 stroke I am not sure this IS the correct plug. Everything I see says BP5HS is for a 2 stroke. They don't seem to preform correctly in my 4 stroke. ????

[Texas001]

Originally Posted by seahunter

The correct plug for that motor is the NGK-BP5HS. The ES your using is an automotive plug. It extends 1/4" further into the combustion chamber than specified.

I found the plugs here that identify the correct plug by 2 and 4 cycle engines. I have a 4 cycle.

[seahunter]

Originally Posted by Texas001

I found the plugs here that identify the correct plug by 2 and 4 cycle engines. I have a 4 cycle.

Sorry, didn't catch that before. I run 2 cycles

[BLUE72CAMARO]

I was just looking for this informatioin yesterday for my new motor and the ezgo manual calls for a bpr4es. Should I go up or down in temperature for an engine with bumped up compression?

[Texas001]

Originally Posted by BLUE72CAMARO

I was just looking for this informatioin yesterday for my new motor and the ezgo manual calls for a bpr4es. Should I go up or down in temperature for an engine with bumped up compression?

I found this when doing some research on plugs:


Heat Range See: http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml

for an idea about heat range



Controlling the operating temperature of the plug’s firing tip is the single most important factor in spark plug design. “Heat range” is the relative temperature of the spark plug’s core nose, and it is determined by the length and diameter of the insulator tip, as well as the ability of the plug to transfer heat into the cooling system. A “cold” plug transfers heat rapidly from its firing end into the cooling system and is used to avoid core nose heat saturation where combustion-chamber or cylinder-head temperatures are relatively high. A “hot” plug has a slower heat transfer rate and is used to avoid fouling under relatively low chamber or head temperatures. What’s confusing is that a “hotter” (higher performance level) engine requires a colder plug because more power equals higher cylinder temperatures.

Critical factors affecting heat range include:

• Air/fuel mixture: Lean air/fuel ratios raise cylinder-head temperatures, requiring a colder plug. Rich air/fuel ratios require a hotter plug to prevent fouling. Mixtures that cause the plugs to read lean may contribute to pre-ignition or detonation. If not running an electronic engine management system, it pays to tune slightly on the rich side to avoid detonation.

• Spark advance: Ignition timing has one of the greatest effects on plug temperatures. It becomes more critical as compression ratios increase. More timing raises combustion temperatures, calling for colder plugs.

• Compression ratio: Increasing the mechanical compression ratio raises cylinder pressure, resulting in higher cylinder temperature. The higher the compression ratio, the colder the spark plug needs to be. According to Champion Spark Plugs, for normally aspirated, gasoline-fueled engines, a good rule of thumb is to go about one heat range colder for each full point in compression ratio increase from 9:1 through about 12.5:1, and two heat ranges colder for each point increase between 12.5:1 and 14.5:1. Beyond 14.5:1, 3-4 heat range reductions per point may be needed.

Now comparing a car engine to a golf cart engine is quite the conundrum. But at least this give you a start.