Engine Trouble Best spark plug for a YD100

[Guest_5]

I’m having trouble starting my YD100 and I was wondering if I needed a new spark plug, I was thinking if a E3 #32 plug would be good, I heard that the E3 #12 is no good because it hits your piston, but if there are any other ones that are better let me know!

 

[weefek]

Search search search.... read read read... It's not a mystery the NGK BR8HS , BR7HS, BR6HS are the preferred spark plug for these engines... There are some shorties out there but I haven't tried any of them yet ( I do have one but haven't tried it yet, no reason to, I have like 8 BR8HSs)

 

[Guest_5]

Search search search.... read read read... It's not a mystery the NGK BR8HS , BR7HS, BR6HS are the preferred spark plug for these engines... There are some shorties out there but I haven't tried any of them yet ( I do have one but haven't tried it yet, no reason to, I have like 8 BR8HSs)

Ok thankyou!

 

[motoredjosh]

im a little further south pretty hot with this recent heat wave i would try a b8hs but autozone doesnt carry the 8 so i got a b7hs instead, it runs fine no over heating

 

[Guest_5]

Interesting, I can’t even start my bike but I’ll grab one from the nearest auto zone by me and let you know

 

[ImpulseRocket]

The "Shorty" Plugs that were mentioned are basically the same plugs that Stihl chainsaws use. I run one in my Phantom 85 they are NGK BPMR7A plugs and the threaded body on them is about 1/8" shorter than the B8HS style plug.

I actually like the shorter style plug because the B8HS plug threads protrude into my combustion chamber quite a bit which makes for potential hot spot problems and the BPMR7A plug threads sit flush when tightened down. To make up or the shorter threaded body the BPMR7A has a projected electrode that pushes the electrode ends further into the cylinder to expose them to the charge better. Projected electrodes do also behave as a slightly hotter plug for their given heat range than a non-projected plug so keep that in mind.

The one downside to the shorter style saw plugs is that the end does not unscrew. This means if your plug cap needs that end to come off it will not work and you would need to install a different plug boot on your spark plug wire.

 

[Guest_5]

The "Shorty" Plugs that were mentioned are basically the same plugs that Stihl chainsaws use. I run one in my Phantom 85 they are NGK BPMR7A plugs and the threaded body on them is about 1/8" shorter than the B8HS style plug.

I actually like the shorter style plug because the B8HS plug threads protrude into my combustion chamber quite a bit which makes for potential hot spot problems and the BPMR7A plug threads sit flush when tightened down. To make up or the shorter threaded body the BPMR7A has a projected electrode that pushes the electrode ends further into the cylinder to expose them to the charge better. Projected electrodes do also behave as a slightly hotter plug for their given heat range than a non-projected plug so keep that in mind.

The one downside to the shorter style saw plugs is that the end does not unscrew. This means if your plug cap needs that end to come off it will not work and you would need to install a different plug boot on your spark plug wire.

Thats an interesting thing that I didn’t know, I’ll look into it because my spark plug isn’t creating a strong enough spark for my motor to run, so really anything thats strong then I’ll use that but I don’t like the idea of the spark plug protruding into my combustion chamber by how much you had mentioned.

 

[ImpulseRocket]

im a little further south pretty hot with this recent heat wave i would try a b8hs but autozone doesnt carry the 8 so i got a b7hs instead, it runs fine no over heating

This is a common misconception in the motorized bike world. Changing the spark plug heat range to a "hotter" plug does not change how hot the engine runs. I will spare you all the mumbo jumbo but the simplest explanation is that the plugs operate their best in a given thermal range and the heat range for a given motor is selected based on that range. Too cold and the plug cannot self clean and fouls easily. Too hot and it can fail to allow spark to fire from too high of a resistance AND potentially cause pre-ignition.

If you want to understand it better then this is a great simple explanation. https://www.denso.com/global/en/pro...e-parts-and-accessories/plug/basic/heatrange/

 

[ImpulseRocket]

Thats an interesting thing that I didn’t know, I’ll look into it because my spark plug isn’t creating a strong enough spark for my motor to run, so really anything thats strong then I’ll use that but I don’t like the idea of the spark plug protruding into my combustion chamber by how much you had mentioned.

The key thing to look at is how deep the plug threads are on the head. My Phantom cylinder is basically a modified copy of a Stihl MS460 cylinder so the threads in the head of it are identical to my MS460 Saw which is why the plugs that saw uses also work well on it. You can easily measure the depth of the spark plug threads and compare it to your plug. Also make sure that your plug gap isn't too wide. I run a gap of .02 to .025" and no greater

 

[Guest_5]

The key thing to look at is how deep the plug threads are on the head. My Phantom cylinder is basically a modified copy of a Stihl MS460 cylinder so the threads in the head of it are identical to my MS460 Saw which is why the plugs that saw uses also work well on it. You can easily measure the depth of the spark plug threads and compare it to your plug.

I have a YD100 so If I want to check the depth I have to take it all apart which I’m feeling a bit lazy for but I’ll come around.