The NGK D8HA is the factory-correct spark plug for the CB175, CL175, and SL175. A fouled or worn plug shows up as a misfire, hard starting, or a cylinder that won't pull its weight. Fresh plugs give your ignition a clean, hot spark to work with.
The D8HA is the correct heat range for these engines: hot enough to burn off deposits, not so hot it pre-ignites. Run a plug that's too cold and it fouls with carbon; too hot and it can pre-ignite. The copper-core construction gives a reliable spark and a long service life.
The CB175 family is a parallel twin, so you need two plugs, one per cylinder. When you're chasing a carb jetting issue, grab a few extra and read the porcelain tip color to dial in the mixture.
Note: The CB200 and CL200 are based on the CB175 but use a different spark plug, the NGK D8EA. Don't substitute the D8HA on a CB200 or CL200.
Difficulty: Beginner
Tools needed: 18 mm spark plug socket, gap gauge
Our short video explains the terminal nut versus terminal stud, so your plug cap seats the way it should.
The NGK D8HA. It's the factory-correct heat range for these engines, and you need two, one per cylinder.
0.024–0.028" (0.6–0.7 mm). Set it by bending the outer ground electrode. Don't confuse it with the contact-point gap, which is a smaller measurement.
No. The CB200 and CL200 are based on the CB175 but take the NGK D8EA, not the D8HA.
Pull the plug and look at the porcelain around the center electrode. A light tan or brown color is healthy. Sooty black means the mixture is running rich; chalky white means it's running lean or too hot.
Last updated: June 2026
