Bocchi the Biker's Life 気まぐれバイク旅
Is your engine acting up lately?
If your bike feels sluggish or doesn’t start smoothly, worn-out spark plugs might be the culprit. In this post, we’ll walk you through how to replace the spark plug on the Suzuki Grasstracker 250—with photos and tips perfect for beginners or first-time DIY mechanics.
When Should You Replace the Spark Plug?
One day I asked myself, “When was the last time I changed my plug…?”
After checking my maintenance log, I realized it had been over 20,000 km—way overdue!
For most motorcycles, it’s recommended to replace spark plugs every 3,000–5,000 km.
Realizing the urgency, I quickly ordered a new one from Amazon. It only cost ¥340—hard to believe I waited this long for such a cheap fix!
Tools & Parts You’ll Need
Replacement Plug
- OEM plug: NGK DR8EA（7162）
- Optional upgrade (Iridium): NGK DR8EIX
I went with the cost-effective standard DR8EA.
日本特殊陶業(NGK) 一般プラグ (ネジ形/ターミナルなし) 1本 【7162】 DR8EA
Tools
- Plug wrench (18mm): Usually included in your bike’s toolkit
- Screwdriver: Used to turn the wrench during removal
Step-by-Step Spark Plug Replacement
① Remove the Spark Plug Cap
Grip the cap and twist gently while pulling to remove it. No tools needed.
② Unscrew the Old Plug
Insert the wrench, then use the screwdriver to rotate it counterclockwise and pull out the old plug.
Comparison photo: The new standard plug vs. the worn-out iridium plug. While iridium plugs offer performance benefits, the standard plug is more than sufficient for city riding.
③ Install the New Plug
Hand-tighten the new plug until it seats firmly against the cylinder head.
Tightening guideline:
Torque: 15–20 N·m (1.5–2.0 kgf·m) Or: 1/2 turn (180°) after seating
I chose the 1/2 turn method, rotating the wrench 90° twice for precision. Avoid over-tightening or loosening once fitted—it can mess up the torque.
If your tools don’t fit due to the gas tank, you can remove the seat and loosen the two tank bolts to raise the tank slightly and create room.
④ Reattach the Plug Cap & Start the Engine
Push the cap back into place and test the engine. If it starts smoothly, you’re done!
After the Replacement – What I Noticed
Right after the replacement, I immediately felt a boost in torque.
Until then, my bike struggled going uphill unless I downshifted, and I had assumed it was just aging or engine wear.
Turns out—it was just a worn spark plug all along!
With the fresh plug, my Grasstracker 250 regained its natural power and smooth ride.
It’s amazing how such a small and inexpensive part can revitalize your engine.
Spark plugs are affordable, easy to replace, and offer noticeable results.
That makes them a perfect first step into DIY motorcycle maintenance.
If your bike’s performance feels off or less responsive, checking the spark plug is a smart and simple place to start.
Summary
- Spark plugs are consumable parts—don’t wait until your bike feels sluggish to check them.
- For the Grasstracker 250, replacement takes about 30 minutes with just a few basic tools.
- You’ll likely feel an immediate improvement after installation—and enjoy a real sense of accomplishment from doing it yourself.
