KTM 400 LC4 EXC Spark Plug
GarageDex's powersports data shows the KTM 400 LC4 EXC uses a BR9HS spark plug, gapped to 0.024", or upgrade to the BR9HIX iridium plug.
Spark plug fitment by year
| Years | Standard plug | Iridium upgrade | Gap |
|---|---|---|---|
| 1977 | BR9HS | BR9HIX | 0.024" |
350cc motorcycle. Match the exact part code, thread reach, and heat range. The iridium column is the same-fit upgrade for a longer service life.
Spark plugs for your KTM 400 LC4 EXC
The recommended plug is a BR9HS. Match that code - spark plugs are thread-, reach-, and heat-range-specific, so the part number matters more than the brand. Worth considering: the BR9HIX iridium upgrade - it fits the same port, fires cleaner, and lasts far longer between changes.
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Frequently asked
What spark plug does a KTM 400 LC4 EXC take?
GarageDex's powersports data shows the KTM 400 LC4 EXC uses a BR9HS spark plug, gapped to 0.024", or upgrade to the BR9HIX iridium plug.
What is the spark plug gap on a KTM 400 LC4 EXC?
The KTM 400 LC4 EXC spark plug gap is 0.024". Set the gap with a feeler gauge before install - iridium plugs come pre-gapped but always verify, since a wrong gap causes misfires and hard starts.
Are iridium spark plugs worth it on a KTM 400 LC4 EXC?
The BR9HIX is the iridium upgrade for the standard BR9HS. It fits the same port and heat range, fires more reliably, and lasts far longer between changes - a worthwhile swap for most riders, though the standard plug is perfectly fine if you change plugs on schedule.
How often should I change the spark plugs on a motorcycle?
Standard plugs typically want replacing every 8,000-12,000 miles (or per your service manual); iridium plugs go much longer. Fouled or worn plugs cause hard starts, misfires, and poor fuel economy - a cheap part that punches above its weight.