CrankDex

Yamaha RT1BM Spark Plug

The Yamaha RT1BM (250cc) takes an NGK BR8ES spark plug, gapped to 0.028".

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Key takeaways

  • Spark plug: NGK BR8ES.
  • Iridium upgrade: NGK BR9EIX.
  • Gap: 0.028 inch - set it before fitting.
  • Covers 1975-1976.
Standard PlugBR8ES
Iridium UpgradeBR9EIX
Gap0.028"
Verified fitLast checked
Sources: NGK powersports application catalogue
Reviewed by the CrankDex editorial team against manufacturer and retailer fitment data.

Buy the plugs for your Yamaha RT1BM

The standard plug is the exact-fit replacement. The iridium version drops into the same spot, lasts longer, and fires a little stronger for a few dollars more. Many engines take more than one - check how many cylinders you have.

Shop the BR8ES plugStandard NGK plug + multi-packsShop Upgrade: BR9EIX iridiumLonger life, stronger sparkShop

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Frequently asked

What spark plug does a Yamaha RT1BM take?

The Yamaha RT1BM takes an NGK BR8ES spark plug, gapped to 0.028 inch. The iridium upgrade is the BR9EIX.

What is the spark plug gap for a Yamaha RT1BM?

The spark plug gap for the Yamaha RT1BM is 0.028 inch. Check and set the gap before fitting a new plug - most powersports plugs need a small adjustment out of the box.

Can I use an iridium plug in a Yamaha RT1BM?

Yes. The BR9EIX is the iridium version of the BR8ES - same fit, longer life, and a slightly stronger spark. It is a straight upgrade.

More parts for your Yamaha RT1BM

We cover the other consumables for your machine too - the exact fit, cited, in one place.

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