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Yahoo Bid Automotive Motorcycles Auto Parts Ignition Yamaha
RZ250 RZ350 点火 プラグ インデクシング スペーサー 1気筒分 RZ250R RZ350R 29L 31K 51L 1XG 3HM TZR250 2XT 1KT R1-Z 4L3 4UO TDR250
 
        

写真2気筒分ですが本セットは1気筒分です

  • Product Quantity
    : 1
  • Starting Bid
    :1,100円
  • Highest Bidder
    : / Rating:
  • Listing Date
    :May 23, 2026 20:42
  • Bidding closes on
    :May 30, 2026 20:42
  • Auction Number
    :v1187837754
  • Condition
    :New product
  • Automatic Extension
    :No
  • Authentication
    :No
  • Early Closing
    :Yes
  • Can I return the product?
    :no
  • Description
  • Q&A ()
  • Cost Estimator
  • Problem Item Response Procedur
点火プラグ インデクシング スペーサー 

点火プラグ インデクシングに使うスペーサー。1気筒分をセットにしました。
2気筒分が欲しい方は2つ落札してください。

NGK型番で言うBタイプ用です。
B8ESとかBR8ESなどのネジ径に合わせています。

いわゆるライトチューン、お手軽チューンです。
インデクシングと通称されますが、参考画像にあるような点火プラグの向きを揃えてやることです。

クルマではH社でも研究されたということですし、T社では実際に市販車でもこうしたケアが行われていると聞きます。

T社ではヘッドプラグ穴のネジの切りはじめと、プラグのネジの切りはじめ位置を合わせることで電極の方向を揃えているんだそう。

F1などでもこの電極の向きはこだわるんだそうですね。

レポートを見ると4ストロークだと吸気バルブ側に点火プラグの開口部を向けてやるということが多いようです。
こうすることで吸入した新気に対してスパークがあたりやすくなるんだとか。

これは2ストロークでも有効な手法でして、排気ポートに対して垂直方向に電極を向けるのが良いとされています。
参考1の画像のような感じですね。

当方の実験でも、排気ポートに対して垂直方向に電極を向けるとエンジンが滑らかに回るようになる。
プラグ電極の開口部は排気方向でも吸気方向でも大差なく感じるのですけれどね。

しかし、排気ポートに対して電極開口部を90度に向けてしまうとどうもアイドリングのばらつきなどが大きくなる。
参考2の画像のような形ですが、これがあまりいい印象が持てない。
個人的な考察では点火のしやすさというより、排気の際に横向きになった電極が流れの邪魔になるのかな?という印象を持っています。

長年、当り前のようにこれを実践してきましたが、どうも世間ではそうでもないようで。
スペーサーも入手しづらいので、ご用意してみました。

材質:スチール
厚みは 0.1mm、0.2mm、0.3mm、0.5mm各1枚。

Bタイプのプラグはスペーサー0.2mmでだいたい60度回転します。0.1mmで30度です。
これ以下の微調整は締め具合で調整できます。

セッティングとしては以下のようにするといいでしょう。

1.電極の開口方向にこだわるより、電極の向きを排気ポートに対して垂直にすること。

2.左右シリンダーのプラグ開口方向はそろえること。つまりキャブ方向に向けるか排気ポートに向けるか。これは合わせること。

スペーサーを重ねればその分圧縮を低下させますし、プラグ電極が引っ込む分スパークが混合気にあたりづらくなる。
なので、開口部を絶対キャブ側にしなきゃ…と考えると弊害が出やすいのです。
1回転分だと1.25mmもプラグが浮くので、せいぜい半回転分の調整に抑えたほうがいいと思います。
だから電極開口部はキャブ側でそろえるか、排気ポート側でそろえるかのどちらかにすればよいでしょう。

ちなみに、プラグは一度装着してワッシャをつぶしてからスペーサーを入れて再装着してください。
プラグにはマジックなどで電極の向きがわかるようにマーキングしておくといいです。



旧車向けカスタムパーツです。ノークレームノーリターンでお願いします。
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Please confirm and inspect the product as soon as possible to ensure that the product specifications, quantity, accessories, and description are correct

If, unfortunately, there are any issues, you can refer to the following examples on how to report related product problems:
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4. Due to 99% of Japanese sellers being unwilling or unaware of shipping goods overseas, if a seller is willing to handle the issue, the goods must be sent back to Japan, and the international shipping costs incurred must be borne by the member. Letao will use postal EMS international express to send the goods back to Japan.
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1. Issue of Authenticity: If antique or branded goods are found to be counterfeit upon receipt, clear photos showing the differences between the genuine product and the imitation must be provided as evidence. If unable to provide relevant proof, assistance can be sought to find a third-party reputable organization for a premium authentication service .
2. Leaking Iron Teapot: If an antique iron teapot is leaking, please take clear photos of the leaking area and provide them.
3. Transport Damage: If the goods are damaged during international shipping (to the pickup point), you need to provide photos of the outer packaging of the parcel and clear photos of the damaged goods' outer packaging.

※ Note: Photos provided to sellers should not contain any foreign-related information.
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    Product name: RZ250 RZ350 点火 プラグ インデクシング スペーサー 1気筒分 RZ250R RZ350R 29L 31K 51L 1XG 3HM TZR250 2XT 1KT R1-Z 4L3 4UO TDR250
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