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harley davidson spark plugs

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A small market ($78K/yr) — this niche doesn't clear our bar today.

Market size 19Growth 64Conversion 65Competition 22Returns 82Price range 74Avg price 85Brand share 19Review moat 72Quality gap 45

Avg price

Great$18.88

avg listing price — sweet spot $15–$100

Returns

Great1.7%

return rate — above 6% kills the launch gate

Price range

Good$6.55–$38.94

cheapest to priciest tracked listing — scored on the share inside $15–$100

Review moat

Good612.07

avg incumbent reviews — the moat a new listing must climb

Conversion

Good5.8%

search→purchase rate — share of searches ending in a sale

Growth

Good+42.4%

90-day search growth — must beat 0% to launch

Quality gap

Okay4.5★

avg incumbent rating — lower means beatable quality

Competition

Bad73%

top-5 click share — a locked-up shelf

Market size

Bad$78K

$78K/yr · 71K searches

Brand share

Bad93%

top-5 brand share — brand-locked demand

Competition

The top 5 products capture 73% of clicks — a locked-up shelf that new listings rarely crack.

Brands

8 falling

Sellers

51

Top-5 brand share

93%

Open market

4%

  • NGK71%
  • V-Twin9%
  • TORCH5%
  • CNPAPC4%
  • Motoforti4%
  • Atesilor3%
  • Open — no brand owns it (2 brands, 4%)

Product shelf

Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.

0%10%$8K20%$16K30%$23K40%$31K101001K10K Reviews — right = deep review moat Market share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)

All 14 tracked products in this niche — three views at once, no toggling.

Demand

Weekly Amazon search volume, last 40 weeks — +42.4% search growth over the last 90 days.
2K1KSpike '26Oct '25Nov '25Dec '25Feb '26Mar '26May '26Jun '26

Reviews

What buyers praise and complain about, mined from review topics.

What buyers love

Quality-Overall23%

“Quality Products”

Socket/Port/Plug18%

“Plugs great”

Value For Money17%

“Excellent price”

Size-Overall15%

“good fit”

Advertised Vs Actual Product12%

“Works as it should”

Efficiency7%

“Did the job”

Durability3%

“040 so it's good to know these are as durable as they're advertised to be”

Ease Of Use1%

“Ease of use”

Assembly/Installation1%

“they where easy to install yes you do need to gap them”

What buyers complain about

Advertised Vs Actual Product25%

“not listed right”

Size-Overall13%

“The longer wire was a bit long”

Compatibility-Overall13%

“Not compatible with older Harley models that it ought to fit”

Quality-Overall13%

“why not make a good product”

Socket/Port/Plug13%

“The plug end that goes in the solenoid is too small”

Top return reasons

Size-Overall54%
Compatibility-Overall15%
Socket/Port/Plug7%
Advertised Vs Actual Product5%
Defective Material/Parts5%
Value For Money3%
Product Condition3%
Functionality-Overall2%
Color2%
Quality-Overall1%