NGK BP6HS = Higher Compression?

Discussion in 'High Performance Bicycle Engine Tips and Motorized' started by onanysunday, Apr 23, 2011.

  1. Citi-sporter

    Citi-sporter Member

    Jun 16, 2014
    Likes Received:
    There seems to be some bit of misinformation in this thread about plug life in premixed, old school 2 cycle engine operation.

    These HT engines are definitely old school.

    If you consistently mix your fuel and quality oil ratio and pull and inspect and gap/clean the plug at service intervals you shouldn't need to change them very often.

    I had a 1960's Yamaha step-through 50 cc bike I regularly commuted to work on for 3 years, that I would get over 5k miles between plug changes running 32:1 mix. This was before E10 fuel, in the 1980's.
    I'd change the plug at that period even though it really didn't need much more than checking the gap and a wire brushing. It probably would have ran for 10K before it really carbon fouled. I'd pull the head and scraped carbon off the piston and head at 10k intervals on that bike.

    There's really little more you an do for these if you're not racing or otherwise running them beyond their recommended use. These engines were originally designed to power heavy old Flying Pigeon single speed bicycles as commuter powerplants in PRC before they became popular here in the US.

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