Fellow Opti-2 users please help me out!

Discussion in 'Motorized Bicycle General Discussion' started by fischer550, Aug 4, 2014.

  1. fischer550

    fischer550 Member

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    It's about spark plug color. I live at 5,000ft above sea level. Just got a genuine dellorto 16.16. To make my motor run good, I put in a .58 dellorto jet. This made the motor run real nice, just a tiny tiny bit of 4-stroking at very little throttle, but other than that smooth sailing. Attached are photos of my spark plug (B6HS) next to a brand new plug after a 10 mile ride, no plug chop just regular riding at about half throttle for the most part. Before I switched to the B6HS, I went on a 20 mile ride using a B8HS and a .62 jet. The .62 jet made the engine 4 stroke up until about half throttle. When I checked the plug after that ride, the plug looked pretty much the same as the pictures below which confuses me. I love how my motor is running now, but I am scared that my motor is running too lean based on the pics. Please let me know what you think.

    Spark plug on left is the plug I'm concerned with, the one on the right is just a new one for comparison. I believe the last photo the plug looks a bit darker than it is due to lighting, but the first 3 look pretty accurate.
     

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    #1 fischer550, Aug 4, 2014
    Last edited: Aug 4, 2014
  2. Davezilla

    Davezilla New Member

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    That's not too bad considering you're running a lot more gasoline in your mix, you want that light tan color like the same way a 4 stroke engine would be when tuned properly. The third picture looks ok to me considering the mix ratio and the amount of time on that spark plug.
    The best and most accurate way to determine what your engine is doing would be to use a cylinder head temp gauge, these have a small washer shaped sensor that goes under the spark plug and they're very accurate, then you'd always be able to know if you're getting too hot. These engines will tend to produce a tinny sound and lose power when they get too hot as well, but that looks about right for running the 100:1 mix.
     
  3. fischer550

    fischer550 Member

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    Can you please post a link of one of those gauges that would work for a motorized bike? Thanks
     
  4. Theon

    Theon New Member

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    Probably cheapest to buy the temp gauge and the sensors separately.
    The temp guage was about $5 on Ebay from China.
    The sensors were about the same, again from China on Ebay.
    Locally the sensors were quite dear.
    The sensors I got also required the right plug for the guage. another $1?
    I tend to prefer my IR (point and shoot) temp sensor however, which was also very cheap from China on Ebay and has multiple other uses. But requires pulling over and should be done immediately, as the motor starts to cool quickly.
    Once the motor is set up there should be no real need for a temp gauge on most builds, but great tuning aid.
     
  5. Davezilla

    Davezilla New Member

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  6. Davezilla

    Davezilla New Member

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    I use an IR point and shoot gauge for reading my cylinder temp too... a real cheap and easy way to see exactly how hot your engine is getting, the gauge is great tho when you mount it because you can monitor it better while riding, but the point and shoot IR gauges are extremely accurate too
     
  7. Davezilla

    Davezilla New Member

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    So far the hottest I've seen my engine get right after a hard ride in 95+ degree Texas heat was about 320 F which is way below the danger zone (360 to 400)... These are cheap and accurate, and you can easily carry one with you on a ride, just pull over and shoot... right under the head near the exhaust port is going to show you the hottest spot, but you can experiment and find the hottest part real easy with this... http://www.ebay.com/itm/US-Contactl...hermometer-Temperature-Detecter-/111426841284
     
    #7 Davezilla, Aug 5, 2014
    Last edited: Aug 5, 2014
  8. fischer550

    fischer550 Member

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    So I bought this temp gauge, looks nice. So how do I use it to tune my engine? What am I looking for? Thanks!
     

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