White spark plug.

Discussion in 'Motorized Bicycle General Discussion' started by fischer550, Jun 1, 2014.

  1. fischer550

    fischer550 Member

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    I just finished a build yesterday and was just cruising today for about 5 minutes at no more than half throttle. I am at elevation 5,000 feet, and I was running 16:1 (I know most on here disagree with that, but fred at crmachine.com recommended it to me). I didn't do the WOT plug chop because I don't want to run it too hard during break in, but I took off the plug and it was 100% white, which I thought was odd because it was 4 stroking a lot. Any suggestions? The stock NT jet is in there now. Should I lean out the fuel mix?
     
  2. GearNut

    GearNut Active Member

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    What number ( heat range) is the spark plug? If it is too hot it can burn off the color imprint you are looking for.

    I don't want to assume nor do I want to offend you but I need to ask, are you positive it was 4 stroking and not actually surging?
     
  3. fischer550

    fischer550 Member

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    The spark plug is B8HS-10 provided with the top end kit from fred. And no offense take, I don't even know what surging is
     
  4. fischer550

    fischer550 Member

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    And by the way guys, when I say "white" I don't mean there is a whit residue, I just mean that no oil is showing up on the plug.
     
  5. Davezilla

    Davezilla New Member

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    Sounds like it was surging from being lean and not 4 stroking to me... white with no ash or residue is Way too lean. I'd check the carb to make sure there's no junk in the carb blocking off the main jet because even with a stock jet at 16:1 it shouldn't show that lean.

    Surging is when you're cruising along and the engine basically keeps dying and jumping forward from fuel starvation, it usually feels like the engine is cuting out but with a bit of a kick to it as it fires on the next stroke...
     
  6. fischer550

    fischer550 Member

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    I will check that in the morning, because at one point the engine did just bog out so maybe thats it.
     
  7. fischer550

    fischer550 Member

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    But what you're describing is not really what I felt, it felt like 4 stroking cause when I revved up a little higher it went away
     
  8. fischer550

    fischer550 Member

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    Update: I messed with the carb a bit, here's my observations:

    I had the c-clip on the needle at the top notch (leanest as I am in Denver) The motor was running OK, 4 stroking a little bit on the bottom but real zingy at the top, the only problem was there was no presence of oil on the plug.

    So, I moved the c-clip down 2 notches as well as cleaned out the jet and the motor was 4 stroking through all rpm's and running real bad. After this I checked the plug, and there was just a tiny bit of oil on the plug but it was still way white. Eventually, the motor started surging and then completely bogged down where I could not ride it anymore :( please help
     
    #8 fischer550, Jun 1, 2014
    Last edited: Jun 1, 2014
  9. mapbike

    mapbike Active Member

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    Im with Dave sounds like a lean condition surge and Fred is telling you wrong in the opinion of most of us who know better here, 16:1 is way to much oil, if the oil you're running is a high quality oil, personally I'd go to a 32:1 mix and continue to take it eazy like you have been and chances are you'll actually be a little on the rich side with a 32:1 mix and that is a plenty safe mix with good oil.

    After a couple tanks of gas I'd use the mix I plan to run in It from now on and tune the carb accordingly and you should be just fine.

    Map
    .wee.
     
  10. fischer550

    fischer550 Member

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    So do you think if I switch to 24:1 and do nothing else, more oil will appear on the plug?
     
  11. fischer550

    fischer550 Member

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    And that can't be right I don't think map, because when I moved the c-clip down I richened the mix, right?
     
  12. mapbike

    mapbike Active Member

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    Yes if you move the clip down it will cause the needle to sit higher at its lowest point and that allows more fuel to flow up from the main jet at idle to about 3/4 throttle.
    Doing what you described does richen the mix at idle and low to midium speeds, I set my carbs so the jetting is correct at the speeds I plan to cruise at, that will mean that the mix will be slightly on the rich side below those rpms and cause a slight amount of 4 stroking at low to midium speeds but none at cruise speeds or when engine is under a heavier loads like going up hills and slight inclines.

    A 32:1 mix gives you more fuel in the mix to a lesser amount of oil, a rich condition is related to the fuel not the oil and that is also true for what is a lean condition, more oil in the mix means less fuel in the mix which means a leaner mix.

    Hope this help explain things a bit better.

    Map
     
    #12 mapbike, Jun 1, 2014
    Last edited: Jun 1, 2014
  13. mapbike

    mapbike Active Member

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    Its not a matter of more oil its about the fuel when dialing in carb to be correct as far as not being to lean or not to rich, oil does the lubrication and fuel does most of the cooling when carb jetting is correct.

    24:1 is a much better mix than 16:1 in these engines, its still way more oil than I would ever or have ever run in any of mine but skme think its a good starting point based on their experience so I ont debate that point, I just know what has worked perfectly for me so if it aint broke I dont fix it as the old saying goes....

    Switchint from 16:1 - 24:1 should richen your fuel a bit but you'll just need to do a plug chop to know for sure what it does.

    Map
     
  14. Jumpa

    Jumpa New Member

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    fischer550

    Map is giving you very good advice , he has numerous bikes and they are always running in tip top shape. I do believe he still has his very first original motor he got started into this hobby with & that motor has thousand of miles on it .

    I cant remember exactly how many miles, however that can attest to the fact he knows what he is talking about also he isn't trying to sell you anything so you can count of the information he is giving you has no ulterior motive "like some peoples might" I'm not saying anyone does just that they might. In other words. Map is a trustworthy man in my opinion !!
     
  15. fischer550

    fischer550 Member

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    yes map bike has very good advice. my problem is that I am worried because I have a brand new motor and no oil is showing up on the spark plug, thats something that Ineed to fix right away and I don't know how to do it
     
  16. fischer550

    fischer550 Member

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    So I switched my fuel mix to about 27:1 and went out for a quick 3 minute ride. I kept the stock NT jet, but moved the c-clip back to top notch (I live in Denver). Performance wise, it was 4 stroking pretty bad at most rpm's but it was running at least, I took off the plug and although it did look better, it's still looks pretty white to me. Here are some photos, and the last one is of the bike.
     

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  17. fischer550

    fischer550 Member

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    Great news. I switched the jet from the stock NT to a smaller jet, a 66, and took her for a 3 mile ride. Came back, took off the plug and to my delight it was a nice dark brown!
     
  18. crassius

    crassius Well-Known Member

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    I've sometimes noticed that a high quality plug may take a while for anything to show on it.
     
  19. Dan

    Dan Staff
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    Good news, Fischer.

    Sweet lookin' ride too!
     
  20. mapbike

    mapbike Active Member

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    Excellent....glad to hear you're getting that little china beast tamed down.

    Always feels good to get a problem resolved and then it starts to get fun again...!

    Map
    .wee.
     

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