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Info Chinese Jet Kits: Any Good?

Discussion in 'Tech Tips' started by maelstrom, Jul 14, 2022.

  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Following on from @ruckusman reporting that emulsion tube sizes were out by 0.07mm in Chinese jet kits, here is a vid I made about the main and pilot.

    Cheers
    Blair
     
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  2. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That is very well done - measuring the ebay/Aliexpress emulsion tubes was enlightening for me 0.07mm change in the Mikuni range is a significant increment and would have a BIG change on fuel metering by the needle
     
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  3. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

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    @maelstrom what brand of pin gauges are they?
     
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  4. jmw76

    jmw76 Well-Known Member

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    To be fair measuring Chinese jets with Chinese pin gauges and chinese micrometer is all very interesting. Are the instruments calibrated? A comparison measurement might be more meaningful. Are the OEM jets actually of better accuracy? What does an old jet measure as a comparison? Sorry Blair, I skipped through your video, so you might have actually addressed this. Good work all the same.

    I typically purchase a range of jets at a time and then test, change and retest on the bike over many sessions to arrive at the best performance. I just use the number on the jets as a guide as to which way to go.

    Note: mikuni jets are typical marked with flow rate and not jet diameter.
     
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Seriously, you think I use Chinese micrometers? All of my micrometers are Mitutoyo and of course I zeroed it. It does not matter if the pin gauges are Chinese. It only matters what diameter the pin gauge is, and that is why I measured each and every one of them in the video. I also have Japanese pin gauges and I always measure them prior to use too. I did measure OEM jets in the video.
    Finally, I know that Mikuni jets are rated by flow.
    Mic.jpg
     
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  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    @Frankster The pin gauges I used in the video are just some Chinese jobbies. The ones I used were all acceptable for size as you can see in the video. I never trust any pin gauges and always measure them first anyway. I can't vouch for their durability, but for the limited use they will get, fine for me.
     
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  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    From ebay out of either Hong Kong or Taiwan IIRC - I purchased some pin gauges 2.500mm - 2.700mm in 0.010mm increments and 3.500mm - 3.600mm in 0.010mm increments, all measured as accurate with a brand new, calibrated Mitutoyo, mircon accurate micrometer and they are all accurate - yes I'm even staring through a loupe at the 0.001 gradations

    I was sceptical when I hit buy, but they all measured up accurate!

    @maelstrom hath made me fussy when it comes to measuring it seems...blessing or curse?
    Said the Zen Master..."We'll see..."
     
    Last edited: Jul 15, 2022
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    OMG 0.001 :)
    You know that it all gets a bit mental when you get down to those numbers. You have to start factoring in ambient temp etc. 0.01mm is okay for us mortals.
     
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  9. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    It all depends on exactly what you are measuring.... :thumb_ups:
     
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  10. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I bought the micrometers because guessing at (+-)3-4 micron accuracy for crank and rod journals just sucked because the shell thicknesses span micron ranges also

    Sometimes you just need to be absolutely certain
     
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  11. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

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    I purchased some pin gauges 2.500mm - 2.700mm in 0.010mm increments and 3.500mm - 3.600mm in 0.010mm increments.

    Do you have a link to the ones you purchased? There's so many it's almost confusing. I understand what @maelstrom is saying about the micrometer being the tool that confirms the thickness, so it doesn't really matter where I get the pin gauges from, but if someone else has them and they're working well, then I'd be happy to go with a known supplier. Cheers
     
  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    They're big sets and a good price

    I got mine from this vendor on ebay - one was labelled as 3.520mm, etched with the same 3.520mm, which measured up as 3.500mm - obviously a mistake in the labeling, nd packaging they replaced it without issue very promptly

    https://www.ebay.com.au/sch/i.html?...&store_name=speedingstar&_oac=1&_nkw=pin gage
     
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