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
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
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.
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.
@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.
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..."
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.
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
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
Here https://www.aliexpress.com/item/32851867757.html?spm=a2g0o.order_list.0.0.9c2218024NLrey I bought 2 sets to get the range I needed for pilot and mains. My larger ones that suit emulsion tubes are Japanese.
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
