06-04-2010, 08:46 PM #1
- Join Date
- Sep 2006
Is a keihin #60 jet the same size a mikuni #60?
I need to make a fuel line restrictor for the 750 I just sold. All the threads here say to use about a #60 mikuni jet. All I have are keihin jets laying around. I have a #65 to be exact. Are the numbers the same size between the two brands?
06-04-2010, 08:59 PM #2
- Join Date
- Oct 2006
- Cleveland OH
Close enough for a restrictor.
06-05-2010, 12:20 PM #3
I was told the jet numbers are not the same. Mikuni jet's are measured in thousands. With no idea how the Keihin are measured,but pretty sure larger.
Do you have any really tiny drill bits, to do some kind of comparison ?
06-05-2010, 12:34 PM #4
I think mikuni is measured in thousands as casey mentioned and the Keihin are measured in flow (cc) at a certain PSI.
06-05-2010, 12:45 PM #5
a mikuni jet size #60 isn't .060 a 135 jet is very close to .055,the virage runs a mikuni main jet #60 for a return jet (3 carbs on 2 pumps)the pro runs a .060 drilled jet for the return (3 carbs 3 pumps) clear as mud right
06-05-2010, 02:10 PM #6
No, they're not the same.
Mikuni = Measured in flow
Keihin = Measured in size (some formula)
1) Keihin - OEM main jets - Jets are measured using an unknown convention. Measurements are based on orifice diameter size.
2) Mikuni - Made for Mikuni Carburetors. Available in 2.5 increments. Mikuni uses yet another measurement convention - reportedly based on flow rate. The result is that Mikuni's sizes are vastly different from the other makers'.
The different manufacturers' jets will have a slightly different taper to the orifice, which can affect flow. This means that there will most likely be very slight differences between the same diameter jets from different makers.
06-05-2010, 02:46 PM #7
Re: Is a keihin #60 jet the same size a mikuni #60?
Oops I had it backwards.
06-05-2010, 03:47 PM #8
neither is measured in thousandths.its a scale all to its own.which brings up this confusion as well.when talking about jetting stingers on pipes make sure when given specs for setting the jets you clarify wether they're talking a JET size or a jet with a .000" size.ie you should run a 150 jet.is that a#150 jet or a jet at .150" if you look at the pro785 water routing it refers to sizes as .125" and .090".
06-06-2010, 02:26 AM #9
I had some time to kill this afternoon I found some small drill bits to match a couple jets.
The Keihin #105 is pretty close to .037 inches ( on my cheap calipers),that drill bit fit a bit loose in a Mikuni # 105 jet.
A Keihin #145 was about .052in , the Mikuni # 145 was a lose .056in.
So itlooks like the Keihin jets are smaller. Sorry if my previous statement caused any confusion.
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