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Post by eric123 on Apr 17, 2008 21:27:58 GMT -5
Does any one have a chart that lists the drill sizes that approximate the mikuni jet sizes??? My apologies if one has been posted before, but I haven't found it...
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Post by eric123 on Apr 17, 2008 21:38:49 GMT -5
Found it...
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Post by 5twins on Apr 17, 2008 23:23:40 GMT -5
I'd like to see that. Can you post a link?
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nebos
Junior Member
78 Special
Posts: 53
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Post by nebos on Apr 18, 2008 6:44:58 GMT -5
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Post by eric123 on Apr 18, 2008 11:46:28 GMT -5
nebos beat me to it...That was the first one I found, I have found a few other too...A handy bit of info to have in pinch...Its nice to figure out what jet I need without having to buy a variety... |
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targis34
Full Member
'81 xs650 special stock
Posts: 186
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Post by targis34 on May 12, 2008 20:08:48 GMT -5
I just tried to get a set of drills to drill out a pilot jet but the best I could come up with was a 1/4? size bit which fit a 20 pilot jet but nothing to drill to a 22.5.....I will look for the kit you suggest. We don't have a harbor frieght but we do have Princess Auto which I think is similar.
What do the numbers mean.. Are the metric or just some numbering system???
Mike
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Post by 5twins on May 12, 2008 23:04:24 GMT -5
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Post by crazypj22 on Jun 6, 2008 13:19:43 GMT -5
only problem with that link to jet sizes is ....it isn't right.
Kei-Hin use hole size for jet size.
Mikuni use flow rate in cc/min or litres/hour @ 20" head (pressure, not sure how its arranged?)
PJ
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panic
New Member
Posts: 49
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Post by panic on Jun 6, 2008 13:58:18 GMT -5
Not a good idea except in an emergency (i.e., no other way to get home). Why?
1. this is a twin: you'll never, ever, get 2 jets the same size, or match an existing jet using a drill. Even a reamer is not all that good.
2. the ID is not the only thing that determines flow rate - also tapers before and after the hole, and the exact position of the hole in the jet length.
The chart on the linked site refers only to Mikuni jets that are sized by diameter, not flow rate (as are N/042 for the VM), and he estimates that the flow rate is exactly proportionate to the new ID: wrong.
From the linked site: "You should use a drill press for drilling your main jet"
WRONG, wrong, wrong. Use a pin vise and turn it by hand.
There are even errors in his math: #55 (.052") is 1.32mm, not 1.33mm.
Safe use: use drills to get progressively larger sizes (in pairs) for testing only, then you only have to buy the jet size right around your best choice.
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Post by eric123 on Jun 17, 2008 23:08:16 GMT -5
Not a good idea except in an emergency (i.e., no other way to get home). Why? 1. this is a twin: you'll never, ever, get 2 jets the same size, or match an existing jet using a drill. Even a reamer is not all that good. 2. the ID is not the only thing that determines flow rate - also tapers before and after the hole, and the exact position of the hole in the jet length. The chart on the linked site refers only to Mikuni jets that are sized by diameter, not flow rate (as are N/042 for the VM), and he estimates that the flow rate is exactly proportionate to the new ID: wrong. From the linked site: "You should use a drill press for drilling your main jet" WRONG, wrong, wrong. Use a pin vise and turn it by hand. There are even errors in his math: #55 (.052") is 1.32mm, not 1.33mm. Safe use: use drills to get progressively larger sizes (in pairs) for testing only, then you only have to buy the jet size right around your best choice. Drilling the jets for testing and then buying the appropriate jets is what I had in mind...Thanks for the info and suggestions... |
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Post by themayor on Mar 29, 2009 9:56:07 GMT -5
I am not sure i would even do a drill out then buy the size you need. No matter what size drill you use I am sure you will dealing with some amount of runout. You may end up with two different size holes. Bad idea. jmo
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Post by coupelx on Jan 5, 2010 15:20:17 GMT -5
drilling jets is very common in the atv world and especially banshees when converting to alcohol because they dont make jets big enough. They make more power than most xs's could ever dream of so it must work fine.
my bolt on banshee makes as much power as my 650 with 300 less cc's.
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Post by tiredguy on Mar 7, 2010 18:24:03 GMT -5
You can drop by just about any machine shop and see if they will check your drilled jets with pin gages. then you'll know what your jet diameter is down to a few tenths...depending on which pin it will pass and which one it won't.
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camo
New Member
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Post by camo on Aug 22, 2010 15:31:10 GMT -5
I have drilled jets many times on a drill press set to a very slow speed with plenty of cutting fluid. it has been a great tool for identifying what jet size the bike needs, then fine tune the carb and let it run. I agree about the taper Adan run out, but we are not dealing with 16K rpm high performance motors here, these XS motors are very forgiving.
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Post by acmewrench on Sept 16, 2011 21:55:37 GMT -5
Jet drills are available, sized, and should be used with extreme caution. I agree, replace the jets if you can wait or if you're in a hurry, take heed and know the consequences of using the aforementioned methods. I'm new to this site so please accept my first humble post.
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Aug 23, 2016 7:57:01 GMT -5
Aug 23, 2016 7:57:01 GMT -5