VM26 (clone) vs PZ30 help

[pistolclass]

35 is pretty fat for a vm26 229cc bike. If the bike is totally stock I would start with a 110 main or 112.5 max and a 22.5 or 25 max pilot.

If you open it up with air box + exhaust then go 115 or 120 main and 25-30 pilot.

I don't know for sure but I would think you would need to really do some head work in order to need a 35 pilot.

My hawk runs and starts great, stock exhaust and air box with a 110 / 20 combo. I realize the 20 is a little lean but I made up for it with setting the needle at its richest setting and I'm 2 turns out. I will eventually install my 22.5 that is on my bench but it is running so good I really don't want to mess it up.

These are all starting points, not sure fire solutions. Good luck on you quest to tune your carb.

FYI I'm at 200 ft above sea level and It is 80+ degress.

[Ariel Red Hunter]

Originally Posted by Megadan

Personally, I would get the following sizes for a Hawk with a VM26.

Pilot. 25, 27.5, 30
Main:105, 107.5, 110, 112.5, 115, 117.5, 120

This range of jet sizes would cover and fine tune everything from completely stock on a hot day to cold temperatures on a bike with full bolt ons.

Great point....ARH

[Hawk 229cc]

thank you plan is to try the 30 an 110 at 1010 feet where i live that can go up an down when i go into the valley ,moded air box but will put more holes in it ,going with cfr 230f
aftermarket exhaust ,we may , i see some guys just doing a good size air filter then useing the air box to store small things or delete it ? ,but plan is to get it as much air to it an thus as much power back from it ,the lack of power is ok ,but need a bit more i am sure the mods they suggest will be noticed in a few weeks ,week after 4th ,will have most of the suggested mods done,fun bike though ,starts right up an runs ok with the stock carb but just starved for air ,oh an neutral has been very easy to find ,feelling like i am 3rd gear when it is in 5th ,i am sure you know,time to wake it up

only pilot i dont have yet is the 27.5 ,probley the one i will need Naaaaaaaaaaaaaa will see,i will have my carb buddie look at this thread as i get a good shcooling in doing it myself ,big hands small parts

Edit to add that from 400 feet to 1000 ,around an 80 mile radious

[Gh426]

found this... http://www.historicmotorcycle.org.au...carby/jets.txt

Being a CHEAP SKATE / SCOT (Wny can confirm this I will put my $4. .3mm-1.6mm HSS ebay kit to test. If i goof up, i will try the plumbers map gas torch lead soldering of said jet to go smaller. Others seem to get away with this

If anyone has tips, trycks or additional info ?? please speak up

FYI this acticle seems to be Ninja 250 centric so YMMV

CARBY JET SIZES
---------------

Everybody uses different methodology to establish their number for their given type of jet.

Mikuni for example, use a few different type of main jets in the various carbs commonly found on motorcycle engines.
Each of their different jets are tested and calibrated in different ways.

So for example, the Mikuni Long Hex, Short Hex, and Round-SlottedHead Jets in #71 size are 3 different Calibrations.
Besides the Physical differences, the Flow Rates are different.


Anyway, by whatever method that's used,
Jet Numbers are representative of a VOLUME of fuel.

CC's or Grams, usually per minute

So #71 Mikuni jet would flow about 71cc's of Gasoline per minute.
.................................................. ..
"Car" carb jets and the old Fuel Injection "Pills" are usually calibrated in numerical sizes according to Orifice Diameter.

Even then, the Jets are Labelled according to a Code, of sorts.

Holley Carbs for example, I can't recall Exactly how they determine the Number stamped on the jet,
but they Drill a bunch of jets during a production run.

Imagine the Hole Size being .071".
Then they will Flow Test all the jets in that batch.
Some will be LABELLED #70,,,some #71,,,some #72.

Meaning,,,they Drill & Finish the jets as precisely as practical,,,,and they are a NOMINAL #71 Batch.
Then Beyond That,,,they are Tested and labelled according to actual Flow Rates.
....................................
DynoJet Brand of Re-Jet Kits is very popular among motorcycles tuners.
They use Hole Size in Millimeters to label their jets
So a Dyno Jet Brand of jet for a Mikuni or Keihin Bike Carb ,,labelled as a #71 Jet,,,,
is actually 0.71 MM orifice diameter

I guess Bottom Line,,,among all the variety of jets,,,there's No Rhyme or Reason,,,or Standard.

They ALL are ultimately based on Fuel Flow Rate.
Because THAT is what is most convenient and accurate to MEASURE.

It is always most practical to number each graduation of Flow Rate sequentially.

But each Mfgr has their Own Scheme for translating Tested Flow Rate into a "Jet Number".

"A Rose by any other name....",,,
However they do it,,whatever they Call it,,,,it's all a Measurement & Ranking of Fuel Flow rate.

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JET MM INCHES NUMBERED JET SIZE
SIZE DRILL BIT WHEN DRILLED
#66 0.66mm 0.02598" #71
#68 0.68mm 0.02677"
#70 0.70mm 0.02756" #70 @ .0280" 71.12jet
#72 0.72mm 0.02835" #69 @ .0292" 74.2 jet
#79 0.79mm 0.0312" 1/32"@ .0312" 79.2 jet
#80 0.80mm 0.03150" #68 @ .0310" 78.7 jet
#83 0.83mm 0.03268" #66 @ .033" 83.8 jet
#89 0.89mm 0.035" #65 @ .035" 89 jet
#91.5 0.915mm 0.036" #64 @ .036" 91.5 jet
#96.5 0.965mm 0.038" #62 @ .038" 96.5 jet
#101.5 1.015mm 0.040" #60 101.5 jet
#105 1.05mm 0.0415" #59 @ 1.06mm 106 jet
#110 1.10mm 0.043" #57 @ 1.11mm 111 jet
#115 1.15mm 0.0455"
#120 1.20mm 0.047" #56 @ 1.19mm 119 jet
#125 1.25mm 0.049"
#130 1.30mm 0.051" #55 @ 1.33mm 133 jet
#135 1.35mm 0.053"
#140 1.40mm 0.055" #54 @ 1.40mm 140 jet

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The main Jap carbs are Mikuni and Keihin, Mikuni 6mm hex Jets are numbered by flow,
Keihin are by jet size 134.5 is 1.345mm.

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Dynojet - Mikuni - Keihin jet sizes conversion
From Ninja250Wiki

When you're jetting your carbs you will notice that the same size jets from different suppliers have different numbers.
The following chart will give you an idea of which numbers are the same for the different companies. Remember, though,
that this will only put you in the ballpark. Plenty of trial and error will be needed to get it right.

A note from Dynojet:
We are often asked for a "cross reference" sheet that compares our main jets to Mikuni or Keihin.
The fact is you cannot directly interchange the jets for a given size. Many things affect fuel flow through
a jet of the same orifice size. The entry and exit tapers of our main jets differ from those of other companies.
Due to this, the fuel flow changes as a function of velocity through the carburetor venturie.
This means that two jets of equal orifice size will have a different fuel flow curve relative to intake air speed.
At a certain speed the two may flow equally, but a change in velocity changes the flow characteristics.
The Dynojet main jet hole size is measured in millimeters. For example, a DJ142 has a 1.42mm hole.
Michael Cory
Dynojet Research & Development

Available jets
You never know what kind of jets you might find at your local shop when you try to find new jets.
Wes says to just ask for jets that will fit in a Harley. That keeps the sales droid from having to think too much.
Asking about Ninja 250s causes all sorts of confusion. Having this chart, and knowing what will fit and how they
compare to each other, will help you figure out if they have what you can use.

There are four current sources of main jets which will fit the Ninja 250:

1) Keihin - OEM main jets - Jets are measured using an unknown convention in steps of 2 or 3.
Available from Kawasaki dealers 2 sizes larger and 2 smaller than the Ninja 250's stock #105 main jets.

2) Dynojet - Measured in mm. Dynojet numbers are simply the hole diameter. A 140DJ main has a 1.40mm (0.055")
diameter hole in it at the threaded end. Available in .02mm increments. Marked with a 'DJ' on the jet.

3) Precision Engineering - Also sold under the names 'RD Precision Engineering' and 'Freeman Automotive'
All are marked with an 'AB' on the jet. Like Dynojet, measured in mm, but come in .025mm increments.

4) Mikuni - Made for Mikuni Carburetors, but will also fit Keihin. 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.

The measurements in this chart are from the actual measured orifice size, in millimeters. Keihin 105 is the stock main jet.


unknown = Not yet measured
n/a = This size not available from this manufacturer

Measured mm Keihin Dynojet Precision Mikuni Flow(cc/sec)
(AB)
.94 unknown DJ094 n/a 87.5 2.19
.95 n/a n/a AB95 n/a 2.24
.96 unknown DJ096 n/a 90 2.29
.975 n/a n/a AB97.5 n/a 2.36
.98 100 DJ098 n/a n/a 2.38
1.00 102 DJ100 AB100 92.5 2.48
1.02 105 DJ102 n/a 95 2.58
1.025 n/a n/a AB102.5 n/a 2.61
1.04 108 DJ104 n/a 97.5 2.69
1.05 n/a n/a AB105 n/a 2.74
1.06 110 DJ106 n/a 100 2.79
1.075 n/a n/a AB107.5 n/a 2.87
1.08 unknown DJ108 n/a n/a 2.90
1.10 unknown DJ110 AB110 102.5 3.02
1.12 unknown DJ112 n/a 105 3.13
1.125 n/a n/a AB112.5 n/a 3.16
1.14 unknown DJ114 n/a 107.5 3.25


Again, the chart is fine to use to get you in the ballpark. However, once you start zeroing in on the correct
jetting specs, you should be basing your jetting changes based on what the bike is telling you--not what someone
else (who isn't testing with you) says is right for your bike/situation.
There aren't really any shortcuts to getting jetting right.

Read the rest of the information in the jetting section at
http://faq.ninja250.org/wiki/I_want_...uretor_jetting

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Dellortos are rated by size, so a 120 main is actually 1.2mm

http://www.bikechatforums.com/viewtopic.php?t=17124

Mikunins are measured by flow rate so a 120 main flows 120cc/min

http://rd500lc.free.fr/technics/jet_size_en.htm

Good Dellorto tuning book:

http://www.morinispecial.it/manuali/...ning_guide.pdf

If you could find a way to flow test all the dellorto jets and all the mikuni jets you have then
it would be pretty easy to put together a comparision chart between the two. Keep in mind that
not all jets of the same # will flow the same amount due to machining diffrences (see first link).

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Mikuni, Dynajet, and Kehin all have different drill sizes for the same jet number:



drill Dell'Orto # drill Adler
inches --- Kehein # -- DynoJets # -- Mikuni # -- mm --- Bing #

0.035 ----- 92.5 ------- 92 ---------- 86.3 ----- 0.92
0.036 ----- 95 --------- 94 ---------- 88.1 ----- 0.94
0.037 ----- 97.5-------- 96 ---------- 90.0 ----- 0.96
0.038 ---- 100 --------- 98 ---------- 91.9 ----- 0.98
0.039 ---- 102.5------- 100 ---------- 93.8 ----- 1.00 ---- 110
0.040 ---- 105 -------- 102 ---------- 95.6 ----- 1.02
0.041 ---- 107.5------- 104 ---------- 97.5 ----- 1.04 ---- 115
0.042 ---- 110 -------- 106 ---------- 99.4 ----- 1.06
0.043 ---- 112.5------- 108 --------- 101.3 ----- 1.08
0.044 ---- 115 -------- 110 --------- 103.1 ----- 1.10
0.045 ---- 117.5------- 112 --------- 105.0 ----- 1.12 ---- 120
0.046 ---- 120 -------- 114 --------- 106.9 ----- 1.14
0.047 ---- 122.5------- 116 --------- 108.8 ----- 1.16
0.048 ---- 125 -------- 118 --------- 110.6 ----- 1.18
0.049 ---- 127.5------- 120 --------- 112.5 ----- 1.20
0.050 ---- 130 -------- 122 --------- 114.4 ----- 1.22
0.051 ---- 132.5------- 124 --------- 116.3 ----- 1.24
0.052 ---- 135 -------- 126 --------- 118.1 ----- 1.26
0.053 ---- 137.5------- 128 --------- 120.0 ----- 1.28
0.054 ---- 140 -------- 130 --------- 121.9 ----- 1.30
0.055 ---- 142.5------- 132 --------- 123.8 ----- 1.32
0.056 ---- 145 -------- 134 --------- 125.6 ----- 1.34
0.057 ---- 147.5------- 136 --------- 127.5 ----- 1.36
0.058 ---- 150 -------- 138 --------- 129.4 ----- 1.38
0.059 ---- 152.5------- 140 --------- 131.3 ----- 1.40
0.060 ---- 155 -------- 142 --------- 133.1 ----- 1.42
0.061 ---- 157.5------- 144 --------- 135.0 ----- 1.44
0.062 ---- 160 -------- 146 --------- 136.9 ----- 1.46
0.063 ---- 162.5------- 148 --------- 138.8 ----- 1.48
0.064 ---- 165 -------- 150 --------- 140.6 ----- 1.50
0.065 ---- 167.5------- 152 --------- 142.5 ----- 1.52
0.066 ---- 170 -------- 154 --------- 144.4 ----- 1.54
0.067 ---- 172.5------- 156 --------- 146.3 ----- 1.56
0.068 ---- 175 -------- 158 --------- 148.1 ----- 1.58
0.069 ---- 177.5------- 160 --------- 150.0 ----- 1.60
0.070 ---- 180 -------- 162 --------- 151.9 ----- 1.62
0.071 ---- 182.5------- 164 --------- 153.8 ----- 1.64
0.072 ---- 185 -------- 166 --------- 155.6 ----- 1.66
0.073 ---- 187.5------- 168 --------- 157.5 ----- 1.68
0.074 ---- 190 -------- 170 --------- 159.4 ----- 1.70
0.075 ---- 192.5------- 172 --------- 161.3 ----- 1.72
0.076 ---- 195 -------- 174 --------- 163.1 ----- 1.74
0.077 ---- 197.5------- 176 --------- 165.0 ----- 1.76
0.078 ---- 200 -------- 178 --------- 166.9 ----- 1.78
0.079 ---- 202.5------- 180 --------- 168.8 ----- 1.80
0.080 ---- 205 -------- 182 --------- 170.6 ----- 1.82
0.081 ---- 207.5------- 184 --------- 172.5 ----- 1.84
0.082 ---- 210 -------- 186 --------- 174.4 ----- 1.86
0.083 ---- 212.5------- 188 --------- 176.3 ----- 1.88
0.084 ---- 215 -------- 190 --------- 178.1 ----- 1.90
0.085 ---- 217.5------- 192 --------- 180.0 ----- 1.92
0.086 ---- 220 -------- 194 --------- 181.9 ----- 1.94
0.087 ---- 222.5------- 196 --------- 183.7 ----- 1.96
0.088 ---- 225 -------- 198 --------- 185.6 ----- 1.98
0.089 ---- 227.5------- 200 --------- 187.5 ----- 2.00

[Cravin01]

The elusive pilot jet of the PZ30 can be found on ebay and Aliexpress.

https://www.aliexpress.com/item/Moto...822840523.html

The knock off pumper PZ30 does have needle hight adjustment which the PZ30 that came on the bike does not, I'm too far in with the Kehein's to turn back but so far I've had good experiences with them.