main jets

i have a 82 50 seca
the guy who had it before me put pods on it and changed the main jets from 120 hitachis to 115 mikuni
so naturally it runs very lean on main curcuit
the problem i face is that i can not find hitachi jets anywhere but mikunis are available and do thread in
my question is will the mikuni jets work(bike runs great now just lean)

if not where can i get hitachi jets possibly an assortment my 650 is lean as well

 

Hey Brent!! Check out Chacal's thread in the FOR SALE section, he'll hook ya up...he's the man for parts for these bikes. YAY CHACAL!

 

Oh, yes.... there will be jets.

-------------------

Main & Pilot Fuel Jets:


ee) Aftermarket Hitachi brass MAIN FUEL JETS, sizes as follows, fits all XJ650 (except Turbo), all XJ750, and all XJ700 (exc. "X") models.

NOTE: stock Hitachi XJ series carbs used the following original sizes:

#106 (XJ 750RL Seca, 1984 only)
#107 (XJ700 non-X)
#110 (XJ650 models)
#120 (all XJ750 models except 1984 XJ750RL Seca)

All the other sizes are for "tuning" or re-jetting purposes when changing intakes or exhaust systems.


HCP6316 Aftermarket brass #106 MAIN FUEL JET, stock size for '84 XJ750RL Seca models, each: $ 6.00

HCP6316SET4 Aftermarket brass #106 MAIN FUEL JET, set of 4: $ 21.95

HCP6317 Aftermarket brass #107 MAIN FUEL JET, stock size for XJ700 non-X models, each: $ 6.00

HCP6317SET4 Aftermarket brass #107 MAIN FUEL JET, set of 4: $ 21.95

HCP6318 Aftermarket brass #108 MAIN FUEL JET, each: $ 6.00

HCP6318SET4 Aftermarket brass #108 MAIN FUEL JET, set of 4: $ 21.95

HCP6319 Aftermarket brass #109 MAIN FUEL JET, each: $ 6.00

HCP6319SET4 Aftermarket brass #109 MAIN FUEL JET, set of 4: $ 21.95

HCP873 Aftermarket brass #110 MAIN FUEL JET, stock size for most XJ650 models, each: $ 3.25

HCP873SET4 Aftermarket brass #110 MAIN FUEL JET, set of 4: $ 11.95

HCP874 Aftermarket brass #112 MAIN FUEL JET, each: $ 3.25

HCP874SET4 Aftermarket brass #112 MAIN FUEL JET, set of 4: $ 11.95

HCP875 Aftermarket brass #116 MAIN FUEL JET, each: $ 3.25

HCP875SET4 Aftermarket brass #116 MAIN FUEL JET, set of 4: $ 11.95

HCP876 Aftermarket brass #118 MAIN FUEL JET, each: $ 3.25

HCP876SET4 Aftermarket brass #118 MAIN FUEL JET, set of 4: $ 11.95

HCP877 Aftermarket brass #120 MAIN FUEL JET, stock size for most XJ750 models, each: $ 6.00

HCP877SET4 Aftermarket brass #120 MAIN FUEL JET, set of 4: $ 21.95

HCP878 Aftermarket brass #122 MAIN FUEL JET, each: $ 3.25

HCP878SET4 Aftermarket brass #122 MAIN FUEL JET, set of 4: $ 11.95

HCP879 Aftermarket brass #124 MAIN FUEL JET, each: $ 3.25

HCP879SET4 Aftermarket brass #124 MAIN FUEL JET, set of 4: $ 11.95

HCP880 Aftermarket brass #126 MAIN FUEL JET, each: $ 3.25

HCP880SET4 Aftermarket brass #126 MAIN FUEL JET, set of 4: $ 11.95

HCP881 Aftermarket brass #128 MAIN FUEL JET, each: $ 3.25

HCP881SET4 Aftermarket brass #128 MAIN FUEL JET, set of 4: $ 11.95

HCP882 Aftermarket brass #130 MAIN FUEL JET, each: $ 3.25

HCP882SET4 Aftermarket brass #130 MAIN FUEL JET, set of 4: $ 11.95

HCP883 Aftermarket brass #132 MAIN FUEL JET, each: $ 3.25

HCP883SET4 Aftermarket brass #132 MAIN FUEL JET, set of 4: $ 11.95

HCP884 Aftermarket brass #134 MAIN FUEL JET, each: $ 3.25

HCP884SET4 Aftermarket brass #134 MAIN FUEL JET, set of 4: $ 11.95


xx3) Reproduction Hitachi main fuel jet SPACER WASHER, round flat copper washer goes under the head of the main fuel jet. Perfectly replaces missing or bowed originals.

HCP887 Hitachi carbs main fuel jet spacer washer, each: $ 4.50

HCP887SET4 Hitachi carbs main fuel jet spacer washer, set of 4: $ 15.00


ff) Aftermarket Hitachi PILOT FUEL JET, sizes as follows, fits all XJ650 (except Turbo), all XJ750, and all XJ700 (exc. "X") models.

NOTE: stock Hitachi XJ series carbs used the following original sizes:

#36.5 all XJ700 non-X models.
#40 all XJ650 models, all XJ750 (USA) models, and XJ750RL Seca (1984).
#43 some Canadian-Euro-UK XJ750 models.


The #41, #42, sizes can also be used for "tuning" or re-jetting purposes when changing intakes or exhaust systems.


HCP885 aftermarket brass #40 PILOT FUEL JET, each: $ 3.25

HCP885SET4 aftermarket brass #40 PILOT FUEL JETS, set of 4: $ 11.95

HCP886 aftermarket brass #41 PILOT FUEL JET, each: $ 3.25

HCP886SET4 aftermarket brass #41 PILOT FUEL JETS, set of 4: $ 11.95

HCP6326 aftermarket brass #42 PILOT FUEL JET, each: $ 5.50

HCP6326SET4 aftermarket brass #42 PILOT FUEL JET, set of 4: $ 19.95

HCP6320 aftermarket brass #43 PILOT FUEL JET, each: $ 5.50

HCP6320SET4 aftermarket brass #43 PILOT FUEL JET, set of 4: $ 19.95





WHAT ABOUT RE-JETTING FOR PODS, ETC?:

It's a question we get asked often and unfortunately, one that we cannot answer honestly about your specific bike besides with "it depends".

Which is a nice way of saying "you're about to enter the seventh circle of hell......."!

Carb jet tuning required by aftermarket modifications is somewhat of a black art, part science, part skill, part luck. It depends on the current state of tune of your engine, your altitude, the mix of aftermarket parts on your bike, etc........a lot of variables.

The best advice we can offer is: Just Say No. Don't do it! Leave everything stock!

But, since most people---with good reason, I might add---don't always listen to our well-intentioned advice, then the next best recommendation we can offer is: "if you want more power get a bigger bike!".

And since that doesn't cut it with many owners, either, for the remaining stalwarts out there who insist on "experimenting" with aftermarket intake and exhaust systems, here's the best information that we've come across to give you some GUIDANCE, which you should take as just that, and not as ANSWERS, because it isn't!





MAIN FUEL JET SIZE CHANGES NEEDED PER TYPICAL MODIFICATION:


Typical Exhaust Changes:

+2 main fuel jet size for custom 4-into-2 exhaust

or

+4 main fuel jet sizes for 4-into-1 exhaust

or

+4 main jet sizes for no muffler (open headers)


Typical Intake Changes:

+2 main fuel jet sizes for single K&N filter (inside a stock airbox)

or

+2 main fuel jet size for drilling holes in the airbox with stock filter

or

+4 main fuel jet sizes for individual pod filters (no airbox)


Additional changes:

- Add up all the main fuel jet size increases and subtract 2 sizes.

- Decrease main fuel jet size by 2 sizes per every 2000' above sea level.

- Under a mis-match condition, such as when using pod filters with a 100% stock exhaust, or 4-into-1 header with stock filter and air box, then subtract 2 main fuel jet sizes.


PILOT FUEL JET SIZES CHANGES NEEDED PER TYPICAL MODIFICATION:

Pilot fuel jet size changes are related only to the change in main fuel jet sizes according to the main fuel jet size formula described above. Note that this pilot fuel jet rule is for the main fuel jet size change BEFORE any main fuel jet altitude compensation is factored in:

Increase the pilot fuel jet size +1 for every +3 main fuel jet size increases.

Additional changes:

- Decrease pilot fuel jet size by 1 for every 6000' above sea level.



PRECAUTIONS:

- Make sure your carbs are in perfect working order before making jet changes....meaning fully cleaned internally and rebuilt, operating properly in their stock configuration, proper sized air jets and needles, etc.

- Check plug color often and adjust as needed, 2 main fuel jet sizes at a time and 1 pilot fuel jet size at a time. Bright white plug insulators are a sign of an overly lean fuel mixture condition and WILL cause damage to your engine over time, up to and including engine seizure!

- Synch the carbs after each jet change.

- Make sure the floats are set correctly

- Seriously consider purchasing a Colortune Plug Tuning kit.

- You may find it necessary to make changes to the size or shimming of the main jet needle. There are no guidelines on what or how to do these changes, this is true trial-and-error tuning!




EXAMPLE:

A 1982 XJ750RJ Seca using an aftermarket Supertrapp 4-into-1 exhaust and a single K&N air filter in the stock, unmodified airbox. Bike is primarily operated at an altitude of 2600 feet above sea level.

XJ750 Seca Stock Carb Settings:

#120 Main Fuel Jet
#40 Pilot Fuel Jet
Y-13 Needle


MAIN FUEL JET SIZE CALCULATIONS:

Changes made:

Exhaust:
4 into 1 with Supertrapp = +4 Sizes Main Fuel Jet

Intake:
K&N Pod Filters = +4 sizes Main Fuel Jet
----------------------------
Equals: +8 main fuel jet sizes above baseline
Subtract: -2 main fuel jet size per formula above
----------------------------
Equals: +6 main fuel jet sizes due to modifications, thus:

Stock main fuel jet size is: #120
+ 6 additional sizes
= a #126 main fuel jet size
---------------------------
Subtract: -2 main fuel jet sizes for Altitude of 2500' Average

= #126 calculated from above
-2 jet sizes for altitude adjustment

= a #124 main fuel jet size.


PILOT FUEL JET SIZE CALCULATIONS:

The formula is: +1 pilot jet size increase for every +3 main jet sizes increased.

Stock pilot fuel jet size is: #40
+ 2 additional jet sizes (since we went up +6 main fuel jet sizes before the altitude compensation was factored in):

= a #42 pilot fuel jet size.

Note that no altitude compensation is needed on the pilot fuel jet since our elevation is less than 6000' a-s-l.


------------------------------

RESULT:

A #124 Main and #42 Pilot is A GOOD STARTING POINT.

******************************************************


For further insights and understanding, the Holy Grail (meaning: the whole miserable, un-varnished truth of what a real chore carb tuning is going to be, written by people who actually know what they're talking about, rather than by people who are trying to sell you something) can be found at:

www.factorypro.com

and then click on the "Product Support/Technical Support" link at the top of the page, then on the "Motorcycle Tuning Tech" link, and then the "CV Carb Tuning" link........and then read, weep, study, and do....if you still dare to! As you will soon realize, it's takes quite a bit of effort to properly tune a carb to its optimal performance----another reason why we don't suggest using pods!

----------------

PM Chacal for ordering. Now, if you'll excuse me, I need to get back to turning this price list of his into a PDF.

 

rejetted my 750 with 124 mains now 1 and 2 are still white and 3 and 4 are now coveder in soot dry black soot before they were all white my plan is to replace the two plugs and rejet to 126 why would two be covered in soot


rejetted my 650 with 116 mains and instead of white the ceramic is now a light red is this ok

 

How do I get intouch with Chacal, I'm new to the site and have looked everywhere for jets.

Can't find the for sale section of this site

 

"Forum index\XJ4Ever- Supporting Vendor"