emuwr3.jpg (9351 bytes)

This is enough wear to make a bike impossible to tune -
Poor mileage and rough, rich running is the result

Worn out NON-REPLACEABLE needle jets?

 25mpg Mileage  -  1/3 worse than original?        Needle jet orifice looks like an egg?

For much less than the cost of new carburetors - Factory Pro will replace your original, worn out needle jets with the brand new, better than original design, patented "HDJ" fuel delivery system.

Proven in many, many VL1500's in 2002 through 2014 - The Factory Pro HDJ System not only provides the correct amount of fuel, but, delivers the fuel in a more atomized state -  Tested with Belgarda Yamaha on the World Supersport circuit -

The patented "HDJ"  Fuel System allows the engine to extract even more power out of the same amount of air and fuel - simply because the smaller the fuel droplets, the more fuel will burn - the more power is produced!  (OK - it's not like it's 10% power - it's more like 2%-4% power improvement - but - it's cleaner and can be jetted even leaner without lean misfire for best mileage w/o surging.)

 rebuild normally non-replaceable needle jet carbs
at Factory Pro in San Rafael, CA on the following carbs.

Honda cbr600f2 / f3
Honda nt650
Honda cbr900rr

Kaw zx7r 96-03
Kaw zx9r, 94-97,98-99 and 02-03
Suzuki VL1500 - Famous!
Suzuki C-50 Volusia and Boulevard

415 883-5620
m-f 9-5 pacific time zone, for shipping instructions



  Rebuild Service Available needle jet type cost
cbr600f2 / f3, all years, all countries
needle jet rebuild rebuild service

inc needle jet replacement only

click here - to contact
HXX-02 to 05
$280 + S&H
NT650 twins and more
needle jet rebuild rebuild service

inc needle jet replacement only

click here - to contact

415 883-5620

m-f 9-5 Pacific time
HXX-02 to 05
twins $180 + S&H
cbr900rr, 93-99
needle jet rebuild rebuild service

inc needle jet replacement only

click here - to contact

415 883-5620

m-f 9-5 Pacific time
HXX-02 to 05
$280 + S&H
needle jet rebuild rebuild service

inc needle jet replacement only

click here - to contact

415 883-5620

m-f 9-5 Pacific time
H21-05 $280 + S&H
zx7r, 96-03, all countries

Feedback July 2014

HDJ needle jet Installation

"The new needle jets you installed fixed the problem created by the worn out stock ones.
Before, I could see the large drops (globs) of fuel being released between the needle and jet while it was idling (air box off).
Now I see nothing."

Greg Lowe

needle jet rebuild rebuild service

inc needle jet replacement only

click here - to contact

415 883-5620

m-f 9-5 Pacific time

To zx7r, 96-03 page
K90k-07-hdj $280 + S&H
zx9r, 94-97,98-99 and 02-03
(specifically not 00-01)

UK Feedback July 2014
Hi Marc just to let u know I finally got carbs from UK customs on Wednesday 23rd they sat on them for 10 days then had the cheek to charge me 70.00 pounds import duty bloody UK - any way, when I put the carbs back on bike it started first time and bike now goes so much better thank you and your team for their work very pleased and it now idles which it had never done before. Thank you very much.
It's just much better the whole way through the rev range but especially higher revs - just really impressed - thank you.
Karl Rouse  UK

needle jet rebuild rebuild service

inc needle jet replacement only

click here - to contact

415 883-5620

m-f 9-5 Pacific time

To 94-97 page
K90k-09-hdj $280 + S&H


vl1500lc, all years, all countries

Patented Factory Pro HDJ, multi-jet discharge needle jet.
Smaller additional fuel delivery holes for finer fuel droplets = better fuel atomization properties for potentially better power and mileage. (obviously depends on fine tuning)
This is an unplated HDJ for viewing purposes


patented HDJ needle jet

Long Boy A/F Screw
$20 a set with HDJ rebuild

Factory Pro VL1500 needle jet rebuild service includes:

2 new, installed, Ultra efficient, Factory Pro HDJ "Hi Dispersal" style needle jets ($280 value) 

If people are happy about how their bike runs after we rebuild them, part of the reason is the Marc Salvisberg / Factory Pro invented, patented HDJ style needle jet.

  • Patented HDJ system is far superior to other standard needle jets in fuel delivery.

  • Precision nickel plated for longest life to allow use of aluminum or Ti needles

  • Note: Factory Pro VL1500 jetting kits use aluminum needles

Factory Pro jetting kit ($90 value)

  • You tell us, Stage 1 or Stage 3 and we will install (we use our own aluminum needles for VL1500). Carbs set up for "average" conditions.

Long Boy Fuel Screw set ($40 value)

  • Easy "finger adjust" idle mix adjustment

  • no screwdriver required

Limited lifetime limited warranty to original repairee -  $100 (max charge) will rebuild needle jets, regardless of mileage or needle type.

Factory Pro was the first to recognize and provide a repair for the VL1500 carbs. Factory Pro is the only company to go through the extra work to nickel plate the needle jets for longer life and Factory Pro holds the HDJ patent.

Link to VL1500 Intruder page

S77-07-HDJ $280 + S&H

2 new HDJ needle jets
2  new aluminum needles
2 new pilot jets
2 new main jets
float bowl and carb top allen screws included

2 new Extended Fuel Screws

Vapour blast carb exterior:

Link to VL1500 Intruder page

Similar to VL1500 rebuild svc.
F-Pro Jet Kit (90)
Extended Fuel Screw (25)
new HDJ needle jet
$220 + shipping
($20 extra to clean external carb if required)

Link to 800 page

(415) 883-5620

VL1500 / VL800 Rebuild Service Turnaround:

Allow 5-7 working days for regular service.
Rush 2 working day service, add $40.

Pack carefully.
It's best to assume that the carbs will be dropped onto the surface of Mars and are supposed to bounce around for a while before opening.
3" to 4" thickness of  "bubble wrap" around the carbs works well.

Do NOT throw loose carbs in a box on "peanuts" - they will be bent when we get them.
Be careful - Remove any loose parts, like idle adjusters and cables and cable clamps before shipping.

Insure carbs for full retail $900 to $1000 value + whatever else you can think of.

Ship either "Overnight" or "Second Day".
The less time that the carbs are in transit, the less the chance of damage or loss

Include a note:
Return shipping name and address info
Telephone number
email address
What exhaust and air intake and anything else that you think might affect the tuning.

Even after jetting 1000's of bikes over the last 40 years, we won't be able to guess exactly about the "perfect" jet settings, but, extra info always helps (anybody who claims to be able to specify "perfect jetting" for every bike in every location, is a bit "too sure of themselves" or not very picky.  :-)

You can include credit card information in the note (not our preference) for payment - but we would prefer calling you and getting credit card info when we are ready to ship back to you.

Paypal is also an option.
If you want Paypal, tell us in your note and include email address and we will bill you when ready to ship.

Thanks -

Marc Salvisberg


 Mikuni 36mm carbs

This is an emulsion tube, (of which includes the needle jet) from a 36mm Mikuni carburetor.

There are basically 2 types:

The set for 3mm (.118") series needles and

the  set for 2.5mm (.098

') needles.

 Mikuni 36mm carbs


Factory Pro replacement number fits Mikuni size markings
100102k1221 3mm series needle Y-0, Y-2, Y-4, Y-5
100102k 2.5mm series needle O-6, O-8
"Square in a square"
This is the official Mikuni imprint.
It is on almost every jet that Mikuni makes.


Also, we can make larger needle jets upon request.


If you are replacing worn needle jets (emulsion tubes) and the tubes have no markings on them, they are probably dynojet tubes and they will not work with normal needles.

emuwr3.jpg (9351 bytes)

This is a worn 38mm Mik needle jet - It doesn't take too much to make a big difference!

This is a picture of the WORN needle jet area of an emulsion tube from a stock 38mm CV Mikuni carb as installed on Ducati,  Yamaha XTZ/TDM/TRX 850, YZF750, FZR/YZF1000, etc..
It has approximately ~5000 miles or  8000k usage.
Notice that the center hole is noticeably worn at the "V", the 12 o'clock position, which would be towards the engine, as installed in the carburetor.
This causes 2 conditions. First, it allows more fuel to enter the carburetor, as in using a needle with a small base diameter AND the fuel that enters the carb - it enters in larger droplets, resulting in poor combustion.
We carefully check needle jet condition on the vehicles when we create and install carb recalibration kits.
If you install a kit and it is much too rich at low rpm, and lowering the fuel level 1mm doesn't fix it, check the needle jets for any wear - it's not uncommon.
Additional:  Eventually, the carb body, where it holds the slide from rattling back and forth will wear out - allowing the slide to rattle and bang the needle into the needle jet orifice - causing accelerated wear.
Example: The original needle jet lasted 10,000 miles. After replacing the worn emulsion tube / needle jet, they only lasted 6,000 miles or less. That's because the slide guide slot in the carb body is worn - not because of the emulsion tube or needle is bad.



(partial, edited response to FZ1 Owners Group - April 5, 2003)

It a well known FACT that more experienced tuners know that NEEDLE JETS WEAR OUT.
They wear out on EVERY Japanese CV or slide type carb that has a needle - stock needles, stainless needles, titanium needles, bare 6061 needles and anything else that anybody else has made -

 It's a mileage and usage thing.

The more the mileage - the worse wear rate it is -
The bigger the cylinder - the worse rate it is -
The lower the rpm the bike is usually used at - the worse wear rate it is -
The worst wear rate are low rpm engines operated at low rpm - as in in-town -
The least worse wear rate - small engines operated at highway speeds -

It doesn't take a rocket scientist to figure out what happens if they have enough empirical data and a set of carbs in front of them.
The basic problem is that, at low rpm, the intake tract pressure fluctuations simply bang the slide back and forth in the carb's "slide guide" -
That rattles the needle in the bore of the needle jet and just bangs the needle jet, and if the needle is very soft - the needle AND the needle jet just rattle to a slow death - Ya takes your choice - one or both - Titanium seems to be the best choice - esp. over ss.
Mikuni knows that - that's why most CV Mikuni carbs have a step in the slide that spring loads/cocks the needle to one side to discourage deadly needle "rattle".
That's also why Keihin FCR's have actual bearings to keep slide rattle to a minimum (but noisy!) amount - Yep - needle jets STILL wear out in FCR's - and even wear out in the carbs of 250 GP bikes, like RS 250's, TZ250's and Aprilia 250's, too - amazingly enough!
If the slide guide in the less expensive CV carbs didn't wear out - that would make it "less worse" - but as the guide wears - the needle jet wear rate continues to accelerate as that slide rattle increases in amplitude -

We manufacture replacement:
FZR400, 88-89
FZR600 needle jets
gsxr / katana 36mm 2.5mm needle jets
gsxr 36mm 3.0mm needle jets
Triumph 900/1200 Mikuni 36mm needle jets
Ducati/TDM/TRX/XTZ 38mm needle jets
YZ/YZF 750/1000 38mm needle jets
FJ1200 needle jets
VL1500 needle jets
RF900/RF600 needle jets
cbr900 needle jets
Kaw zx900 (and other Kaw models)  needle jets

It would not be cost effective to make all these parts just to fix carbs with a specific brand of needle in them -
In an  informal poll - it looks like our needles were only in maybe 1 in 10 of these carbs - majority were unjetted - with stock needles - and the owner was going to rejet and experienced tuners would catch the wear before trying to jet a set of worn out carbs -

In addition - we are the only people that I know of that have a patent on needle jets that actually make replacement needle jets - We've probably looked at more worn needle jets on more different models than any one single facility in the world - We probably "should" know more than a chat group! Hopefully! :-)

Some wear can be compensated with by fuel level changes and we do specify on the website on models that are prone to wear  to CHECK before jetting -

Open eyes and open minds are terrible things to waste.