crf450, 02-04, jet, carb, tune, tuning, Data by EC997a Eddy Current Dynamometer

Honda crf450r

02-06

Factory Pro's
patented HDJ MAJ installation for crf / wr / yfz
Keihin FCR carbs

Where's my main air jet and what do I do with that drill bit and tap that came in my Factory Pro HDJ kit for my Keihin FCR carb?

First step is to eliminate the fixed main air jet restriction.
It's about 40mm down the MAJ hole (left picture).

Set your 3mm drill so that it has 45mm to 46mm of drill bit exposed from your drill chuck.
(see right picture)

Remove the stock emulsion tube (that's what the main jet screws into) so that you can clean out the carb well. By only having 45mm to 46mm of the drill bit exposed, it prevents you from drilling too far.

Then, use the supplied tap from our HDJ carb kit, thread the Main Air Jet (aka "MAJ") hole.
You only need to go far enough to be able to thread in the new replaceable jet that we supply.

Clean the hole, of course.

After it's clean, complete the MAJ Modification by installing the supplied Main Air Jet and installing the new Factory Pro HDJ Emulsion Tube.

NOTE!!!
If you aren't confident in your ability or in your understanding of what you are trying to accomplish - no worry - Call us up or talk to someone locally who has more experience in these matters.
If you are still not sure, see if there's a Factory Pro Tuning Center locally or visit your favorite local dealership or shop and get some help there -

We all have to learn, and "usually", having an experienced person around makes everything "easy".

This modification is something similar to what we've done in many different carb types over the years, though it might be new to some who haven't used our "1.7-RK" carb kits before.

	To adjust float height: Sooo.... You read the carb kit instructions and they specify a 15mm float height. Float height? What's a float height? 15mm? How much is that in inches? (it's .590") Does that mean I must do it??? YES! Gee whiz! What do I measure with?? You can use a set of vernier calipers, if you have them - they are great for measuring all sorts of things, but you can make it even easier with our... Float Level Setting Gauge Measures from 0mm to more than you will ever need! Easier to use than vernier calipers on carbs. The vertical legs adjust in width and the thin post slides up and down so you can slide the post to the required clearly marked float height measurement.
	Remove float bowl screws. Factory Pro gives you replacement allen screws in most carb kits to replace usual phillips screws.
	Slide the lower movable leg so that both legs will rest on what would be called the gasket surface of the carb body (if there was a gasket, anyway)
	Tilt the carbs so that the floats just flop over towards and into the carb body. Tilt just enough to touch and close the float the float valve, but... Do NOT compress the float valve spring when measuring (only exception is 95-97 zx6r) Test adjust the "L" horizontal arm in the usual 1mm increments and test fit the guage to see what the float is set at now. (or not). (If we say 15mm and you measure 4mm less than that - you might be compressing the little float valve spring.) At this time, you can set the Float Height Guage to what you want to reset the floats to. If you are tuning, you'd usually use 1mm increments
	CV Carbs: Too RICH at full throttle / low rpm (that's the most common in CV carbs) Slide carbs (FCR's) - Float height controls 25% throttle at ALL rpms. If the float height is too low (small float height measurement), bend the tab slightly to increase the height measurement. It's a 5:1 movement ratio. CV: If the float sticks out further, down, into the float bowl, the carb will deliver less fuel (leaner), especially at low rpms and at cruise. Slide carbs: Float height controls 25% throttle at all rpm's, even at redline. You'd generally change the float height in 1mm increments when tuning. It will affect the topend slightly. Maybe 1.5mm leaner float height would require 1 size larger main jet to keep equal main jet fuel delivery.
	CV Carbs: Too LEAN at full throttle / low rpm (not too common in CV carbs) Slide carbs (FCR's) - Float height controls 25% throttle at ALL rpms. If the float height is too LARGE, bend the tab slightly OUT to decrease the height measurement. If the float sticks out further, UP, into the carb body, the carb will deliver MORE fuel (richer), especially at CV low rpms and at cruise. It will affect the topend slightly. Maybe 1.5mm richer float height would require 1 size smaller main jet to keep equal main jet fuel delivery. You'd generally change the float height in 1mm increments when tuning. When you are done, a multi-cylinder must be all within .5mm (1/2mm) or .020" range of each other.
	Nifty baffle plates in the 05 KLX300!
	This carb type has been around since the early 80's! It's had some updates over the years. It's similar to the Ninja 900'a and ex250 styles.
	A view from the engine side, butterfly open.

Absolutely NO carb parts sold in California.

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The extension of the laboratory for engines of the Swiss Federal Institute of Technology was completed in about 1935. Its architect was Rudolf Otto Salvisberg (1882-1940). He had a successful career in Berlin but returned to Switzerland after the advent of the Nazis. His architectural style was somewhat similar to that of Erich Mendelsohn. The staircase of the laboratory is in normal use but well preserved.
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