"The Haynes Manual STING" Reversed Data & Corrections.

HAYNES

YAMAHA XJ 650 & XJ 750 Fours

653cc - 748cc. 1980 to 1984
OWNERS WORKSHOP MANUAL

Haynes 738
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Page: 114
Chapter 2 Fuel System and lubrication

Specifications section:
Carburettors XJ650 models

Data in Manual reads:

Main air jet .................... 50
Pilot air jet .................... 195

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Page: 115
Specifications section:
Carburettors XJ750 models

Data in Manual reads:

Main air jet .................... 80
Pilot air jet .................... 225
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The POSITIONS of these two Jets, in the photograph appearing on pg. 123, are CORRECT.
3 Holes - Right side looking down and in.

LABELING of the 2 Jets is NOT Correct.

NOTICE:
Jet with LARGEST orifice Labeled (A) Main Air Jet -> [Incorrect]
Jet with LARGEST orifice [Top position in photo] is: PILOT AIR JET *

Jet with SMALLEST orifice Labeled (B) Pilot Air Jet -> [Incorrect]
Jet with SMALLEST orifice [Center Position in photo] is: MAIN AIR JET *

*See Photo



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Revised:
May 23, 2007

With many thanks to Nick who deserves credit for clarifying this whole situation.

 

Now this is useful information from Rick and something I have seen referred to from time to time but haven't gotten around to checking.

Must check my Haynes '85 XJ900 manual to see if the reversal of numbers is there as welll.

Karl

 

I thought the labeling of the picture is not correct, and was the error in the manual?

If you feed a thin wire down the "central hole" labeled "B" in the photo, it will come out at the top end of the chamber where the needle jet resides, which is the main jet. Therefore "B" is the Main Air Jet in the photo.
You can also follow the exterior casting ridges and follow the porting path for each air jet.

 

Hey! that's great info.
However if one were to catalogue ALL the errors in a Haynes it would be a BIG job.
These manuals are best known for their cheap pricings... not their accuracy.

 

Rick, the picture you posted confuses me. The bottom one in that picture is obviously 80, so it is Pilot Jet and the top one is 225 which is the main jet. .... you caption you added says the opposite.

 

A confession:
In all the years I've owned my Haynes, I've never encountered any errors. Guess I just never paid enough attention (usually only look up torque tables and schematics). I have to say that I find my Haynes to be rather well set up but lacking somewhat in the detail department. A fine maintenance manual otherwise.

 

OK..?
Clearly.. you've not had the opportunity to use a factory manual.. an entirely different world.
Hell even the Clymer's are significantly superior to any Haynes and that's a scary thought
PS: usually the TQ #'s in a Haynes are suspect if not downright wrong..a traditional/perennial error source in any Haynes. But Hey! they are $20

Hunt around.. I believe OEM manuals and even Clymers are available for download

 

I have the Clymer's manual.....no Haynes here. I haven't seen any glaring errors in it yet.

 

These are NOT Fuel Jets. Quantity of FUEL Metering is NOT the issue.

These are AIR Jets. Volume of AIR is regulated by these Jets.

The AIR Passages of the TOP Jet are cast and drilled to connect to the Pilot FUEL Jet.
The TOP -> AIR JET <- [despite it having a LARGER Metering Port with a Larger Number stamped on the collar] IS ~~> The PILOT Air Jet!

Likewise ...
The AIR Passages of the MIDDLE Jet are cast and drilled to connect to the void surrounding the EMULSION TUBE. This AIR JET Meters the flow of AIR to the space surrounding the Emulsion Tube above the MAIN FUEL Jet.

The LOWER -> AIR JET <- [despite it having a SMALLER Metering Port with a Smaller Number stamped on the collar] IS ~~> The MAIN Air Jet!

 

ok, now that makes sense...

thanks for the clarifications.

 

I've been meaning to pick up a factory manual for years, never seem to remember it when ever there is some spare change jingling in the pocket. I guess I ought to put it on my Christmas wish list. Of course that means I would have to be a good boy the rest of the year...

 

I just bought a factory service manual off ebay for $25. It covers the maxims and secas, supposedly, still waitng for it.

 

I think everybody who has a bike with the skimpy "USA Distribution Tuning" should can them "On-The-Lean-Side" Main, Pilot, Main-air & Pilot-air Factory-to-California ... de-tuned for Emissions Regulations and NOT for the way the Bike was intended to perform, cut-back, low-performance, boggin'-out and back-firing fraud, substituted for an EPA stamp and rider un-friendly, Limbo under the regulation and please the smog police jetting.

 

I found this out the hard way after I rebuilt my carb. It would just flood the cylinders with fuel. I burned the book after(just kidding).

 

I can vouche for what Rick posted. Rick and I spent about an hour on the phone last week discussing this situation. I got an 83 xj650 for free and it needed carb work. I pulled the carbs and stripped em dowm to just the bodies soaked everything and reassembled using the manual. Upon firing it up it was way fat on gas. :roll: I tryed everything and finally posted on here for advice. The haynes manual is definetly wrong on this issue. THANKS TO RICK!! He is the man!!