1990 XJ 600 37kW --> 54kW

Hello forum users,

I've been following this forum for some time now while rebuilding and modyfying my XJ600 and I have finally decided to come out

I have this issue with my motorcycle - It is a stock version from Germany 37kW - 54hp, I would like to convert it to original 54kW - 72hp. While searching for clues how to do it I found a post on a forum for german speaking Yamaha drivers of a guy who did the conversion in a dealership. Below is the information from the invoice that he received afterwards:
Intake manifolds:
49A-13586-00 49A-1
49A-13596-00 49A-2
49A-13597-00 49A-3
49A-13598-00 49A-4

Needle Jet 1, 3, 4 51J-1490J-00 4CP3
Needle Jet 2 51J-1490J-10 4CP7

I've already installed the intake manifolds. Now I am in the middle to cleaning my carbs and I would like to buy the parts that I need but when I looked up the needle jets numbers in the carb parts section of this forum I was surprised to find out the they come from XJ550. I wouldd appreciate any help in verifying this information.

 

Hmm 51J teh correct prefix is for XJ600. My suggestion would be to get a complete Mikuni BS32 carb rack from a UK model they can be had pretty cheap - especially if it's just for spares..

Also what TCI do you have? They may have restricted the maximum rpm too..

 

I am not sure there were any different TCI's models for XJ600 / FJ 600. From the invoice the German guy received it's obvious Yamaha used different intake boots with airflow restrictions and a different carb set up. I drove the bike before I started disassembly process and it reved nicely on all gears.
If it's just needle jets that I am missing, It'll be cheaper to source only these.

 

Ok - at least you checked - might be worth posting a 'wanted' item on the for sale section here..