Main air jet on 39 FCR

puggy · Oct 25, 2006

I have sucumbed and bought an ex 2003 WR 450 fcr39 carb to fit to my 2002 400 FE (Fixermans old bike) and have already hit a stumbling block , I can't seem to find the main air jet ,looking at the diagrams on the Sudco site it should be next to the pilot air jet at the rear of the carb ,but mine just has a small hole without any apparent jet or thread.

The serial number on the side of the casting is 5TJ2 1ORC04

Any ideas?
Brilliant forum, loads of simple improvements that even a newbie like me can make.

Taffy · Oct 26, 2006

welcome puggy and hope you'll get involved here. could do with a few more brits on the board.

you have a later carb mate. they decided that there was no need for the MAJ. very few people understood it anyway (on the whole of TT i was the only one) so you're missing nowt. it was the last nth of thee nth degree of tuning.

regards

Taffy

puggy · Oct 26, 2006

Thanks Taffy

Thank you for that Taffy , can you tell me if the following settings you posted earlier still apply, I know you carry out extensive testing for which I for one am most grateful.
The bike is standard throughout
158 MJ
DMT needle
35 Pilot jet
.028 apj
1.5 turns out on pilot screw
number 75 starter jet
Or
162 MJ
EKQ needle on clip4
40 PJ
60 Pilot air jet
.028 APJ
Number 75 starter jet
1.5 turns out on pilot screw

Taffy · Oct 26, 2006

Re: Thanks Taffy

puggy said:
Thank you for that Taffy , can you tell me if the following settings you posted earlier still apply, I know you carry out extensive testing for which I for one am most grateful.
The bike is standard throughout
158 MJ
DMT needle
35 Pilot jet
.028 apj
1.5 turns out on pilot screw
number 75 starter jet
Or
162 MJ
EKQ needle on clip4
40 PJ
60 Pilot air jet
.028 APJ
Number 75 starter jet
1.5 turns out on pilot screw

first of all nothing is quite that literary. you'll need to start there and deal with whatever comes up. i didn't realise i put up DMT? mmmmm? where was this?

far prefer the EKQ and you can also consider the lineaweaver needle. dodn't forget that the APJ is a number for the MK1 carb that had the external rod going down the right hand side ok?

also, went to the #80 choke jet in the spring so that the bike would start immediately and nearly flood. whereas with the #75 it would start 3rd or 4th kick but i could go off to the loo and come back and she'd be chugging nicely. i needed the #80 to start in races and immediately pull off.

ask if you need to.

regards

Taffy

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Main air jet on 39 FCR

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