What is it? 1980 CB750F carb part.

Posted: Mon Mar 19, 2012 6:54 am

Hi! Noobie here! I'm new to the DOHC's, just got a 750F, the carbs came in pieces in a plastic tote. It's a poor pic from my Blackberry, there's 3 of these bits and I can't find a reference to them. sbparks shows them in his carb thread. Thanks in advance! These carbs are far more complex than the SOHC's! Cliff.

Posted: Mon Mar 19, 2012 7:04 am

Those are called the needle jet. The pointy sharp thing on the slide is called the jet needle. The difference in the needle taper and the hole on the needle jet,ie the donut,determines the total fuel flow.

There is a threaded thing with a jet screwed into the bottom and this threads up against those things and holds them in. Normally you can unscrew that jet carrier and the needle jet will stay in place,but sometimes not and they just fall out so someone cannot figure out why the bike does not run right.

One side of them has a "crown" shape and this is down against the jet carrier. The concave side is "up" inside the carb throat.

Posted: Mon Mar 19, 2012 7:08 am

You also appear to be 1 short...should be 4 of them.

Posted: Mon Mar 19, 2012 7:16 am

Just found the 4'th one in a pile of screws - whew! Got where it goes. Now if I could just find the 4'th teeny tiny O ring!
Also, are there any downloadable parts books available?
Thanks again! Cliff.

Posted: Mon Mar 19, 2012 7:25 am

Thought I just explained that. EVERY bike carb has these even the old SOHC 750 carbs.

They are in the same hole the jet needle/slide operates. The front hole is called the primary main jet and is not it. The jet carrier threads in from bottom and holds it pressed up inside.,

Posted: Mon Mar 19, 2012 4:15 pm

Thanks again. Cliff.