1975 CB125 Carburetor Issue.

[lucaspa]

Hello All.
First off I just want to say I appreciate everyone's posts on this site. I have been using the site a lot during my builds and have found a huge amount of knowledge that I could not get else-ware. I will eventually start a build site and post some pics however for now I have a question that hopefully someone can answer.

I have been building a 1975 CB125S2 and have recently dis-assembled and cleaned the carburetor. The carb is a Keihin 660A (per print on the carb body). When re-assembling the carburetor I found the needle jet holder, valve seat, and main jet assembly (picture below) would not screw all the way into the carb body. The threads on both the carb body and needle jet holder look okay but the needle jet holder will not screw in. Upon further inspection I noticed that one end of the needle jet holder is flared out. When I looked down the carb throat it looks like the needle jet holder has busted off and the other half is still seated in the carb body. The first picture below shows the piece of copper sticking up into the carb throat, I am thinking that this is the other end of the needle jet holder? This is my first build so I am not sure this is the issue. So my first question is: is the needle jet holder broken off? and the second question: if it is how can I get the rest of the bugger out? Thanks in advance for any advice.

Cheers

 

[lucaspa]

Sorted it out. In case anyone else runs into the same issue, the needle jet is tapped out from the top of carb body down towards the float bowl. Need new needle jet, holder, and possibly main and slow (pretty dirty) which I am having trouble finding. The original parts have been discontinued by Honda.

 

[SONICJK]

Lucas,
It is very rare that you need to replace the brass parts in a carb, unless you're changing sizes.
Get yourself a can of carb cleaner and soak the jets, blow them out with compressed air, and maybe if its necessary put a single strand of copper wire through the jet orifices. No need to buy new ones.

 

[Dave Walters]

Lucas,
It is very rare that you need to replace the brass parts in a carb, unless you're changing sizes.
Get yourself a can of carb cleaner and soak the jets, blow them out with compressed air, and maybe if its necessary put a single strand of copper wire through the jet orifices. No need to buy new ones.

If the brass pieces are mushroomed they might be able to be fixed or needed replaced.

 

[lucaspa]

SONICJK,
I think I may be able to salvage the main jet and possible the needle jet holder. I cleaned them out pretty well with a copper wire and then some nylon guitar string and I can see daylight through them now. Like Dave mentioned though the needle jet is mushroomed and not seating properly in the carb body. It will not allow the needle jet holder to screw all the way down.

I managed to find this online though and it may suit my needs, although not incredibly cheap.

http://www.ebay.com/itm/360608779235?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

I am tempted to purchase a Mikuni VM22-133 as it is only 75$. Let me know what you guys think.

:

 

[SONICJK]

Try

jets-r-us

Sirius Consolidated

Or look up the OEM part number on cmsnl.com and order it through honda.

 

[teazer]

The needle jet holder/emulsion tube does not screw in all the way. That's how it is designed. If the needle jet is damaged, your will probably find almost any Keihin NJ from that era is the same. They came in three different heights, but 90+% were the same bore and OD.

That Needle jet looks fine in that picture. They are fairly short.

 

[lucaspa]

All great info. Thanks guys. With the advise I got things sorted out. I ended up getting a new needle and needle jet on the cheap however like teaser mentioned I don't think I needed them as the threads don't have to go all the way down. Can't hurt to have a spare around A good cleaning took care of the slow and main.Thanks again for the help.
Cheers.