Sheared idle mix screw

[dt1903]

Picked up a set of carbs and have discovered that the idle mix screw at some point has been tightened way to much and when I took them out discovered that the needle end is still in the carb body!

Any ideas on how to get it out?!

 

[Scorpio1963]

I assume you broke the tip off in the carb body?This has happened to a lot of people on here.If you search you will find your answer

 

[dt1903]

Not me this time!

But yea the needle tip is stuck. Been trying a few techniques I know but no cigar just yet. Was seeing if anyone had any snazzy tricks for this

 

[Scorpio1963]

I have hear of people drilling them out but its very risky,if you make the hole to large where the tip of the needle goes your basically screwed.Its been a while since I looked at a carb body for these bikes but maybe you can turn the body so that you use a small something or another and punch or push it out.

 

[Recreateme]

I had this issue, and made a thread about solving.

Long story short i drilled it.

I went to a hobby store and bought numerous tiny bits, from smallest to largest diameter that i could match to the tip size. I started with the smallest and managed to break like 4 drill bits until i got to one that was about the size of the hole and just used it to push the sheared off tip downward into carb and out. My left carb has a slightly larger then stock idle needle hole now. But it runs better then having a broken tip stuck into it.


The two common ways are to try to push it back up out of the carb, using something small like a thumb tack bent at 90 degrees.

or

Buy a tiny drill bit and drill it out,

or

Push it all the way through and end up with an enlarged hole.

I think i would proceed with them in that order as that is the safest to least safest way of doing it.

Searching around the forum will give you a few threads on this topic. Best of luck

 

[dt1903]

Cheers.

Yea, I'm not mad keen on drilling it but its starting to look like i'm going to have to. They are wedged in there good and proper.

I reckon dremel, tiny drill bits and a lot of patience will do the trick.

 

[xschris]

http://www.xs400.com/forum/showthread.php?t=11329&highlight=broken+screw Here is a good thread.

 

[dt1903]

Cheers chris. Ended up drilling them this morning. Prob will need the idle mix screws down lower now but holes look pretty good. They were basically fused to the body! Must have been like that for a long time

 

[xschris]

The size bit should be a .45mm what size did you use? The only thing that should have been drilled is the brass that was stuck in the hole.

 

[dt1903]

Yea that's what I went for. Screws are now sitting well. Going to get it running and see how it goes!

 

[xschris]

Have you replaced the broken screws with new ones?

 

[dt1903]

Yea of course.

 

[bcware]

I would think it should be tune-able. You'll just have different settings than stock. Let us know how it goes!

 

[dt1903]

For anyone that is interested...

Managed to get the carbs tuned today with the drilled idle screw holes. Its worked pretty well. They are only about a 1/4-1/2 turn further in then the recommended.

The hardest thing was feeling resistance when screwing them down as the hole is ever so slightly bigger.

But it works!

 

[xschris]

Good to hear

 

[Sid1015]

Anybody know where to get the idle screws for a bs34. The one that broke on my bike doesnt look like the ones ebay offers. This is what it looks like.

 

[xschris]

Those type are for the 77-79 xs400. Google the part number and you should be able to find them. Yamaha still had these a while back. After some looking, these seem to be getting hard to find. I did find these http://www.boats.net/parts/detail/yamaha/Y-2A2-14923-00-00.html

 

[Sid1015]

Thanks i found it. Part number
2A2-14923-00