mikuni idle screws

I've got the Mikuni BS28 carb on my bike (XJ550).

When I went to adjust the idle mix using my new Colortune, I discovered that the idle mix screw was quite seized, and a little stripped. Now, it's a *lot* stripped and I suspect I will need to drill it out. Has anyone had this happen, and if so, where can you go to get a new screw to replace it? Is there anyone parting out one of these carbs?

Thanks!

Owen

 

Yup, been there done that.

First, getting the screw out:

Use pen lube, some kind of impact (e.g.,hammer on an old screw driver, impact driver...), and heat. Might want to use heat as a last resort.

I used an 1/8th easy-out. (THe screw type).

Drill into the center of the screw using a 1/16th bit. Then go to 1/8th. Try and only go about 3/16ths below the top of screw. If you drill deeper you'll seperate the threads from the metering needle on the bottom.

But if the easy-out strips, then go deeper to get a better bite. You'll just have to get the needle part out some other way--e.g., like a pair of really small pliers. There'll be a brass and a rubber washer that has to come out of there as well.

Next, take your screw driver and make it a perfect fit to the other good pilot screws. That is, a perfect fit. File it, grind it, what ever, just make it fit real good.

Next, wait until a new/used pilot screw arrives in the mail.

I'll have to check, but I'm pretty sure I've got an extra one. P.M me for details.

 

I "tried" to do this. My #1 carb was stripped. I tried to easy out it, but I broke that off in the thing. Colortuned color shows it burning slightly rich, but not bad, so I am just letting it be as it is. If you break it off, you have to get a machine shop to drill it out for you or buy a new carb ($140+)

 

Thanks for the replies.

I was thinking it might be a bad idea to use heat to to the proximity of the bowls, but I have used a great deal of penetrating oil and various sizes of drivers...

No dice, so I will be drilling it this evening.

 

Owen...

send me a PM or email me...

i will have some carb parts available in the very near future. near like with in a week or so...

d