Problem with Mikuni Carb Body

Stripped screw/carb body problem.

That is, the screw is fine, but where it screws into on the carb body is stripped. Any quick fix for this?

We've seen longer screw/split washer (similar to OEM but longer) with a nut on the exposed end.  Not pretty but works fine.

Good Ridin'
slmjim & Z1BEBE

Which screw ??
If it's the float bowl or carb top i helicoil them.
Another alternative is to use a longer screw and nut or tap them out to M5..

zed1015 wrote:

Which screw ??If it's the float bowl or carb top i helicoil them.Another alternative is to use a longer screw and nut or tap them out to M5.. 

Where it screws into the carb body. This screw. For example, I can pull it out with my finger. It doesnt tighten so its stripped in the carb body that the screw screws into.

DanMadBoy wrote:

zed1015 wrote:

Which screw ??
If it's the float bowl or carb top i helicoil them.
Another alternative is to use a longer screw and nut or tap them out to M5..



 

Where it screws into the carb body. This screw. For example, I can pull it out with my finger. It doesnt tighten so its stripped in the carb body that the screw screws into.

Attachment not found

Ok! It's the float bowl.. So the alternatives are as in my reply listed above.
Maybe the easiest fix for you is simply a longer screw with a nylock nut on the other side.

zed1015 wrote:

DanMadBoy wrote:

zed1015 wrote:

Which screw ??
If it's the float bowl or carb top i helicoil them.
Another alternative is to use a longer screw and nut or tap them out to M5..





 

Where it screws into the carb body. This screw. For example, I can pull it out with my finger. It doesnt tighten so its stripped in the carb body that the screw screws into.

Attachment not found

Ok! It's the float bowl.. So the alternatives are as in my reply listed above.
Maybe the easiest fix for you is simply a longer screw with a nylock nut on the other side.

 

I was updating the attachment. Its where it screws into the carb body thats stripped. See below. I can pull this screw out with my fingers!!

 

I've used 4mm Rivnuts in this situation on dozens of carb sets over the years.it pulls into the carb body as far as the lip and the knurled portion grips the carb. A stripped 4mm thread is the perfect size to grip the knurl so don't even need to drill the hole bigger.
Can't pull through, can't spin, you end up steel/steel threads not steel/soft cast ally.
simple and effective. 
Simple fix. 
Picture for illustration 

I would try to glue a M4 nut on top of the carb body with JB weld first, it´s non inversive and removeable.
Rivets can crack the zinc carb body easy and can cause more damage and trouble you didn´t want.

Scirocco wrote:

I would try to glue a M4 nut on top of the carb body with JB weld first, it´s non inversive and removeable.
Rivets can crack the zinc carb body easy and can cause more damage and trouble you didn´t want.

I've done dozens of them Scirocco. Never had one crack yet. The metal is quite thick there and has the extra thickness of the external rim. The way to do it is to use a bowl screw with a washer on. Put it up through the striped thread from underneath without the bowl in place. Screw the Rivnuts on with the flange uppermost then slowly wind the screw up which pulls the Rivnuts down into the cab body. Once it's seated is not going anywhere and the screw force is spread over the surface diameter of the lip rather than a few alloy threads. 
The trick is knowing what your doing and the skill to do it. 

Scirocco wrote:

I would try to glue a M4 nut on top of the carb body with JB weld first, it´s non inversive and removeable.
Rivets can crack the zinc carb body easy and can cause more damage and trouble you didn´t want.





 

Yeah Im not going to do that.

DanMadBoy wrote:

zed1015 wrote:

Which screw ??If it's the float bowl or carb top i helicoil them.Another alternative is to use a longer screw and nut or tap them out to M5.. 

Where it screws into the carb body. This screw. For example, I can pull it out with my finger. It doesnt tighten so its stripped in the carb body that the screw screws into.

 

All taken care of. I have the bolt and the nylon washer. Had a SS set among my tools etc.

DanMadBoy wrote:

zed1015 wrote:

Which screw ??If it's the float bowl or carb top i helicoil them.Another alternative is to use a longer screw and nut or tap them out to M5.. 

Where it screws into the carb body. This screw. For example, I can pull it out with my finger. It doesnt tighten so its stripped in the carb body that the screw screws into.

 

Noticed the hex head fastener.  Those are a recipe for stripping threads in soft alloys very easily.  Float bowl screws don't have to be King Kong tight.  If the gasket's not fresh, over-tightening the screws won't help anyway. Suggest a torque screwdriver such as those used in the gunsmith trades.to reduce the likelihood of over-tightening & stripping small hex fasteners in soft metals.

Good Ridin'
slmjim & Z1BEBE