Cleaning a Carburetor XJ750 - Screws Wont come out

So I took the carburetor out of my bike, and started pulling it apart to give it a good clean. I've got the whole thing in pieces except two of the screws to take off the covers that you gain access to the vacuum chamber (pic attached). There are four screws in the corner of each cover and two of the screws on the same cover just wont budge, I've practically stripped the heads at this point and there's not much to grab with a screw driver anymore. Just looking for some advice on how to get those bad boys out of there. Anything helps!

Thanks,

Ross

 

Get thee to a hardware store and procure a handheld impact driver forthwith.



Use a good penetrating oil (PB Blaster, Kroil, 3-in-1) and carefully tap on the end of the driver to help loosen the screws. If the impact bit does not grab at all then you can use a small cold chisel against the edges of the screws, perpendicular to the head to rotate the screws out. Another alternative (and really the best for at home) is to buy a set of left-handed drill bits. The bit usually grabs the screwhead as you are drilling annd backs the screw out. There are also newer styles of srew exctactors that grab the outside of the screw head and usually those work well.

 

Have you a dremel? if your jis is stripped beyond use, you could cut a slot in the screw head and use the impact driver with a regular bit.
I had good luck with a pair if small Vice Grips , yes that brand as well.
but that would be last resort if Impact driver does not work, as you could snap the screw head off
if you have to soak them in a dish of pen oil.

 

Make sure the impact driver you use has JIS (Japanese Industrial Standard) bits as opposed to regular Phillips. Phillips is designed to torque out in order to prevent over tightening. This results in stripped heads. The JIS tip is a "plus" like the Phillips, but is straight cut, so no twisting out. All the screws on these bikes originally are JIS style.
Another option once you get them all out, is to switch all screws for hex head screws. They look cool!

 

The commonly available SAE impact drivers have bits that do double duty in that regard. I actualy used to use the impact driver bits all the time before I could afford a set of JIS screwdrivers.

 

explain how one holds a carb securely enough to use a impact driver on the "hat" screws

 

I had good luck with needle-nose vice grips in order to turn the screws. Be careful

 

i put the carb in a vise with wood jaws, clamp on the vise grips, find the right screwdriver, put my chin on the end of it to push down and keep it straight and rotate my whole body so the vise grips and the screwdriver turn in unison

 

Chin ?...why not one hand on screwdriver...one hand on vice grips..... When replacing screws, use anti-seize compound.....

 

Even a little and I mean little heat to help,one of those small butane torches. Just enough to make the aluminum expand to relieve pressure on screw and help penetrating oil do its job
A wet rag on carb body so heat won't spread.
Be careful using impact driver you can break the carb with too much force. Support the corner of carb body before you take a swing!

 

i find with with my hand on the top of the screwdriver with it giving the torque and my chin on top of my hand, pushing down i can look right down at the business end and can keep it straighter to the screw. once i get off axis things go bad.
i don't mind looking like a fool if it works

 

Since they're mildly stripped now, it may be too late for this tip:
When I had trouble with these, I did the usual soaking in penetrating oil, etc, etc, but I also put the screwdriver in the head and gave the driver handle a good couple of whacks with a hammer. My reasoning was that the screw was stuck due to corrosion, so sending a shockwave through it with a hammer strike might be enough to break it up to the point of getting the screws out. It worked for me. About half the screws on my carb hats wanted to strip prior to this trick, and afterwards they all came out with what I would call "normal" force.

 

A bit of valve lapping compound on the tip of the screwdriver wil and some grip to the screw.

 

try tightening the screw just a bit, it will break the threads free.

 

One builds a fixture out of wood.

 

Invest in some good screwdrivers or these bits from Snap-On with the small ridges on each face to grip screws.
They are magic
Part # SDM2221RB #2 or smaller
SDM2211RB. #1

 

of course, you have wood vise jaws, maple or oak. then there's aluminum and rubber ones too. and the little tool makers vise that you put in the big vise

 

It seems that you have been snooping around in my garage lol

I meant to quote this post of yours.

Hence the refrence to building a fixture. Anything that I think might break gets some extra care. A bit of oak to support the casting underneath the screws goes a long way towards not breaking things.