(Almost) Stripped Fuel Flow Screw

[moneymonk]

Hi. Thanks in advance for your help.

I'm a learning mechanic, and last spring bought a good looking 1982 GS750TZ that I want to get running smoothly. The previous owner said he "just had it running" but it needed a battery. After a whole summer of overcoming issue after issue, now it seems that the problem is that the #1 Cylinder is not getting any go-go juice. The guy who owned the bike before me torqued the Fuel Flow Screw (referred to as the Pilot Air Screw in your carb cleaner guide) on the #1 carb closed and then mostly stripped it trying to open it again. I haven't helped matters any by monkeying with it eather. At any rate, I've already invested so much time and money into getting this bike street-worthy (battery, plugs, tires, chain and sprockets, coils, some electrical work, a gasket or two), I really don't want to invest in a new carb or a mechanic to drill out the bad screw. I've come SO far and I'm SO SO close. My wife wants me to build a deck this summer, so if i can't find a cheap way to get it rolling, the bike will have to sit another year while my loot and effort gets invested elsewhere. I just need to loosen it like 2 or 3 (or 4) turns to get my cylinder some gas.

Take a look at the pic, I hope it isn't too fuzzy.

Please help.

Thanks again-
Monk

[bradleymaynar]

Get a set of EZ-outs. You should be able to remove the bad screw without having to tap a hole into it (it worked for me). Then you'll probably have to go to a Suzuki dealer to pick up a new screw. Unfortunately, I believe they only offer it with the spring. I think the price was around $35.

Brad bt

[salty_monk]

Have you tried an impact driver & a big hammer on it? Put lots of penetrating oil in there too...

Can you put heat on there or are there any O rings close that might melt? If so maybe freeze spray will do it.

Dan

[49er]

Hi. Thanks in advance for your help.

I'm a learning mechanic, and last spring bought a good looking 1982 GS750TZ that I want to get running smoothly. The previous owner said he "just had it running" but it needed a battery. After a whole summer of overcoming issue after issue, now it seems that the problem is that the #1 Cylinder is not getting any go-go juice. The guy who owned the bike before me torqued the Fuel Flow Screw (referred to as the Pilot Air Screw in your carb cleaner guide) on the #1 carb closed and then mostly stripped it trying to open it again. I haven't helped matters any by monkeying with it eather. At any rate, I've already invested so much time and money into getting this bike street-worthy (battery, plugs, tires, chain and sprockets, coils, some electrical work, a gasket or two), I really don't want to invest in a new carb or a mechanic to drill out the bad screw. I've come SO far and I'm SO SO close. My wife wants me to build a deck this summer, so if i can't find a cheap way to get it rolling, the bike will have to sit another year while my loot and effort gets invested elsewhere. I just need to loosen it like 2 or 3 (or 4) turns to get my cylinder some gas.

Take a look at the pic, I hope it isn't too fuzzy.

Please help.

Thanks again-
Monk

It's not clear in your pic whether you have removed all the paint/sealant from around the screw thread and aluminium. If not, use a sharp pointed instrument such as the point on a set of dividers, or an engineers scriber to scrape out the paint completely.
Spray in penetrating fluid and leave to soak overnight.
Now carefully use an impact driver, making sure that the blade head is not wider the the screw slot or you well further damage the carb body. The brass and surrounding aluminium are soft, so dont get to agressive with the hammer.
If still no joy, an easy out is your next move.

[bradleymaynar]

The only problem with using an impact screwdriver, for me, was that the bits were a larger diameter than the hole for the mixture screw. Regardless of how it comes out, since the head is probably stripped, you'd be better off to replace it.

Brad bt

[salty_monk]

If you can't find the right impact bit get one ground down... You could do it yourself with an angle grinder at a push or even with a file (but it will be blunt when you've finished).

Dan

[Big T]

The important questions are:

1. Did it get harder and harder to turn, so you applied more force?
2. Does it turn in?

If so, use some carb cleaner to soften the paint, then clean out as much of the paint as you can. Turn it in 1/2 turn, then out 1 turn. Repeat, cleaning out any paint that appears. Some penetrating oil may be necessary.

These screws should turn out pretty easily. It's the paint that causes the problems

[Delbert24]

Let me know when you get it out.I believe I may be able to get the screw.
Thanks,
del

[moneymonk]

Thanks for all of your suggestions. I understand that I'll probably have to shell out for a new screw. The screw I won't accept is the one from my local bike shop. Quoted at $240 parts and labor.

I don't think there is any paint or sealant in the way. At least not on top, though it appears that the threads above the screw have been destroyed by too big screwdrivers turning inside the opening.

Like bradleymaynar, my problem has been finding a bit that is narrow enough to fit into the carb body, yet fat enough to fill the slot in the screw without further stripping. The edges of the slot in the screw are rounded so it 's hard to get a grip in there. So, in response to Big T, I don't think I can turn the screw in, but I'll try that. I have an impact driver with a standard bit, but it's WAY to big for the job.

What does EZ-outs do?

Thanks again.

Monk

[psyguy]

What does EZ-outs do?

Thanks again.

Monk

easy out is like a reverse threaded drill bit
you drill a pilot hole and then insert the easy out bit in and turn out
they are very hard yet brittle so need to be careful not to apply too much torque
but should be ok for your application in soft materials!

if you end up stripping the thread you can use heli-coil inserts to bring the thread back to the original size

[moneymonk]

Hey Delbert24-

I'm going to try to get this fixed this week. Where did you find the screw? Online, or brick & mortar establishment?
I know my carbs are Mikuni, but I'm not sure what model, how do I know I'm getting the right screw?
Let me know so we can eather work something out where I can purchase it from you, or where I can find one online. I really appreciate everyone's assistance. This is a really great group.

Thanks-
Monk

[bradleymaynar]

What I did to remove the stubborn screw. I went to Harbor Freight and picked up a set of small EZ-outs (screw extractors). I then used one of the smaller extractors and centered it as best as possible on the mixture screw head. I then tightened it (which is opposite of tightening a normal thread screw) and slowly worked out the mixture screw. The metal of the mixture screw is soft enough that you shouldn't have to drill a pilot hole. I didn't need to. However, you may want to let some penetrating oil, like PB Blaster, soak on it overnight.

Brad bt

[Norseman]

Pilot Screw Stuck

I had two of four pilot screws frozen in place with damaged heads on my GS650GLX. My method that worked great was to mount them straight in my drill press, use a small bit to drill a pilot hole after making a dimple for bit guide in the screw head. I then started the EZ-Out, applied PB Blaster, letting it soak overnight, and applied a little heat with propane torch at its lowest setting just waving it back and forth on the outside of the screw channel, just enough to heat the aluminum body up to expand, then slowly just backed the screws out. It took patience and care. One came straight out, the other took repetitive cycles of PB and heat, but after four or five attempts, it surrendered.

You can get replacement screws with screw, washer, o-ring, and spring from http://www.motorcyclecarbs.com/. I called them and they were quite helpful - I received the replacement screws in four days, and I believe they were $14.95 ea.

Hope this helps,
Norseman