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Discussion Starter #1
I am working on 650 carbs where the machine screws that hold the carb body mounting plates. They will not give up. Next step Is to apply heat. Some are going to need replacement. I see sets on eBay with Allen heads made of stainless. I am afraid if I put th the kind of pressure on stainless as I put on the steel screws I would have turn them off.

Anyway any advice on stainless or oem screws.

Once I get these out I will put a little blue locktite on the replacements to act antisieze.

By the way one throttle needle is bent. I got an exact replacement used. It is stamped with 64E. Are all the CX 500 and CX650’ s th same?
 

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I can't offer much help. Only a suggestion.
Apply the heat to the housing, not the screw. Hopefully, the housing will expand and loosen the grip on the screw.

Depending on the SS alloy and the housing alloy, you may be dealing with galvanic corrosion locking the screw in place.

FWIW. SS screws are not strong screws. If you are successful with the removal and decide to replace with SS screw be sure to reduce the torque requirements. This will also reduce the clamp load, I would not reduced the clamp load on gasket joints or pressure joints.

Another trick that may work is to use an orbital sander to vibrate the tool removing the screw. More or less to "shake" the screw loose.
 

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Are you using a JIS screwdriver or are you trying to remove the screws with a Phillips driver?
 

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Like relic said, if the screw head looks like a phillips but has a little round dimple/indent on the head it is a JIS (Japanese Industrial Standard) screw and will strip out rather easily if you are using a phillips screwdriver. Here is a link to the screw driver i got from amazon that looks like a regular screwdriver but it's also an impact driver and it worked on my carburetor screws https://www.amazon.com/Vessel-Megadora-Impacta-P2x100-Screwdriver/dp/B003BI8HHQ/ref=sr_1_12?keywords=jis+screwdriver&qid=1579806602&sr=8-12

Cheers and good luck
 

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Discussion Starter #6
No I am using a JIS screw driver. I am in Florida for the winter and did not bring my carb rebuilding tools. I need to get a little propane torch and some JIS bits for an impact driver. I can grab the heads of the larger screws with a pair of pliers and still can’t get them loose.

However it does appear that the larger screws holding one of the brackets are phillips. Go figure.

Anyone know what number stamped of the jet needle of a CX500 carb is?
 

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Have you tried applying PB Blaster to the fasteners? If not i would actually spray it on and repeat the process over a couple of days, may help loosen it up. I've done that on fasteners on cars before and have had good success with it.
 

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Fatboy, do you have a bench vise to hold carbs, if yes one trick I learned on Chevy 440 t4 transmissions that have a torx screw that gets so tight it strips out the torx splines out ,is to take a pin punch slightly bigger then the head of the screw , and my favorite 24oz ballpeen and a sharp smack on the head of the screw. Support the other end of the carb as not to break it from hammering on it. This also sometimes fixes the head of the jis screw.
 

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Discussion Starter #10
Problem solved. The last guy who did the rebuild used red loctite. A little heat and everything came apart with almost no effort.
 

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Good catch on your part, stupid idea on the POs part...
 

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Perhaps the PO used the wrong strength of Loctite.

There are many strengths of Loctite. Blue Loctite would probably be a good choice for this application.

Sounds like the PO used the red Loctite (permanent) strength which requires heat to release. Typically, the red Loctite is used for Grade 8 bolts. Anything less than a Grade 8 bolt will shear before the red Loctite releases, this is when heat is used.
 
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