Thunderbolt 800 Carb Rebuild Issues

[hartleck]

I'm in the middle of re-kitting my Thunderbolt 800 Carbs and have encountered a problem. Whoever worked on these carbs previously must have used gasket seal on everything. The gasket seal material was found inside and out on these carbs. That really isn't the problem however. The real issue is the brass screw heads on the Main Nozzle Plug Screw and the Body Channel Plug Screw. I have tried everything I know to get them loose short of inflicting more damage than is already evident. A flat tip screwdriver will not break them loose without further gouging out the heads. It appears these were even put in with gasket seal as you can see in the pictures. I have only worked on the first carb but the second appears to have the same issues as the pictures show. Any ideas of what I should try next?

 

[Wingedwheel]

Re: Thunderbolt 800 Carb Rebuild Issues

Wow, sometimes its hard to believe what people will do. You might try soaking them in a solvent like MEK or Acetone. Just be aware that it will also dissolve any rubber parts in the carb so you might just set it up where only the screw head is soaking in it. I hope that helps.

 

[Moody Blue]

Re: Thunderbolt 800 Carb Rebuild Issues

That is pretty typical of the repair attempts on those carbs. The sealant/thread locker that Merc used was very effective.

You will need to use the largest possible screwdriver that will fit the slot EXACTLY. If necessary, grind an existing screwdriver to the perfect size. At this point I would take a small jewelers file and "square up" the slots on the screws then use a bigger screwdriver.

Another thing I've found effective is to use a small butane torch and carefully heat the area up to soften the sealant. While still hot, use the proper screwdriver, and apply lots of down pressure while trying to unscrew. Proper screwdriver size is the key, can't stress that enough.

 

[richardcranium]

Re: Thunderbolt 800 Carb Rebuild Issues

That is pretty typical of the repair attempts on those carbs. The sealant/thread locker that Merc used was very effective.

You will need to use the largest possible screwdriver that will fit the slot EXACTLY. If necessary, grind an existing screwdriver to the perfect size. At this point I would take a small jewelers file and "square up" the slots on the screws then use a bigger screwdriver.

Another thing I've found effective is to use a small butane torch and carefully heat the area up to soften the sealant. While still hot, use the proper screwdriver, and apply lots of down pressure while trying to unscrew. Proper screwdriver size is the key, can't stress that enough.

Good advice on the heating point. The only thing I would add is to heat the alloy not the screw, it will aid your cause by expanding around the screw, thus hopefully loosening it.

 

[hartleck]

Re: Thunderbolt 800 Carb Rebuild Issues

That is pretty typical of the repair attempts on those carbs. The sealant/thread locker that Merc used was very effective.

You will need to use the largest possible screwdriver that will fit the slot EXACTLY. If necessary, grind an existing screwdriver to the perfect size. At this point I would take a small jewelers file and "square up" the slots on the screws then use a bigger screwdriver.

Another thing I've found effective is to use a small butane torch and carefully heat the area up to soften the sealant. While still hot, use the proper screwdriver, and apply lots of down pressure while trying to unscrew. Proper screwdriver size is the key, can't stress that enough.

Moody B. Thanks again for the help. mission accomplished, Now to a new post. Thanks again!