Stripped screws

Just a quick question;

Does anyone know if the manufacturer used threadlock or something like it to keep the screws in the carb holders well kept in place? I'm trying to get those screws off so I can replace the holders, and I've already stripped two screws trying. (got one of the buggers!) Thanks,

Cody

Screws are steel and cylinder head is aluminum. With some heat, a process called "galling" takes place. Galling works a lot like thread locker. It makes the screws stick as you have already figured out. I don't think any locking agent was used.

In any case, buy a GOOD QUALITY impact driver with the correct sized phillips head bits. A good quality driver will have #1, #2 and #3 bits. I "THINK" the phillips head screws holding the carb intake manifolds are #2 but test fit to be double sure. If you don't have enough room for a driver to get in there, use vise grips to break the screw loose. You might apply some heat first to ensure you don't bust off the head.

When you reinstall your new intake manifolds, or put the old ones back on, use a 6mm blind bore tap to chase the threads (clean them and restore them) and then spray some carb cleaner into the hole and blow them out with compressed air prior to installing NEW fasteners. I would definitely use socket head bolts (stainless) or zinc plated steel. DO NOT use the dark colored socket head bolts available at most auto parts stores. They rust like all get out.

The holes will be 6mm with 1.0 pitch. Use a blind bore tap (flat on end) to chase the thread.

sometimes on these older motors, if you can get one screw out, then you can twist the boot counter clockwise and it will loosten the other screw.

As the post above says, use allens when you put it back together.

Jay

www.kzzone.com

You need to give the screws a good shot of Kroil and let it sit overnight. I replaced mine this summer. They had never been removed since my bike was built (it's a 77 kz650C1) and thanks to Kroil they came out with no problem and did not require an impact driver. Good luck, Ed

Oooh... quite a few good suggestions here... I tried to get mine off on the 400 this summer and gave up... :S

Hey 650ed, where do you get "Kroil", and how come I never heard of it before?

I bought a 1/2 pint can directly from KANO, but Brownell's and other firearms parts places sell it too. A little goes a long way. Here's their site:

www.kanolabs.com

Their order form shows all the sizes and prices. Ed

watch out their, i went to replace the boots on my kz1000a and snapped one off, hand to drill it and put an insert in it. they were a b--ch to remove. i had to use my small vicegrips to remove six of them. but now its all done with new boots and no problems and replaced all the screws with allen head ones. good luck.

Side note on the Kroil... it is good stuff but hard to find sometimes. A good alternative is PB Blaster. It is available a Walmart and a can is standard equipment in my shop. Works the same as Kroil and here in Texas Hill Country is easy to find since I can find my Walmart! bwhahaha

Just out of curiosity when you reinstall the bolts would it be a good idea to use anti-sieze or not? I'm basing my question on the fact that anytime we use steel screws or bolts in aluminum holes on aircraft we use anti-sieze on them. It works good on aircraft. But since no one had mentioned it in this thread I thought maybe there's a reason not to use it here?:huh:

Thanks to everyone, I got those screws out and replaced them without any trouble.

Don't know what the "text book" answer is, but I use copper grease. A lot of fastners being replaced by stainless, and stainless usually galls even faster/worse than normal steel. I suppose the galling could serve a purpose, the purpose being to avoid using nylocs, locking washers etc - you can rely on stuff rusting and galling instead.

Bud1 wrote:

Just out of curiosity when you reinstall the bolts would it be a good idea to use anti-sieze or not? I'm basing my question on the fact that anytime we use steel screws or bolts in aluminum holes on aircraft we use anti-sieze on them. It works good on aircraft. But since no one had mentioned it in this thread I thought maybe there's a reason not to use it here?:huh:

When I get a "new to me" engine in my shop, and am going to be rebuilding, I remove all case coverold bolts and toss them and use stainless socket head bolts. I also clean all the holes. Use carburetor cleaner and compressed air and chase any that have left material on the bolt that was moved using a tap. I have not found it necessary to use anti-seize compound.