Broken bolt at reed valve cover - can we review do's and don'ts for removing? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 18 (permalink) Old 02-15-2009, 07:35 PM Thread Starter
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Angry Broken bolt at reed valve cover - can we review do's and don'ts for removing?

First, can I just vent for a second and say how much I hate those soft aluminum bolts that Kaw uses on the engine block? They have an amazing tendency to stick-and-snap-off on the reed valve covers - guess it's the heat, crud from the exhaust, but they are just consistently a problem and I see no reason why four steel bolts couldn't have been used instead. 'Nuf said.

Anyway, I broke off the bolts when I was rebuilding Orleans (fixed 'em with JB Weld..sort of) and I've done it again on this new project bike. There's about 5mm of the threads sticking out from the engine, and I've been hitting it all weekend with PB Blaster. My guess is that when I go to turn it, however, it's just going to snap off closer in, so I bought a 6mm drill bit and a M6 x 1.0 tap to clean the threads when it comes to that.

That said, can someone walk me through the steps to drilling out the remaining bolt bit and cleaning the threads? I know I don't have much margin for error since I'm in the engine case...but any tips before I start drilling would be greatly appreciated.

Thanks in advance.

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post #2 of 18 (permalink) Old 02-15-2009, 07:55 PM
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I just had to drill out the manifold stud and tap it to put my Jardines on. Looking at the bike I'd say you are fairly safe because you have the reed valve to keep any debris from going into the engine. Use oil (regular 3-in-1 will work) and drill in a little and back out to clear the debris. You might want to have a small vac available and suck out the shavings. Once you get it cleaned out, tapping it should be fairly easy. Line the tap up square to the hole and start the tap going in a little, then back out to clean out the debris and go again. Use lots of oil to help the tap cut the metal.

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post #3 of 18 (permalink) Old 02-15-2009, 08:13 PM
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Sometimes it helps to have an assistant line up the drill bit and tap horizontally and vertically while you're working so things stay square.

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post #4 of 18 (permalink) Old 02-16-2009, 04:34 AM
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Don't forget to put some "anti-seize" on the new bolts...
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post #5 of 18 (permalink) Old 02-16-2009, 07:00 AM
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Originally Posted by 750Doug View Post
Don't forget to put some "anti-seize" on the new bolts...
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post #6 of 18 (permalink) Old 02-16-2009, 07:23 AM
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post #7 of 18 (permalink) Old 02-16-2009, 10:29 AM
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File the top flat. Use a center punch to dimple it in the center. Drill as suggested above. BTW they do make drills that turn CCW that could actually remove the broken piece while you drill. Start with a very small drill then go tone large enough for an easy out. In a pinch a small torx bit can be hammered into the stud to pull it.

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post #8 of 18 (permalink) Old 02-16-2009, 01:12 PM
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I've used screw/bolt extractors in the past with very good results. If it works (never had a case where it did not), then existing threads will not be damaged. No tapping needed, just buy a new bolt in the same size as the old.

You can find bolt extractors in most hardware stores, in all sizes and they are about the cost of a good drill bit (I picked up a kit with about 6 different sizes for about $20). Extractors are simple to use; apply penetrating oil (let it work in real good), drill a hole in the center of the broken bolt, screw in the bolt extractor (correct size to fit in the hole drilled) and use a breaker bar (or wrench with a pipe to extend the handle) to unscrew the broken bolt. The extractor has left hand/reverse threads, so it continues to bite into the broken bolt as you unscrew it.

Chris Glennon - Portland, OR

Last edited by cglennon; 02-16-2009 at 01:19 PM. Reason: more detail
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post #9 of 18 (permalink) Old 02-16-2009, 06:06 PM
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I've seen something called Grabit advertised on TV for use in removing stripped / snapped screws. I don't own a set, and have no idea whether it works as well as advertised, but it seems so that it'd be useful in your situation.


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post #10 of 18 (permalink) Old 02-16-2009, 10:37 PM
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i normally try to grab it the bolt w/ vice grips and use some heat to get a bolt out, if that doesnt work ill either try to drill w/ a left handed bit and/or use a easy out, if not i weld a nut to it.... all else fails drill and tap. if u weld a nut to it it'll either work or it'll break off closer and it'll be harder to drill

1990 Kawasaki Vulcan 750

.... slightly modified
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