Multiple screws snapped inside the block

How cooked am I? For context I bought my kz650 from an idiot teenager that knew zero about bikes. It was also junkyard quality but I took on the challenge of bringing it back. It's almost done now, 2+ years later and after buying a replacement sprocket cover I now know why the original was lost to time. They snapped 4 of the 5 screws that holds the cover on into the crankcase. I've tried alot to remove them with no luck. What do I do? I'd ride with no cover but you need the cover to actuate the clutch plus safety or whatever but mainly the clutch. I'm attaching photos, if anyone has any suggestions or ideas I'm all ears. And no a new engine, crankcase, or anything in between is not on the table. I've spent well past what the bike is worth at this point.

Personally I would drill out and tap new threads,
Rich.
 

I've tried but all the snaps arent clean. They are at weird angles that make the drill bit wander. Also the original screws are hard alloy that apparently dulls 75% of drill bits.

That's what they make cobalt drill bits for.

Use a center punch in the middle of the busted screw and make a dimple.  Drill a small hole in the screw, and work the drill bit sideways as needed until the hole is dead center.  Then move up to the next size drill.  Using left hand drill bits works well.  When the old screw is just a shell, it will likely spin out when drilling.

I would probably pull the engine, dismantle it and use a drill press.

hardrockminer wrote:

I would probably pull the engine, dismantle it and use a drill press.


 

I think based on what OP has said, he doesnt want to do this. I personally have gone through what OP has said before but for the injector bolts on my cars cylinder head. It was not a fun experience but for something like this there is generally a low risk. I would helicoil or tap threaded inserts into the holes. You probably aren't going to be able to get the drill straight, its just a part of the game. I dont think its even worth it to try to ez-out the screws, just drill through them. It's not pretty.     

Hold a nut over the end of the broken screw and weld fill the nut center to the snapped screw. The heat from the weld will break the galvanic corrosion and then simply use a spanner to unscrew it. 
might take a couple of attempts but you wont be in danger of trashing the engine case.

This might have to be the move. 

youtube.com/shorts/iUkCrgZ94pY?is=DBBDwJCKAQn36qXu

Here’s what I did on my 650 when I snapped
bolts off in the trans door cover.  The weld filler won’t stick to the aluminum, just the broken screw and nut.

Later, Doug 

bound wrote:

hardrockminer wrote:

I would probably pull the engine, dismantle it and use a drill press.



 

I think based on what OP has said, he doesnt want to do this. I personally have gone through what OP has said before but for the injector bolts on my cars cylinder head. It was not a fun experience but for something like this there is generally a low risk. I would helicoil or tap threaded inserts into the holes. You probably aren't going to be able to get the drill straight, its just a part of the game. I dont think its even worth it to try to ez-out the screws, just drill through them. It's not pretty. 

 

 

What I read was no to a new engine or crankcase.  It takes some work to pull and dismantle the engine but it would preserve the existing holes.  But if you can weld then I like Doug's solution best.

hardrockminer wrote:

bound wrote:

hardrockminer wrote:

I would probably pull the engine, dismantle it and use a drill press.





 

I think based on what OP has said, he doesnt want to do this. I personally have gone through what OP has said before but for the injector bolts on my cars cylinder head. It was not a fun experience but for something like this there is generally a low risk. I would helicoil or tap threaded inserts into the holes. You probably aren't going to be able to get the drill straight, its just a part of the game. I dont think its even worth it to try to ez-out the screws, just drill through them. It's not pretty. 

 

 

What I read was no to a new engine or crankcase.  It takes some work to pull and dismantle the engine but it would preserve the existing holes.  But if you can weld then I like Doug's solution best.

Yes i agree dougs solution is the best if there is access to a welder. The only thing that would suck about dismantling the engine is lots of time and money for gaskets. Broken bolts suck, no way around it.

The worst thing is a broken tap in one of those cover holes.