Two broken starter bolts on a 81 CSR 750 twin

Wondering if there is any way to get these two bolts out with the engine in the bike? I have hit them with BP and these is maybe 1/4" of them sticking out of the engine block. Taking a look at it and if I can't get them loose with BP, Heat and tapping them with a center punch to see if I can loosen them up,

Starter is off the bike, so I can at least see and or work on them.

Any suggestions would be great. Not looking forward to pulling the engine so I can get a direct shot at both those bolts. But if I have to, I have to.

Thanks in advance.

Pic of the bolts?
Steve

I will get them posted soon, sorry Steve...I know that will help a lot.

No problem, where are they?
Steve

If you have a 1/4" sticking out above the surface one of my favorite fixes is to get a thin nut, one size larger than the broken bolt (6mm bolt, grab a 5/16 nut) and weld that sucker to the bolt shank. Gives you tons of concentrated heat, and a gripping surface MADE for tools

That is something I have not tried but sounds like a GREAT idea. I will have to give that a try. I will post some pics as well.

So gave this a try and it seemed like it would work. Tried a few different ways, washers to build the weld on the broken bolt and then even a bolt welded onto the broken bolt. It all ended with the bolts in the starter breaking again. When I get time I will pull the motor and get at this.

Thanks for the info, I am sure it will work if you had a little more bolt to work with. This bike is a 1981 and she was outside for a long time. Just picked it up with a few other bikes and thought I would see what I can get working.

Before I pull the motor out of the frame of the CSR, drill and tap the stater bolts, I went to work on the other KZ750 twin engine. Took the head off and cleaned the tops of the pistons. I then pored some Mystery oil in the top of the pistons enough to fill around the rings well. I let is sit for a good couple of house. Well nothing moved. Cleaned up the pistons and then pulled the jugs off, or tried to. Got them elevated about three inches and then tried to turn it over. There is something very stuck of broken in there.

I will be taking that engine apart later on, for now I am stealing parts of off it be able to put the CSR engine into the KZ750 B's frame. I think and or hope just the different valve cover.

The starter clutch was also very lose as they all seem to be. The springs were all in good shape and nothing was broken. I will see how the CSR starter clutch is and make them work.

Got the carbs cleaned today. Rust and normal nasty green sludge left over. A lot of B-12 chem cleaner, Q tips, compressed air and some carb dip and they look much better. Need to finish them up and then bench sync them before I put them on the CSR. I did remove the old inlet carb boots from the head of the CSR and replaced them with the 77's boots, they seem to be a perfect match.

I will have to make some block off plates for the emissions as that is not staying. Should be able to see if she runs in the next few days. The frame on this bike is really weathered compared to the 78 frame I have, but I might just stick with this setup and work on cleaning up the frame.

After seeing a post on the back brake damage on one of the other CSR's I will really have to check that out. I do have the parts to change it over to a disk setup...first things first, will it run?

Maybe take a 1 by 2 piece of wood and gently tap on the pistons to try and free them up and when trying to turn over the engine make sure you don't have the cam chain bunched up on the crank.

Dang it!
That is a great trick and I've used it a few times with success but those bolt remains, especially that bottom one, were heavily oxidized. Looks like it rusted looong ago, so it's likely to have been weakened, leading to the continued breaking...
Your welds looked good. I was expecting to see the last pic being a"success!" pic.
In my experiences, when the fasteners are that oxidized, you have to really work them a ton with lots of PB soaking for hours if not days even when you do weld a grip-nut onto them. Still have to squeak the borked bolt back 'n forth a bagillion times to get the oil down the threads far enough.
Glad you're a patient guy. I bet it's nice to have a couple of compatible bikes to work with.

Timbox wrote: So gave this a try and it seemed like it would work. Tried a few different ways, washers to build the weld on the broken bolt and then even a bolt welded onto the broken bolt. It all ended with the bolts in the starter breaking again. When I get time I will pull the motor and get at this.

Thanks for the info, I am sure it will work if you had a little more bolt to work with. This bike is a 1981 and she was outside for a long time. Just picked it up with a few other bikes and thought I would see what I can get working.

Looks like the best way would be disassemble, drill, tig weld and retap. I assume the bolts may hold the case together. If they do that sucks more. You may be better off with a used engine. R