KZ650 Broken Engine Cover Bolts

[Guest]

When I was taking the sprocket cover off to change the sprockets, one bolt broke off (lower left bolt) and one was missing because it had been broken off at some point in the past (lower right bolt). I thought, "No big deal, I'll just use a bolt extractor on those." Nope, I just made the problem worse on the one I broke by drilling it into a concave shape inside the thread. The other one looked like somebody tried to drill it out but just left the sides of the bolt still in the thread, so I didn't even try. Any bolt extraction tips?

[chuck hahn]

Weld wont stick to aluminum. Clean the bolt shaft with acetone to get any oil off and start in the center and lay some weld to the bolt..little spurt..then another till theres a little bead to get some good weld to. Stop and let it cool till the red is gone and keep working the bead out so you have something to grab with the vice grips. MIG will be better than stick ARC welder.

The heat will break the crud ( and possibly the thread locker thats in there ) up. May get a little pitting on the flat of the case but thats not a because thats just where the cover rest against the case. I use this all the time to get broke off exhaust studs out.

See my signature....I have the same bike.

[chuck hahn]

And a little tip...let the weld harden for about 5 minutes before trying to twist. The heat will still be there and a drop of oil to wick into the threads wont hurt either. May smoke so have some ventilation around.

[Nessism]

I'd drill out the broken bolt. Try to get a center punch on the center of the broken nub then start with a small bit. If the hole winds up off center take your drill and work it around to try to center the hole and then go up one bit size. Continue drilling progressively larger and working the drill to make sure you stay centered. Left hand bits work best because at some point during the drilling the remaining portion of the bolt usually spins out. Worst case, work until you get to the tap size and then switch over to a tap and clean the threads out that way. Worst case again, you helicoil the engine case with new threads.

[chuck hahn]

And what if he ruins the threads Ed? What if he drills thru to the inside of the case? I use the welder method first and it usually works. drilling and chancing fluccking it all to he!! is a measure of last resort if you ask me.

[Nessism]

And what if he ruins the threads Ed? What if he drills thru to the inside of the case? I use the welder method first and it usually works. drilling and chancing fluccking it all to he!! is a measure of last resort if you ask me.

Chuck, Look at the photo. How do you propose welding onto a nub that's already sitting below the case surface?

[chuck hahn]

Same way I do it all the time on exhaust studs and I described!!!!!! Start on the center of the bolt and lay a heavy spot weld..yes down into the hole. The weld wont stick to the aluminum and you keep laying on another heavy spot weld and then another and another till its built out past the surface and you can grab it with vice grips. I think I have pics in my photobucket but itb takes a week for the site to load these days. I will try to be patient enough and go see if I can retrieve some for you.

[chuck hahn]

OK. I am not wading thru 948 pics on a half broke computer and a slow as he!!! pay to advertise site. But I assure you I have removed exhaust studs broke off 1/8 inch below then face and it works excellent 90% or better. Just lay in a heavy bead and let cool a minute and lay on another. keep repeating till its extended far enough to grip and twist. once it moves, twist in and out and apply more oil. This grind up the corrosion and works the oil deeper into the threads.

Be patient and work at it with some finesse.

[JTGS850GL]

Yep, should be no problem building a bead above the surface. The weld will build on the steel bolt but will not stick to the aluminum. I may pit the aluminum surface but will not weld it self to it.

[chuck hahn]

And where the bolt is has no significant importance other than its in the boss for the bolt itself, so if the weld does pit it or even melt an edge it doesnt matter. The back side of the cover just rests against the shoulder..no biggy.

[clutchthirty]

Well, bad news. I tried progressively drilling it out to use a bolt extractor, which I have had success with in the past. All was going well until I heard a snap... The entire bolt mount had broken off the engine case. Is this old aluminum really soft? I wasn't applying much pressure.

Anyway, now I think I will be taking a drive to the machine shop. Any guesses on whether they'll be able to weld a new thread housing on there for me? Feeling very deflated over this silly broken bolt that is turning into a disaster. Makes me very reticent to take the valve cover off to adjust the valves (are those bolts going to break too???) IMG_2054.jpg

[chuck hahn]

If you have the piece take it with you. Have them weld it on and FILL THE HOLE. Why fill the hole you are asking yourself..right? By filling the hole after they weld the outer part on your creating a new solid boss as it came out of casting with little to no chance of it being cracked. At this point you can set the cover on and mark the spot to redrill a brand new hole and tap it. This ensure two things..1) the repair is solid and strong and 2) the threads are aligned right since youve retapped them and the bolt will not reseize from being jammed in.

I take it the old bolt stock is now removed??? If so, hold the piece up to the case and get a depth for how to retap once repaired.

[chuck hahn]

As for the valve cover. Crack all the bolts loose before removing any of them so side stress isnt a factor in wedging anything up. Once they are cracked loose a little penetrating oil will run down the shafts and into the threads. Work the bolts in and out a little to get things moving and you shouldnt have any problems.

And I will say this for the 100,000th time for anyone else reading this thread. THROW THOSE PIECE OF CHIT EZ OUTS IN THE TRASH AND NEVER USE THEM AGAIN.....PERIOD!!!!!!!!!!

[mikerophone]

Man - that's a bummer. Crazy how it broke like that.

Personally, I've had minimal success with EZ outs on things like this. Last time I broke TWO off getting exhaust manifold bolts broken off in the head of an accord I swore I'd never use them again. Left handed drill bits all the way for me.

Since we're both in SLC, would you mind letting know what machine shop you use and how it works out?

I've used Love on 1700 S. in the past (sounds like a woman's special friend "The Love Machine Co" hahaha!) for heads in the past but no idea if they do this kind of thing. I've also used another shop in that area to press bushings out and in on LCA's on my old Passat back in the 90's but I can't for the life of me remember the name.

[clutchthirty]

Thanks for the advice Chuck. I've used bolt extractors before and never had a problem, but I will avoid them on the motorcycles now. The threaded part broke into several pieces so I don't think having them weld it back on is going to be an option. I wonder if they will be able to weld a nut or something on there?

Everyone I've talked to has said to use Lindsey Machine, they're in Sandy. I'll give them a call sometime this week to see what they say and will maybe trailer it down when I get the front wheel mounted back up.