material composition of head?

I have a 80 xj650, is the head made of aluminum? The section that protrudes from exhaust side of my head cracked off right where the valve cover gasket bolt threads. I have another head I was thinking about cutting the section off it and either welding or using jb weld to attach that in its place because oil is leaking.

 

it is an aluminum alloy

 

You may find like me that replacing the head with a good used part makes more sense.

I had an exhaust stud snap- then snapped an ez out trying to extract it. After THAT, there wasn't enough of a boss left to drill. Shop brazed in a threaded nut, which broke out after a year.

Rather than try again, I looked at heads on ebay. I found a good complete head (assembled head, including, cams, caps and valvecover) for $109 shipped.

I paid another $80ish for a top end gasket kit and $35 on valveshims to bring clearances on the ebay head in line. Just swapped it on last weekend and it runs like a dream with no more busted up head and fixes that I hope take.

 

I actually got this one on eBay, when it came in a didn't take much time to look it over and just set it aside now it's too late. At this point I kinda just want to see if it will work.

I didn't even think about brazing. I've only done that on copper water heaters but it seems that could work for me

 

Did a little bit more thinking about brazing and I've decided that's not the route I want to take as I'd have to disassemble the engine. I want to leave the engine on the bike so I'm going to try jb weld

 

Post a pic of the damage. JB Weld is a fine product, but not necessarily for repairing air cooled engine heads.

 

what host sight do you like to use for photos? Ill get some pictures when i take the valve cover off tomorrow or Thursday.

 

You can upload them directly with your post - see the "Upload a File" button right beside "Post Reply"

 

On a related note, I have 3 XJ750 heads, and every one is damaged in some manner. My primary bike's got a stripped valve cover bolt hole, one has a broken exhaust stud and the other has a broken intake manifold stud.

I'm going to try AvE's method:



For the bolts, obviously.

 

Been working a lot of OT lately, finally got some time to work on it tonight. Tonight I used an epoxy puddy to fill in the missing section that you can see in the pictures. I plan on tapping the hole to.
Side note, winters, I love that guy's videos! Smart melon farmer right there

 

I'd love to see how you do that, if you don't mind taking a few shots and writing things up along the way.

 

Sounds good I will. I just went to get started on working on the bolt hole when I noticed the chain guard on the front (exhaust) isn't seated properly, its sitting about an 8th of an inch high. When I push on it I can flex the plastic enough to make it level with the top of the head but its not seating properly. Any ideas on what might have caused the guide to move? Do you think its something I should be concerned about?

 

That's how it's supposed to sit; proud of the head. The valve cover does not contact it.

 

I have a 1980, I just discovered this recently by the vin (4h7). With the valve cover that I have there is a tab that contacts the guide.

 

Yep. It's supposed to do that too.

 

Instead of going out on a Friday night I decided to finish up this broken bolt issue. Im pretty happy with the results.

I used Quicksteel puddy epoxy to fix it. It was easy. Prepped the surface, kneaded the puddy and squished it onto the broken section. I used to ruler to keep the puddy parallel with the head.

I used a little too much. A mar on an air powered right angle grinder tore right through it. The only way to do this with the motor still on the bike was to work from underneath the bolt hole.

Once the epoxy was level with the body bottom of the bolt hole I just drilled and tapped. The bolt threaded right in.

While I was out there working I was thinking about the chain guard spacing and I think Im going to have to use a paper gasket instead of gasket maker. You guys are probably thinking well...obviously haha! I tried using gasket maker on the transmission and the shift lever wouldn't return, these engineers put some strict tolerances on their covers.

 

How'd you line up the bolt hole with the valve cover? Just great eyeballing?

I'd be terrified the bolt wouldn't thread in.

Also, endlessly impressed that the quicksteel putty stuff binds strong enough that this can be done at all.

Awesome!

 

Herm.

Could I use this stuff to fix my borked valve cover bolt hole? It's stripped, and has had a helicoil installed (then failed, as said helicoil is now attached to the bolt - just fill the now large hole, then use the valve cover as a guide to drill a new hole in the stuff, then tap threads into it? Or is this a profoundly dumb idea?

 

Well since half the Bolt hole was left and I was starting at the bottom I just kept a little pressure towards what was left of the Bolt hole and it guided it's self.

I will have to say this stuff is not that tough, I wouldn't use it in your situation. When it dries it has the consistency of dry wall mud. If I were you I definitely wouldn't use the puddy. What Ill use if this fails is liquid 2 part epoxy like JB weld. It's more like glass when it dries, much more rigid and homogeneous than puddy. Also I think since its liquid it'll sink into and bond much better. Probably the best bet would be fill the hole with the liquid epoxy, use the cover as a guide like you said, but I would drill it again after the cover is off then still use a helacoil. Im not sure how much tensile strength epoxy has, using a helacoil would decrease the psi put on the epoxy threads since the diameter is larger. I can assure you that puddy epoxy is not something I'd use in your case. The problem you're going to have though is since the head is on a slant the liquid epoxy won't dry nice and flat which may give you trouble when you drill it.

If you can get the head to be level when you fill the hole do that. If not then definitely torque some of the other bolts on the valve cover when you drill it out to keep the bit from wandering and pulling the cover out of place.

 

Use bearing retaining compound to hold the Helicoil in, unless the threads for the Helicoil have stripped out of the head too.

 

And one more option is a keensert if the damaged hole has enough material.