Saving a 1980 750 twin.

I have run into an issue with the upper engine mount and Im hoping to get some insight here. For some reason the mounts that bolt to the valve cover or don't even come close to lining up with the mounting holes. The same thing happened to me on my KZ400 when I rebuilt the top end. I ended up having to hog out 7mm on the mount plate holes on that to get it to bolt up.

I need to remake the head mounts on this 750 anyway because this is where the coil mounts and my aftermarket coil does not fit with the stock engine mounts. No problem, I can make a motor mount easy enough, but then I realize that the mating surface on the valve cover is not perpendicular to the bolt hole on the valve cover. The valve cover has about 5 degrees of draft on it so it can be cast but the mounting points were never machined flat. This causes me to believe that the reason the original mounts no longer fit is when they are torqued down they bend out of shape so once you remove them they no longer fit. The original mounts also have a ton of slop in them.

I was going to make some trick mounts out of aluminum plate, but now I don't know what to do. The original ones are stamped steel with this cheesy bend in them that probably helps deal with the fit issues. right now i see two routes of action. take the valve cover off, mill the mounting points flat and make the aluminum plates, or file out the existing motor mounts and mod them to accept the new coil, maybe weld in a washer to help take out the slop. Thoughts?

I've had this happen to me back when I was a car tech.
Some parts seem to shrink or stretch. I would've guessed something w/ the motor mounts, but this was a simple top end job... NO IDEA!

Did you try loosening all the mounts, jacking up the engine and put the mounts on?
Steve

I remade the motor mounts and oversized the bolts. to remove the factory slop. I dont deny that is probably playing a factor here. Now that there is no slop in the mounts i can't do as you described Steve. Most of the original motor mount holes were only .5-1mm out. the holes up top are 5-7mm out. Like i said the same exact thing happened to me on my kz400 and all i did was remove the head, so i dont think its the motor mounts alone. I think I will hack up the stock one to make them work so i can keep the ball rolling.

You know you need to remove the cam cover, remove the draft from the casting and make a proper set of aluminum mount plates! Make the mount plates look good like the front caliper and motor mount plates, do something cool with the coil mount and you will be happy! I have to do this same work to my 750B so it will be good to see what you come up with.
If you need a short term fix, McMaster sells metric spherical washers,that may help you deal with the draft angle problem.

You are absolutely right Jon, i should pull the valve cover and make the mounts properly, but my new mantra is "finish it, then sort the details" (well as much as I can :S ) my KZ1000 took forever because I let small things like this hang me up without knowing if it was worth all the effort. If this was more visible i might consider it but right now i think i will go an easier route. Thanks for pointing me to those spherical washers. I have never seen those before and they are super cool!

If i were to go the thick aluminum plate route would i need to do both sides? it seams like one mount to the valve cover would be enough.

Good question! I have been thinking about how to make this mount do the most for some time. I am going to try to make mine tie both frame tubes together and act as a mount for the coil. Two aluminum plates with two locator pins to make it a stable structure. There looks to be lots of slop in the stock parts to eliminate. I need to buy a large angle block to do this accurately. I'll try to post photos as I do this.

Got started on the muffler, ill let the pictures do the talkin. I need to decide on what style of end-cap I will turn out of aluminum.

FOXY:evil: I like the right hand one.
Steve

very nice work!

leon