Topic: Broke Timing Plate Crankcase Boss

[rickhl]

Hey guys, new to the forum and to motorcycles in general. I guess this is starting to show since I have successfully broken my crankcase.

I was trying to get my timing adjusted and followed some tips here: http://www.motorcycleproject.com/text/sohcign.html

I "peened" the bosses holding the timing plate since the spark firing mark would not align properly. This lead to me breaking the boss. Do you think this is a big issue or could I live with it like this? 

Also related to this:

The screw that holds the points gap for 1-4 is stripped. Where would the best place to replace that be? Was thinking of a normal hardware store.

This is a 1977 CB750K7 btw.

[Bodi]

If it's only the screw - the threads in the plate are OK - a hardware store might have something but it's unlikely IMO. A Japanese bike dealer or shop should have bins of assorted metric screws. I would get a tap and chase the hole though.
The boss will cause problems. You can't fix a loose plate buy pounding on those, because they break off as you discovered. You pound the plate outside the screw slot - held flat on something steel and heavy... not many of us have an anvil but a vise is common. You may be able to get it stable on the small bit of projection remaining, pretty much your only hope? It may be possible to drill 1/6" holes and drive in short split pins if that is no good.

[rickhl]

Just realized that picture is not very accurate. Neither boss has been completely broken off. I'm still able to get it steady, maybe too steady now since it's really hugging it. Don't want to try "unpeening" it since I'm afraid I will end up completely screwing that up.

[jgger]

Maybe some epoxy putty would work to build it back again. Put the plate back on with something like saran wrap behind and around it to act as a separator. Mix up some of that putty stick and press it into place, it goes off in about 5 minutes. Then sand/grind the excess to make it look good. You can have it thicker outside the plate/boss for strength.

It's worth a try.

[DaveBarbier]

I'd leave the bosses as is. They'll still hold the plate. The hardware store will have the metric screws you need but they won't be JIS, big deal. Maybe replace the three with button head Allens. If you get stainless, put a dab of antiseize on the threads.


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[scottly]

Hey guys, new to the forum and to motorcycles in general. I guess this is starting to show since I have successfully broken my crankcase.

I was trying to get my timing adjusted and followed some tips here: http://www.motorcycleproject.com/text/sohcign.html

I "peened" the bosses holding the timing plate since the spark firing mark would not align properly. This lead to me breaking the boss. Do you think this is a big issue or could I live with it like this? 

That guy's recommendation to "peen" those brittle cast bosses is questionable at best. Sorry you had to learn the hard way that just because it's on the 'net, it isn't necessarily true.