Crusin Image 1370cc Big Bore Kit

Waiting on valve springs and valve seals.

Looking good Frank!

I wonder what paint did you use. Looks shiny.

The valves in the back, are they new or are you going to re-use them? And did you machine the seats or just lapped the valves?

Stan

I cleaned all the valves and lapped them. I had planned on putting in new valves but these, the seats and the guides are all good.

The exhaust side had heavy carbon build up. Worst I’ve seen since a motor I was into in 1981. Had to chuck the valves up in the lathe. Used paint remover and pressure washer to clean the ports.

Have valve seals and springs on their way.

I ground down the more visible casting marks on head & cylinder, then used VHT engine paint and VHT engine gloss clear.

BTW, did not want to clutter up the piston ring topic - it seems to have a life of its own. But the pistons that were in this motor had 0.8mm compression rings. It’s a 1980, but it has definitely been worked on before. It’s a 60,000 mile bike, but no way this thing was refreshed much more than 10,000 miles ago.

It’s a 60,000 mile bike, but no way this thing was refreshed much more than 10,000 miles ago.

From what I've seen, three KZ1300 heads but of course it's universal, some with a radical lesser mileage ( 8 like the one I am riding now, and others less than 20), all exhaust seats had some scarring. I lapped valves on the third one for now, this will be used, and while all in general looks good and I'd swear they will seal, there are still dark marks on the contact surfaces which are pitting. Did you just let it go on that principle?

The exhaust valves where a PITA to remove the black areas from the sealing surfaces, but they did all 6 clean up with one small piece of scotch bright (1/3 of a pad). So the "pitting" could not have been more than a thou as you really can't remove any significant amount of metal with a scotch bright pad.

The valve seats show no pitting on the sealing surface after I lapped them. And I did not go at it hard. I have one of those lapping tools that goes in a drill (it oscillates). I hit it for a second, pull it back, turn the drill 1/4 turn and hit it again for a second, repeat. Probably did 10 seconds with medium compound and 10 with fine.

If you look at the KZ1300 book it has a drawing of what to look for in the contact patch. Mine looks just like the "good" view.

I just got lucky that it was done properly last time around.

I got this as a basket case because the previous owner had no compression on #3 (like 20psi). Rest of the cylinders were good. Oil pressure was good. Owner and his mechanic buddy disassembled to put new rings in it, but then could not figure out how to put it back together.

My best guess is the valves had not been shimmed in a long time (or not correctly). I have seen no issue with the pistons/cylinders/head. I should find out for sure when my springs/seals show up, as I've not done anything that should appreciably change the valve clearances.

The previous owner had bought the bike used. This KZ1300 was his FIRST MOTORCYCLE. So I'll bet he did not/does not understand the need for adjusting the valves.

I can't imagine this as a first bike! I went the normal 250, 380, 600, 1000, etc route. Cannot imagine learning to ride on a 700lb bike. Has been dropped a couple of times, but just scuffs than can be fixed. One of the side covers is buggered, but he included a brand new one to replace it!