Another Vintage Project, 1968 DT1

[SachsGS]

The piston looks like it has little blow by.Why not measure the top end, it may still be fine.I recently found an old KX and the top end is brand new.

[citabjockey]

This top end is the least of my worries on this bike. As I can go up to 6th over there are plenty of options. The fork tubes, transmission, the seat, getting things rechromed, repainted, etc are going to be much larger road blocks.

If the piston and bore does measure up I may just slap it back in there. As Sachs says, it does look to be in pretty nice shape. As I can go up to 6th over there are plenty of options. Of course putting the existing piston back into a bike I hope to have "new" in most respects doesn't really feel "right"...

[SachsGS]

The cylinder liner gets awfully thin on those 5th and 6th overbores. On some of the old 360/400 Yamahas I've seen the hone break thru. to the alu. cylinder on the 6th bore.

[cnrcpla]

Sounds like maybe you shouldn't go for a 6th bore even if you had to.

[citabjockey]

Right now the liner measures about 4.5  mm thick. Must have started out as 5 mm (its a 1mm overbore now). So that removed 0.5mm off of a 5mm liner. If I go to 6th over that will remove another 0.125 from it. Hard to say if that is going to make it break. A good question for my engine builder expert. Thanks for the heads up on this guys.