Cylinder condition help

[jumjum01]

I bought this cylinder block and pistons along with other spare parts. Will a re-hone "fix" the mark in the top of the cylinder barrel. The mark in the barrel fells smooth when you run a finger nail over it. I dont know what caused this, mabye some of you guys can tell for experience?

 

[GIXERHP]

Needs to be checked, Run a approved hone over it and measure it

 

[jumjum01]

Needs to be checked, Run a approved hone over it and measure it

Just measured the cylinder bores, they are 81.035mm, so they are no good, except for big bore core exchange

 

[Berlin Germany]

Just measured the cylinder bores, they are 81.035mm, so they are no good, except for big bore core exchange

in prinzipal i would contradict

the standard piston size from factory is, following the manuals from gen1 & 2, at both 81 mm,
what means the real bore size is around 81.03 - 81.04 mm
so that your measure is still in specs.

but the dark dot on the pic makes me suspicious - in my view a bad sign - and causes by that the cyl. should be bigbored to 1st oversize (or replaced by "new").

but that 1st over would be very expensive - i guess ~ 1500 € at minimum
cyl. drilling + honing 1 over ~ 250-400€
nikasil re-coating ~ 400-600€
piston set 1st over ~ 600€
ring set 1st over ~ 300€

a good, preowned, block incl. pistons (with no bad marks, etc.) should cost for gen1 around 350-500 bucks
plus a set of new standard piston rings ~ 280€
then youre at ~ 600-800€

allways plus gaskets etc.

a usual block / piston set should last, thank to the nikasil coating, for way over 200 000 km
provided that the engine has always been warmed up well, has always experienced good oil change intervals and has not been constantly driven at very high to maximum rpms .
the rings eventually should be replaced after 20 years and more of being pressed in the cyl.
they may lost some springforce
what can cause a lost of compression and a increased oil consumption .

 

[pcs]

probably needs to be looked at by a machinist. from the pic it looks like the nikasil plating could be damaged. if the coating is chipped or burned through, it would need to be recoated. some people use that time to bore to the next size piston. you don’t have to go to a bigger piston unless that is what you want. you can stay with stock sized pistons even if the coating is chipped. you would just need a replate. in my opinion that piston got to hot, lack of oiling? expanded too much in the bore and rubbed the cylinder. good luck.

 

[Berlin Germany]

@jumjum01

as we here like to say sometimes :
even if you paint s hit three (or more) times with yellow color it won´t convert to butter.

so, give the old block to the scrap box and
get a good, preowned, 30-40000km block .. (see above)

a new (re-)coating with nikasil is, as i understand, at the same prize level like a rpladement with a good, preowned, block

regarding the age of the bike (gen1 ?), I would definitely recommend the new piston rings.