KR-1S.co.uk Forum

bought these kr1s barrels a while ago. they have been replated,and have,nt
been used. so like new.
my question is, what spec are they.
they have had 1/2 mm skimmed off the top[so am guessing would run with
the base gaskets doubled up.
all the ports have been worked. in fact, they have had a lot done to them.

I do have a pair of new Yamaha tz 59w pistons/rings to fit in them.

Hi Martin,
From the looks of it the port windows havent been altered just tidied up after plating.
No need to run 2 base gaskets with the head skimmed (just a way of raisng the compression,i would do a dry build though and check the squish isnt LESS than 0.7mm.
You may have to remove material from the powervalves as with the top skimmed they will protrude above and get pinched when torqued up (the head),you can use a lathe or a file to thin down the round parts that are upper most on the valves themselves.
Looks like the standard fair in mods,shorten the rear lugs to improve intake charge,looks like the transfer divider has been knife edged (not a good idea as the stock rounded type is well designed.
The exhaust port may have been raised but without measuring its impossible to tell.
HTH
Dave