I do seem to recall there has been a modification ... Recommend either to get the correct bolts (some digging in old parts manuals required) or to drill & tap the holes in the new cilinder.

rgds
Auke

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Auke
http://aukemarieke.blogspot.com

Hi Auke, thanks for reply, I took the option of making my original bolts shorter. also the 2 long M6 bolts that go from the head cover right through to the barrrel had to be shortened a bit. looks like yamaha made the holes deeper on later 34K00 barrels?

I found this info on later barrels in the archive from a chap called Klaus

as far as i now there is no barrel with code 1VJ.
34K01 barrel was used in 1VJ 1986 together with cylinder head coded 1VJ. the head gasket has 5 bolt holes.
because of the well-known overheat troubles in 1VJ engines, yamaha came up with the 34K02 barrel in 1987 (which made troubles even worser than before), again with 1VJ head.
than, in late 1987, yamaha introduced the 34K03 (also with 1VJ head). this one was o.k. because of longer threads for head bolts.
the xt600 2KF model which came on market in 1987 was also equipped with 34Kxx / 1VJ.
then in 1988 both tenere 3AJ and 2KF where equipped with the advanced 3AJ00 barrel and the 2KF head. from that day on untill nowadays every xt600 is equipped with this barrel and head.
it must be stated that every barrel fits every bottom end, you only have to take care about the barrel / head combination. so, 2KF head will fit only on 3AJ00 barrel while 1VJ or 34L head both will fit on 34Kxx.
the difference between 1VJ and 34L head is the smaller valve diameter of the latter.
the difference between 1VJ and 2KF head is the 6 bolt fixing of the latter plus the bigger distance between the two downwards facing fixing M8 bolts (in cylinder head).

cheers

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http://picasaweb.google.co.uk/andypackham
http://www.youtube.com/user/yahyajammeh

Is it also likely that a previous owner could have made the modification?

I have three 1VJ engines - all 34k00 y1 barrels - two of them have 30mm holes on cam side and 40mm holes on other side. All bolts are 105mm

The other engine -- holes are all 5mm deeper - bolts longer.

PS::: Is that the STANDARD original piston???

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no its a new replacement oem spec .75 oversize





the old one


the worn bore and piston was letting loads of oil past

cheers

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http://picasaweb.google.co.uk/andypackham
http://www.youtube.com/user/yahyajammeh

Oh HA HA!

I recognise that old piston!! (from your other post!)

How has it all gone, by the way??

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all back together and no smoke now

not sure what sort of running in is recomended on a rebore & new piston?

next on the list of things to do is

sort out carbs - i've got another pair to try out and fiddle with.

sort out excessive vibes (really bad over 50mph) - not sure where to start with this, can anyone can give me a list of things to check engine wise?

and when its all running right I'll look at cosmetic stuff

__________________
http://picasaweb.google.co.uk/andypackham
http://www.youtube.com/user/yahyajammeh

For the excessive vibes you have to go cosmetic! lol

Replace the XT's stock front fender with one of those from the YZ or WR!

makes a humongous difference on the vibes at higher speed!


Vando