The bottom end is common so the studs will be in the same place. You rebore the 3tj barrels to the 600 pistons ... I thought you got 560cc from it ?
It would be simpler to just do an engine swap and use a 600 lump

In another country that might be an option. I think I best just tidy up the engine as it is.

I see

LiteTekBlair wrote:Hi EC and All,
So can someone tell me if you can bolt a YZF600 Thundercat top end onto the 3TJ bottom?
I have seen various posts about this sort of thing e.g. it yields 490cc but no one posts rod lengths, whether the stud pattern is the same etc.
cheers
Blair

Yes, it can be done, and goes quite well. (I'm using that setup in my 3TJ road racer.) Steve @ Speedwerks in Deleware, US is the gent who built my motor along with a couple other examples beating up on bigger machines in the US. I'd give him a ring if you want details on the build. It's not a pure bolt up, some machining is required, but you end up with a beautiful motor when done.

I contacted Speedwerks but it is all top secret. Haha
If I discover some details I will post them up.
cheers
Blair

So Boris whats been happening with this Engine?

It's been sitting on a bench ... I'm scarred the bench might float away if I take it off.
Tbh ... I'm trying to get some enthusiasm together but since I got hit off I've lost my motivation. .. although that was 2 years ago

Ressurecting an old thread I know but need some help.
I have built a 660cc engine and have it running in my track bike.It's been out twice now and both times I have lost the last 5mm of the piston skirts.They are breaking up where they get very thin at the bottom. My idea is just to remove this part of the skirt and re balance the pistons.
Has anyone else had this problem? I'm guessing it's because the pistons run further down the bore with the longer throw.
There is absolutely no contact at BDC.
Mark

I haven't heard about it .... sounds a bit worrying

It is,You wouldn't know from doing an oil and filter change as the bits are in the Strainer mesh,Doesn't stop it running well so maybe no one has noticed.I always drop the sump and strainer after the first run of a newly built engine that's how I found it.