Will xjr1300 cylinders fit fj1200 3cv 1989

[gpspl]

Hi,
I have one spare engine for my fj1200 and I would like to make full rebuild of it. I've been wondering about "upgrading" to xjr1300 cylinders and pistons. Will they fit will stock fj head work with it?

[Pat Conlon]

Yes, the FJ head will fit on the XJR block. You will have to trim the cooling fins on the XJR block to fit in the FJ's perimeter frame.

[melloncollie]

My understanding was you only needed to trim the head, not the block. 

RPM and Andrews Motorsports both offer a drop in kit for this, otherwise machining the lower cases is required.  Note they both mention custom sleeves:
http://www.rpmracingca.com/proddetail.asp?prod=1250Bloc
https://andrewsmotorsports.mybigcommerce.com/cylinder-kit-yamaha-xjr1300-block-1250cc-oem-piston-kit-5ea113111000-1250/

And here's a thread where one of the kits is used:
https://fjowners.com/index.php?topic=14834.0

[fj1289]

Another option - Robert at RPM has a 1250 kit based on FJ cylinders and XJR pistons.  Pretty sure they are in stock and ready to go

[RPM - Robert]

My understanding was you only needed to trim the head, not the block. 

RPM and Andrews Motorsports both offer a drop in kit for this, otherwise machining the lower cases is required.  Note they both mention custom sleeves:
http://www.rpmracingca.com/proddetail.asp?prod=1250Bloc
https://andrewsmotorsports.mybigcommerce.com/cylinder-kit-yamaha-xjr1300-block-1250cc-oem-piston-kit-5ea113111000-1250/

And here's a thread where one of the kits is used:
https://fjowners.com/index.php?topic=14834.0

Melloncollie is correct only the head needs to be clearanced. The 1200/1250/1300 heads are all the same minus the egr ports on the 1250 and laters, if you even have that new of a 1250.

Rebuild your 1200 head with new springs and such. And use a bigger bore up to 1380cc then you don't have to do any extra clearance work.

[melloncollie]

gpspl: is the spare engine a 1200 or 1300?  I read the post as the spare engine is another FJ1200 and the goal is to put xjr1300 cylinders and pistons on the spare 1200.

[giantkiller]

Hank Scott Real Race Cars. Must have trimmed mine. I didn't have any clearance problems with my 1350. Wasn't listed in estimate.

[RPM - Robert]

The case would also have to be clearanced to fit the larger diameter sleeves in to the case.

Unless you use the 1250/1300 case.

[aviationfred]

the case would also have to be clearanced to fit the larger diameter sleeves in to the case.

If you use the RPM 1250cc cylinder kit or the Andrew's Motorsports 1250cc cylinder kit. No modifications are necessary.  Both kits are True plug and play.

As for the cylinder head..... an OEM FJ1200 head will work just fine on a 1250cc.

I put about 15,000 miles on the big bore cylinder kit with a 100% stock head. I upped the game slightly and added over size valves to the head a few years ago and maybe put another 5000 miles on the engine and high flow head.


Fred