XJ750-P Cylinder Head Questions

Hi,
I have the head off my XJ750-P (NZ Police model XJ-750) fixing a plug thread and doing valves etc and noticed "XJ2" stamped into fin on underside





This mean anything to anyone?

Also what is the little tit in the combustion chamber near the spark plug for?





The only thing I could think of was to shape the flame front from the spark plug but that's just a guess.

Regards
Richard

 

YOU HAVE THE SECRET MODEL... THE XJ2, THOUGHT UNTIL NOW TO HAVE BEEN ONLY A BLUEPRINT... THE SOLUTION TO ALL OF OUR PROBLEMS...

...WHERE DID YOU GET IT?!?!?!!



Wish I knew something to help you. Sure rick or chacal or fitz will know something...

 

Hello Richard'.. i can't tell you what th numbers mean either but th 'little tit' are in my spare head from a 1981 750 seca, what year is your bike.
Th head has 2L359 stamped in where yours has th xj2 and below that faintly cast in either 116 or 776 on th other side (left upside down) 5G200 cast in and further left Y-4 cast in.
You could try sending member cds 1984 a pm, heres some of his stuff
http://xjbikes.com/Forums/viewtopic/t=29398.html

 

Hi,
fintip I got it off a brit guy I think his name was Bond, James Bond

But seriously I wish it was something special but its just an old high mileage ex Police bike. Its still fun to ride though, a bit of a blast from the past compared to a modern bike.

Bushy its an 83 NZ Police model 24L code. The other side on it has 5G201 and Y-5 cast in.

Richard

 

mines got 4T2 stamped there.

 

Wouldn't hurt to round some of those sharp edges in the chamber while the head is off.

 

Hi yes its getting the usual basic head work while its off, smooth the steps where seats are cut, blend the rough casting bits and pieces, smooth the sharp edges, back cut valves, 3 angle valve cut etc. Some of the OEM machine work on the seats is a bit rough with pretty big steps left and there are a few lumps in the intake tract where the casting core was not quite right.

Interesting having a look at the YICS jet with the position and angle its at it looks like it would not only improve turbulence(something the ancient Hemi type combustion chamber design would really like) but also help stop the short side of the intake track flow separating and stalling by filling in the lower pressure area there.