Hi all !!

I have just a little question : does anybody try to go from 74mm bore to 79mm bore with gse cylinders

(I thought it was possible, but now I have measured,  and  )

well why not get rid of the sleeves altogether and nikasil the block...or better still...get a whole new block made from billet and nikasil the cylinder...cant be too much $$$
Cool.
Srinath.

In fact, I first thought it was possible to enlarge the lining, from 74mm to 79mm...

On the top, I have about 90mm (when I saw that, wahoo!! 79mm is too small ) , but on the bottom, the part that goes in the motor, I only have 83mm, on the largest part
I think that's really small to bore at 79mm, isn't it ?

79 mm is a GSXR 1100 bore isn't it...Cant you pull the sleeves out and bore the block and put in the GSXR's sleeve. That would be ~615cc... people have run up to 680cc (Cedric Smith back in 95-96) and then he was breaking cranks with regularity...so he droppped to 580 and didn't break that whole year. Anyway somehting can be done...ask the experts...
Cool.
Srinath.

And while your at it, cut the cases in half and add two extra cylinders!  

seriously, past 76mm (512cc or so), you have to punch out and resleve the cylinders. At past I think 78mm (540-550cc) you have to cut the cases to allow room for the larger liners. 79.5 is the absolute max size before you cut into the oil passages that feed the head.

Hey I think my machinist can make me a cylinder block out of solid aluminum. So I can use no sleeve and nikasil the thing. Can you say heat transfer... and tight clearance... aluminum pistons in an aluminum block... Should I use 6061... or 2024.. or what...
Cool.
Srinath.

In fact, it's for my gsx400
So I'm interested by the xjr1300 pistons (79mm bore, as the gsxr, but with a 18mm axe, as the gse and the gsx).

The motor, except pistons (67mm on the gsx) the head (4 valves per cylinder), and the cylinders (liners smaller than the gse) is strictly the same as the gse one ...

My idea was to put gse cylinders on my gsx (I have a complete gse motor, with a dead head), re-bore the cylinders at 79mm, without changing the liners ... I've read somewhere that if you leave 3mm (so 6mm at all), that's possible...
When a friend measured his liners, he told me that It was 87mm. So 79mm was good for me ...
But when I measured mines, I found 90mm at the top (ok, that's good), and only 83mm at the bottom (hum, that's quite bad, it only leaves 2mm )

that's the whole story

So in fact, the only possibility is to change the liners ?
(or I re-bore at 76mm, that's good for xjr1200 pistons )

So you want to take a (too us) a GS400 and put a bored out GS500E cylinder in?

You also have to worry about stroke, compression ratio, and the piston face to cylinder head/combustion chamber squish band profile.

Yes, but a gsx400 bloc, with the 4 valves per cylinders
the gse cylinders are just the same, but with bigger liners, and these liners can be changed...
(I already have both, a 1980 gsx400, and a gse motor, with a dead head, and also a working stock gse )

for the stoke, that's the same (same bloc), but that's true the compression ratio is 10.5:1 for the gsx, and will be increased while re-boring (about 12.5:1 in my estimations).
For the pistons, the xjr's ones are quite good, light, and for 4 valves per cylinders (but they probably must be adjusted a little ..)

I had a stock cylinder block that was bored to 79 mm. The sleeves were very thin, but it did work. I ran it a bit lean for awhile, and with the thin sleeves, it scuffed a piston. I think maybe the thin sleeves go out of round easily when heated too much. It made good power though.

I now have a resleeved cylinder with an 80 mm bore. It has aluminum sleeves with Nikasil coating. If I can ever get a bottom end to hold together again, it feels like it makes great power. The cases have to be machined out. I'm not sure what oil passages are supposed to be cut, but I have an 80 mm bore that works.

It isn't the big bore that is causing my bottom end problems. The first one was just too much racing on the countershaft bearings, which don't like all the high rpm. The second was not being able to get a complete set of new main bearings in time for a race, and I don't think it liked the mixture of new and old shells.

the 79mm pistons is a 555 kit, i have one piston left from prev owners built engine.

ok, so it can be done, but the main problem is overheat of the cylinders, that can destroy liners and pistons...

What do you think of putting an oil cooler, to prevent from overheating??

(the new gs500f has one, so it probably can be adapted on our old blocs ??)

last question, does the liners must be "nikasil" after such an operation ??
(2.5 mm removed from the liners...)

Quote from: KevinC
I now have a resleeved cylinder with an 80 mm bore. It has aluminum sleeves with Nikasil coating. If I can ever get a bottom end to hold together again, it feels like it makes great power. The cases have to be machined out. I'm not sure what oil passages are supposed to be cut, but I have an 80 mm bore that works.

Kevin, do you know who did the work or still have the specs?  I am hunting around for someone to build something similar for the new bike.

Thanks,
James

James,

I haven't a clue who did the work. I got the engine in pieces from Pam G., who got it from John M.

If you use the same shop, don't let them sandblast the head gasket surface!

Quote from: KevinCJames,

I haven't a clue who did the work. I got the engine in pieces from Pam G., who got it from John M.

If you use the same shop, don't let them sandblast the head gasket surface!

isnt james g married to pam g?

Nope Greg G is married to Pam G...
Cool.
Srinath.