First time engine rebuild

[The Buddha]

2400 miles - I didn't remmeber that. Well you check ring end gap in the chamber they will be coming out of. Suzuki has sucky tolerances, it may be too big to be fitted back in by any sane mechanic.
That blowby causing oil black = its loose fitting, if it indeed is blow by that caused it.
Cool.
Buddha.

[The_Paragon]

All petty arguement aside...

If all the dang motor needs is a base gasket.. IROAN (Inspect and Replace Only As Necessary.)

No sense in replacing a whole engine just because of a base gasket failure.

Here is what would be my plan of attack: replace the base & head gasket. If she's an oil burner, throw some new rings at it, and give the bores a quick hone.
Give the head a quick look over, check valve clearance and adjust if needed.
DONE.

[The Buddha]

It has 2400 miles, but that dont mean squat with suzuki's tolerances being treated as a mere suggestion.
I'd be inclined to measure it, and maybe fit new rings, but its possible that the thing was loose from the factory. The thing may not take a stock ring with in specs even if it had 0 miles. It should be measured, and that should determine if you need the 1/2 mm over set. You're not supposed to fit 1/2 mm over ring in a stock piston set, only 1/4 mm max, which is not available. What a load of BS. My old school mechanic suggested to me that 1/2 mm hand fitted ring is useable in case of bigger bores (what is big - no clue) but a GS is 74mm, probably big enough IMHO, the contect he was using it was in the 102mm in my MZ.
Anyway, measure the bore, it may be fubar already, cos it wasn't that much better when new.

Cool.
Buddha.

[sledge]

Geeeez, talk about making a simple job difficult. You say `blown` Have you actually seen the gasket? Are you sure its not just weeping? The base gasket sees no compression, therefore there is no pressure behind it to `blow` it.

GS5 needs the headbolts  re-tourqing at the shakedown, its specified in the service schedule FFS. If it doesn't get done the base gasket weeps..THEY ARE FAMOUS FOR IT!!

If you took it to a pro and were told....blah blah blah..new......2400miles??.....blah blah blah......
new base gasket.....blah blah blah......rebore......new rings...blah blah blah then started a thread about it in here there would be 100 posts all saying the same thing........HE IS TALKING CRAP AND TRYING TO RIP YOU OFF!!

If some people in here actually tried to make a living servicing and repairing bikes they would never see a customer return and starve to death in a frickin month 

Check the torque on the headbolts....or do it the hard way and risk some even bigger problems.........your call.

[The_Paragon]

^^^ The man makes a good point..

Re torque the head bolts and see what happens.. If it stops the leak: Battle Won!

Just how much oil does it leak? lots of 4 strokes weep a little oil around the base gasket. My wheeler weeps alot of oil around the base gasket, I just keep tabs on the oil level and drive it.. It doesnt really bother me much at all. Every not and then I take some degreaser after it.

[The Buddha]

Sledge - I bought a 1983 Tempter (even looks like a GS motor) that had 5k miles in 2010. It had a base gasket leak. Its sorta prone to that. I torqued the head bolts etc etc. I could have torqued the daylights out of it, but I was going to check if it had a defect.
Anyway, its possible that the thing could just be torqued. So its worth a shot.
But I also have not torqued it on many GS'es and never had a leak. I've had ultra low mile bikes in my past.
But it may do the trick.
Cool.
buddha.