rebore? or not

[Guest]

Hi fellas
can you tell me at what stage do you re-bore, my Gs1000gt 1980 has been re-bore 0.5mm over size before , and the bore size now is 76.62mm would you say I need to re-bore again, I was thinking of a big bore kit if I had to re-bore but there's a couple on the market and I wouldn't know which would be a better quality, and what jets if any would I have to fit to my cv carbs if I use big bore kit, and were would i get them

mark

[blowerbike]

buy a stock cylinder and have your piston's fitted to it.
cheaper in the long run.

[Nessism]

Hi fellas
can you tell me at what stage do you re-bore, my Gs1000gt 1980 has been re-bore 0.5mm over size before , and the bore size now is 76.62mm would you say I need to re-bore again, I was thinking of a big bore kit if I had to re-bore but there's a couple on the market and I wouldn't know which would be a better quality, and what jets if any would I have to fit to my cv carbs if I use big bore kit, and were would i get them

mark

Wow mark, hard to read...

Stock bore is 70mm. More confusion.

[trippivot]

when to rebore

measure your pistons
and measure your cylinders on the "X" 12/6 oclock and "Y" 9 and 3 oclock axis, top middle and bottom . 6 measurements per cylinder.

#1. when piston to cylinder clearance gets about 0.007" (0.003 is fresh)
#2 when cylinder gets a barrel shape where it is loose in the middle and tight at the top/bottom
#3 if there is a taper pattern in the cylinder

if everything is .004 to .006 consider a simple ball hone and rings only.

[Nessism]

The piston to cylinder clearance service limit with stock Suzuki pistons is .0047", with .0020-.0024" being the OE clearance. Aftermarket forged pistons need more clearance however.

[bsa44161]

rebore

sorry guys
too much red wine last night , i re measured today and all four bores are 70.41 to 70.46. as i said the pistons have.05 on the top so assuming its been rebored .05mm over size, so with the measurement im getting would you say it needs a rebore or just a hone,
Or install a big bore kit are they worth it? and whats the better kit on offer, and yes the same question again is, what jet size would i need to go too.
hope this makes sense
mark

[Nessism]

sorry guys
too much red wine last night , i re measured today and all four bores are 70.41 to 70.46. as i said the pistons have.05 on the top so assuming its been rebored .05mm over size, so with the measurement im getting would you say it needs a rebore or just a hone,
Or install a big bore kit are they worth it? and whats the better kit on offer, and yes the same question again is, what jet size would i need to go too.
hope this makes sense
mark

Suzuki discontinued the .5mm over bore rings. I suggest you measure ring end gap and go from there. Unless the engine has a lot of miles on the rings they may be serviceable as is. A big bore kit will add some torque, but will cost you a good deal of cash.

As for the carbs, rejetting depends on the intake and exhaust system. With pods you will need drastic rejetting, the easiest way to go is with a Dynojet kit. If you keep the stock airbox then you may get away with shimming the stock needles and upping the mains. Good luck with all that. Keeping the bike stock will save you money and rejetting headaches.

[tkent02]

With a bigger bore you would probaby need smaller mains if anything.
Another option would be a GS1100G or GK top end.

[Montanaman]

Is your engine burning oil or down on power ?

I just had a big bore kit put into my big Kawi, and when the day comes that my '83 starts feeling tired I'll probably do the same -

Pro's - Big bore kit will get you more displacement, more compression, lots of power -

Con's - lots of power means more heat, more pressure on bottom end/clutch, need for a good starter motor, and a trip to the premium pump forever thereafter -

[Montanaman]

Plus another con: I went out on the road today with the son-in-law on my '83 GS1100ED, and I took the '82 GPz1100, and in 3rd gear nailed it, and at about 8000 rpm the clutch started slipping - thought it was a fluke - repeated it in 4th gear, and guess what, at 8,000 rpm the Hp is overwhelming the clutch/springs.

~sigh~ I'm just trying to preserve some pieces of motorcycling history, not stimulate the economy

[tkent02]

Those springs have been compressed for thirty years, they are shorter now and provide less pressure.
The good news is they are available and cost very little.

[bsa44161]

rebore

no the bike isnt burning oil according to the previous owner, i have never seen it running as i bought it as a basket case, and im rebuilding it, that's why Im asking if those bore measurements are OK and i"ll just hone it and put in a new set of rings, I found a aftermarket set of .05mm rings for sale, i would rather keep it standard if possible
mark