Gs850 boring

[Guest]

How far can you bore out a gs 850?
I was looking at 1mm

[Burque73]

I saw the title and thought, boy the 850 gets no love. Boring bike huh? LOL

Are the walls gouged up badly and that's why you're asking about the bore? Seeking more power maybe? I have thought about dropping in an 1100 engine for more power but not really serious about it right now, just considering.

Curious to see what replies you get here.

[Atro211]

Thanks, took jugs off and a little gouging going on not to bad, had sit for about 3 years and was smoking a little,rode around several miles and did not reseat rings, so since I was rhere, thought for more power!!! Ha you know

[Big T]

Ride it 300 miles and see what happens
Valve stem seals are the most likely culprit for the smoking

[Nessism]

Most GS engines have liners thick enough for a 3mm over bore. I'm not sure about the 850 though. But even if the liners could take it that doesn't mean anyone actually makes 3mm oversize pistons.

A quick search on ebay shows that cruzin image makes 1mm oversize pistons. I think those would be your best bet.

[Steve]

1mm should be real easy. 2mm? Will probably be OK. Not so sure about 3mm.

Trivia point: a 1mm overbore will be the same as the stock bore on a 1000.

Still won't have the stroke of the 1000, so displacement will only be about 868cc.

.

[Atro211]

Thanks for the information, I just found out cost,holy crap Batman,75 a hole, I guess I'll try to save it by honing as much out, and get oversized rings and file down to fit, the cylinder is not to bad really just wanted to start fresh any suggestions?

[Nessism]

I guess I'll try to save it by honing as much out, and get oversized rings and file down to fit,

I would not do this. Standard rings are to be used when the bores are standard size.

[Atro211]

I agree with big t, it probably was valve stem seals they were hard as rocks when I took them off

[GS1150Pilot]

Thanks for the information, I just found out cost,holy crap Batman,75 a hole, I guess I'll try to save it by honing as much out, and get oversized rings and file down to fit, the cylinder is not to bad really just wanted to start fresh any suggestions?

These motors are so good that it's worth doing it right. You get what you pay for with machine work.

[Nessism]

APE charges $50/hole for boring. No way I'd pay $75/hole when you can get a world class company like APE to do it for less.