Overbore for ST1100?

[Ozzy]

My ST1100 has 200,000 miles on it and while running well is down on power. I am considering replacing the rings this winter. I feel that an overbore is the only proper way to address this. How much of an overbore can the ST1100 safely and reliably handle?
Thanks.

[Horst]

You'd figure Paul would have an answer ! ...

Good to know ... when my 2002 gets up there, maybe I can still get them ... good luck and let us know if you do this ... so what does that make it ? ... a full 1,100cc ? ... maybe 1,157cc ?

[Putt]

before you consider boring, get a good internal mike and check the
bores... If they are still in spec, (and not tapered) you just might
have to hone the bores to scuff them up a bit and just install
new piston rings... The new bores are HARD and wear very little.
Might save a bunch of bucks..


Putt...

[CarSalesman]

Have you done a compression test? If not, why do you suspect rings or bore? You could just as easily have a worn cam, or some other problem. I know 200k is a lot of miles, but I wouldn't automatically condemn the cylinders.

If you really do confirm the cylinders are worn, there are plenty of used ST1100 engines available at a modest cost. That would be better and more cost effective than rebuilding the old one. Lots of wrecked bikes with low miles out there.

[Ozzy]

Have you done a compression test? If not, why do you suspect rings or bore? You could just as easily have a worn cam, or some other problem. I know 200k is a lot of miles, but I wouldn't automatically condemn the cylinders.

If you really do confirm the cylinders are worn, there are plenty of used ST1100 engines available at a modest cost. That would be better and more cost effective than rebuilding the old one. Lots of wrecked bikes with low miles out there.
No I have not done a dry/wet compression check yet but before the actual teardown of the bike the cams and compression will be checked . The bike is in cold winter storage ( its in my snowbird parents garage) until early spring. That will be when I get to it.
I did think of the later model ST1100 engine swap, but have never seen an engine for a modest cost that shipping costs didnt kill.

On my semi retired income modest is modest, $500 is a lot of money, half a months worth at times.

[Mike]

200 K, might consider a carb overhaul as well and this may restore the power you are missing assuming your compression test are okay. The needle jets and needles are probably worn and wallowed out allowing too much fuel flow off throttle and into WOT. Main jet may well be worn as well. Linkage that penetrates the throttle body may be wallowed allowing air to flow into the carb causing a lean mix.

[jackpine savage]

You'd figure Paul would have an answer ! ...

Good to know ... when my 2002 gets up there, maybe I can still get them ... good luck and let us know if you do this ... so what does that make it ? ... a full 1,100cc ? ... maybe 1,157cc ?

The ST1100's bore and stroke are 73 x 64.8 mm. So adding a quarter and half mm to the bore gives 1094 and 1099 cc respectively. I always thought the B & S were more square than that.

David