Big Bore??

[chrisso]

Howdy all, whats the biggest I can go to on the XS1100 without cyl liners??How much power increase with standard carbs??
Cheers

[Crazcnuk]

1196 Wiseco, I think.

I have a 1208cc RC Engineering kit, but they are no longer available.

[chrisso]

Further to talk on big bore kits ive been getting opinions on SmoothBore carbs---heres what ive been told on another Forum;
Any thoughts peoples???Zed reference was about my Z1 1000 i put a 1075 kit in,--went great;;; they dont seem to think its so good on the XS????????????


Quote---------Yep Frog.
The Zed had a really good profile from the start Chrisso and I have sneaking suspsicions they were sleeved down for longevity reasons, not that they needed it anyway.
The Yammy cam was known as a soft profile, or better stated, a short duration and easy ramp angle. Stock was fine but blokes who bored them often complained about a midrange flat spot, that didn't go away until about 7500rpm when the needles where totally raised.
The fix was a more aggressive ramp angle and longer duration. This also lifted top end, but at the expense of clutch packs and sometimes the alternator rotors would lose a magnet and bingo, dead electrics followed very soon by loud graunching sounds. Of course this was more from caning the poor things than reliability issues.

The whole idea of smooth bores and polished inlets got shelved when it was realised that fuel would collect on any sharp turn in the inlet tract, and this actually reduced preformance. A little bit of rough was creating turbulence and assisting flame fronts etc.
In a drag engine, the inlet tract is as straight as possible and the charge is rich and travelling really quick, so they are still used. Velocity stacks can be tuned for certain RPM settings too. For a ride every day bike they are trick to look at but do bugger ull under 9/10s I reckon.
Cheers, Pax

[TopCatGr58]

Hey Chrisso,

Do you want a rideable bike or a racebike?? The XS11 is what it is. Yes, you can pour "some" $$ into it and get "some" increase in power and performance, but takes a lot of $$ to get modern sportbike speeds and such, not really worth it, better spent on a Modern bike!

Due to your isolated location, and the climate....heat....you might think about going with the smaller of the big bores, unless you get an oil cooler...the big bores really thin the cylinders and do create a bit more heat.

Smooth bore carbs are more for the racetrack....WOT type running, not for in town rideability. Many folks have recently put on MODERN regular carbs and have gotten good performance, reliability, ease in finding parts due to being newer, easier tuning, etc.!!

My stock 81SH had plenty of power when it was new, I only bored it due to neglect, internal rusting, etc.! I went with the smaller bore so IN CASE I ever needed to bore it again, I had a little more room to put the last bigger size in, not realizing that I could probably get a spare set of used cylinders and just rebore to the small big bore size I already have and put in new rings.

Happy shopping.

[chrisso]

thanks... im just throwing ideas around at this stage-the bike still goes well, its done 210,000 km. is on its 1st Oversize. doesnt use any oil & has an oilcooler.

[79XS11F]

My 1179 kit with 4 into 1 pipe and enlarged exhaust ports works real nice. YES the mid range is a little flat but hang on when she's in the sweet zone again ... If you want to throw a little more cash at it and can find the parts ... put in heavy duty valve springs. The XS11 is know for floating her valves even at moderate RPMs.
Rob