At it again.

Fra Cristoforo Posts : 767 Join date : 2016-04-14

Customer is now putting 1200 cyl on his 1100G, what an 1136 or some such thing. He may get 10hp, maybe.

Don Abbondio Posts : 6080 Join date : 2014-03-13 Age : 69

a 1200 ish 2V engine can be made into a well sorted steed, especially with assistance form Mr Beetle

Fra Cristoforo Posts : 767 Join date : 2016-04-14

Just wondering if anyone else here has done the big bore conversion. I would imagine cut cyl's and trim the piston tops.

Don Abbondio Posts : 6080 Join date : 2014-03-13 Age : 69

Just replace the 1100 crank with a 1200 one, barrels, cylinders to match - I assume the stroke is different so go with the 1200 crank. If the throttle bodies and heads are the same, they should be good to go. Mapping will need to be changed.

Guest

It would be faster with Matris'd ends on it.

Tiradritto Posts : 309 Join date : 2013-12-17

I have test reports for the 1100 GRiSO and 1200 Norge both by the same magazine (Motorcycle consumer news). The GRiSO makes 74.19bhp/57.85ft lbs, the Norge makes 71.2bhp/59.2 ft lbs.

I have owned a 1200 Breva (Norge without fairing) and a 1200 Sport both 2 valvers and couldn't tell the difference between the 1200 and and my present 1100 engine.

Fra Cristoforo Posts : 767 Join date : 2016-04-14

This particular G11 has been breathed on very heavily, pretty modified. Kinda like a grenade if you do too much wfo. Owner loves it to death. Now he wants a bit more. I'll bet the pistons will have to loose some weight.

GRiSO Capo Posts : 10413 Join date : 2013-05-29 Age : 67

I was trying to remember if the 1100’s and 1200 2V’s use the same stroke? They don’t, the 1200 has a 3mm longer stroke. Now unless I’m mistaken they both use the same rods which means the deck height of the 1200 pistons would need to be 1.5 mm lower. Sticking the 1200 barrels and pistons onto an 1100 would result in low compression ratio and lousy squish, you certainly wouldn’t gain anything I wouldn’t think. You might be able to turn 1.5mm off the bottom of the fins but I don’t know if the spigot would then foul the crank or if the rods would foul the cutaways in the spigots? Compression would still be down though.

I think if he wants to do it properly he’ll need an 81mm crank as well.

Pete

Fra Cristoforo Posts : 477 Join date : 2014-01-07

lot of work/money for little gain. More power> get other cam.

Guest

Buy a Suzuki? scratch

GRiSO Capo Posts : 1657 Join date : 2014-09-22

buy a 1200 motor

Fra Cristoforo Posts : 767 Join date : 2016-04-14

It already has a cam in it, we did that 1st time around. I think he likes riding his Triumph but likes wrenching on the G.