conversion of GL1100A to GL1200A

[Dale Landan]

is it possible to bore an 1100 out to 1200 standard, and are the rods the same length. what is the bore diameter of a GL1200, my GL1100 is 74.9xx and is very rough near the top of the cylinder on #3 and and # 4 looks like heavy pitting. I would consitter boring the standard GL1100a out to either a first or a second over size, but seem to have a great deal of trouble finding the pistons and rings for same. My 82 Aspencade quit at 33,745 miles. My Honda dealer wants 75.00 for a single set of rings for the standard. Which I feel is awhole lot of hard cash for a retired aircrafter. dplandan@gmail.com

[newday777]

You can get a whole motor to put in for $100-$400.

What happened to your motor at that so low of miles???

[Dale Landan]

I bought two gl1100 for 800.00 dollars one a standard was in running condition, but had not been registered since 2008. The other was an 82 Aspencade that was missing a big bunch of parts and had not been registered since 2002. It was missing carbs. seat, air inflation system and lines,control head and false tank, and the engine and water pump were "frozen". After pulling the heads found rings rusted to cylinder walls on each piston with a lot of manual labor and some judicious work on the cylinders and a lot of force on the alt. shaft, I managed to break them free then found the cylinder pitting which I estimate to be approx. .005 to .008 deep. I thought the rings might be frozen on the pistons and I an currently almost convinced they are. I have not torn down this engine since this state California requires engine number as well as frame for reg. I bought a used engine and before I could get it installed it to became frozen, this one I have torn down and the rings were frozen in the piston lands I broke two getting them un stuck and this engines walls were pitted also. This engine was out of a 1980 engine as I discovered after pulling off the front cover and found the neutral switch to be wholly different. so that pretty much covers the story. dplandan@gmail.com would like to hear more.

[Old Fogey]

As you have already found, oversize pistons for the 1100 are virtually non-existent. Rebuilding the four cylinder engines is expensive, even if you can find the parts! Trust me, I know.
The 1100 block will bore to the 1200 75mm and oversize pistons are available from CMSnl, the 1200 piston pins are different size to the 1100 and although the conrod bearings are the same I don't know the length of the rods so can't say if they will interchange. you would also need to check the pin/piston crown height as well.
As has been mentioned, your best bet is to change engines, even put a 1200 in there!