1982 1100G rebuild

[Jrgunn5150]

I ran a compression check on my 1100G today that I'm building as a winter project, and the results weren't great. I had numbers from 120 down to 80, number 4 came up with oil in the cylinder, number 3 didn't. Bike has unknown miles, the speedometer was ripped off it when I bought it lol, but I'm clearly looking at a rebuild here.

So some numbers I found on the web are that i have a 72mm bore, and a 66mm stroke, assuming everything is stock, with a compression ratio of 8.3:1. What I can't find, is anything else I'd need to calculate compression ratio, like gasket thickness, chamber size, piston dish CC, etc.

I'm not going to spend cubic dollars on this, but this kit, https://www.cruzinimage.net/2017/08...-1100cc-bigbore-piston-kits-with-head-gasket/ , seems like a great value. It's listed as compatable up to 81, and I have an 82..

So what's the difference? Also, what search terms do I need to use to find pistons for my 1100G as opposed to an 1100E, which seems to be all that comes up when I look.

Really, I don't have alot of money in this thing right now, so if it's going to be alot, I can punt it and start over with another/better bike. I'm really just trying to explore options here. And for my budget for this thing, 600 pistons, aren't an option.

 

[Nessism]

How long since the engine last ran? Have the valves been adjusted? Was the engine burning oil? Was the compression test performed with the engine hot and the throttle held open?

Unless there is rust in the bores the cylinders and pistons are most likely okay for reuse. Use a bottle brush hone and new rings, assuming everything measures out okay that is. Don't assume, measure.

 

[Charlie G]

When I got my 1100g the previous owner said the compression in #3 was below 50psi. I checked and adjusted the valves and "Amazingly" I was at plus 130 on all cylinders. #3 was three times the max clearence. Check the valves.

 

[Jrgunn5150]

How long since the engine last ran? Have the valves been adjusted? Was the engine burning oil? Was the compression test performed with the engine hot and the throttle held open?

Unless there is rust in the bores the cylinders and pistons are most likely okay for reuse. Use a bottle brush hone and new rings, assuming everything measures out okay that is. Don't assume, measure.

It ran when I bought it, so it ran, like two weeks ago. I kept the running limited because I new literally nothing about it, except it ran.

The compression test was performed cold, with no carbs on, so the throttles were open.

I have not checked the valves, but I do intend to do so during my teardown, just to have a baseline if nothing else.

There should be no rust issues, since I rode it onto and off of the truck.

If the pistons are good, and the bores are in spec, I do intend to just re-ring it and put new gaskets on it and send it. If not, then I would like to have other options on the table.

When I got my 1100g the previous owner said the compression in #3 was below 50psi. I checked and adjusted the valves and "Amazingly" I was at plus 130 on all cylinders. #3 was three times the max clearence. Check the valves.

Well that gives me hope lol. I had some hope that it might just be the valves until I saw the sub-90 numbers on 3 and 4. At least I know I don't have a hole in a piston or something lol.