rebuilding r60/5 engine: displacement++

[Orpheus]

A long while back I started considering this rebuild, but I forgot pretty much all of the advice everyone told me (except some stuff from wirewrkr... hmm...).

Anyway, I bought a ratty R60/5 as a project bike. At first I was thinking I would go for a cafe bike, but my heart was always set on a sidecar. When I found a nice CJ sidecar, I picked it up. It has done an excellent job collecting dust.

But now it's time to tear down the R60/5 and make a respectable hack-hauler out of it. Now is not the time to suggest buying a "more appropriate" airhead that won't "take thousands of dollars and likely several years" to rebuild. Pfft.

My goals are:

* To learn how to tear down and rebuild an airhead engine.
* To wind up with an engine that can haul this solid sidecar with me + passenger at modest back highway speeds.

I had a list of things to buy. That list is gone now, but I bought one thing on it: a 1975 R75 camshaft. Great, I know. Here are the other things I remember folks suggesting:

* R75 cylinders (/5 or /6, I can't remember which, with the intention of boring out to R80 spec).
* R75 heads (again, don't remember the model/year range)
* R80 pistons
* ???
* Different carbs... ?
* ??...zzz

Sound about right?

[davef]

You've got the right idea, but your list needs to be a bit longer:

The cam

Cylinders, pistons, heads (go for something from the /6 range, which began in 1974. I've seen a bunch of these parts for sale at ibmwr.org)

CV carbs off a 750 /6, or better yet, some modern mikunis like these http://www.rockypointcycle.com/Merch...egory_Code=B12.

Needle bearing rocker arms (again, I've seen a full set for sale recently on ibmwr)

However, to take full advantage of all the new power, you'll likely want a five speed tranny from the /6 series 750's, and a final drive unit with the appropriate ratio to plant that power to the ground.

I've been collecting parts for my R60/5 project, which started because my motor ingested metal needle bearings from one of my rocker arms. I was lucky enough to find a freshly rebuilt R90S motor bored out to 1080CC. Now, I'm searching for the carbs, tranny and final drive. The thing will be a beast in sheep's clothing when I'm done.

I'll eventually rebuild my R60/5 motor and use it as the basis for a stripped down, off-road bike. Here's what I'm starting with for the /5 monster bike:



Good luck with the project, sidecars are a load of fun. I just finished my r50/2 sidecar project:

[PaulRS]

Those cast cylinders can go up to 900cc.
Fit R80 heads with 40/42 mm valves.
32 mm CV carbs, jetted to R90/6 spec. (or as above Mikuni)
320 degree cam for low rev grunt.
5-speed box with 10/32 FD for 18" wheel, or 11/33 for the 15" conversion.

More, and more and.............

Paul.

[Orpheus]

Is there enough material in R60/6 cylinders to bore out to R80 spec or do I need R75 cylinders?

[wirewrkr]

Originally Posted by Orpheus

Is there enough material in R60/6 cylinders to bore out to R80 spec or do I need R75 cylinders?

you will need trashed 1970-75 750 cylinders.
PM me I probably have a trashed set cheap.
here's a picture of a split open r60 cylinder
it's in the 1970-1975 range, and as you can see the
thickness of the cast sleeve is the same all the way through.
Unlike some later cylinders that were hourglass shaped.
the bore for R80 is 85 mm. the wall thickness is between 5 an 5.5mm.
do der math.
Robert

[davef]

I saw a bunch of 750 and up cylinders and heads available here:

http://www.ibmwr.org/market/adlist.php?cat=aps

I've got no affiliation with any of them. However, I also noticed a bunch of five speed trannys and some decent final drives on the list as well. Seems like you should be able to find everything you need here.

Good luck. Remember to start a thread with lots of pics when the project gets started.

[PaulRS]

Ok, done some research.

Pictured here are one R60/5 cylinder and one R75/5 bored to 90 mm, 900 cc.



Both cylinders are from the same <'75 era, with the 16 mm tubes.
Quite a difference here, the R60 has a liner of 91 mm dia and the R75 97 mm, also the R75 is slightly bigger overal.

If you want to take the R60 out to R80 specs, it leaves you with a liner of 3 mm thick, will that last? I think yes.

You want bigger, use the R75

Paul.

[wirewrkr]

Originally Posted by PaulRS

Ok, done some research.

Pictured here are one R60/5 cylinder and one R75/5 bored to 90 mm, 900 cc.
Both cylinders are from the same <'75 era, with the 16 mm tubes.
Quite a difference here, the R60 has a liner of 91 mm dia and the R75 97 mm, also the R75 is slightly bigger overal.

If you want to take the R60 out to R80 specs, it leaves you with a liner of 3 mm thick, will that last? I think yes.

You want bigger, use the R75

Paul.

Dude! what are you smoking?
that "liner" as you call it, is half aluminum!
Did you not even look at the picture that I posted earlier?
The actual cast iron liner is only 85mm o.d.
the bore for an R80 is roughly 85mm.

[PaulRS]

Read your post, looked again at your pic, went back in the shed and came to some conclusions.

Your'e right, must stop smoking.

And use the stupid reading glasses when doing research.

Paul.

[wirewrkr]

Great reason to stop smoking, worked for me!
RV

[Orpheus]

Thanks for the jugs, wirewrkr!



So if I use R75 cylinders bored out to 85mm and R80 pistons, should I be using R75 heads or R80 heads?