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73 R60/5 F'ed up cylinders

r60celo5

r60celo5

New member
thought i would share some photos from my rebuilt.

through the spark plug hole i could see that the cylinders tops were oily and had a lot of build up. i was hoping it would need new rings and a reseal.

started with the left cylinder and found a puddle of oil at the bottom of the cylinder.

IMG_20210212_125013.jpg

the ring end gaps were all over the place. up to 1.53 mm on the oil ring. i am assuming the rings were filed down but butchered in the process.
Polish_20210212_170925564.jpg

left cylinder taper and out of round were out of spec. 0.001" and .0005" respectively.

started reading what my options were trying to keep this rebuilt in a budget and decided to just get new rings and ride it till it it smoked oil.

this morning took apart the right cylinder. there is pitting at bottom next to the ridge. i am not bothering with any more measurements - it needs a boring and new cylinders. with the dial bore i get about 0.003" deep pitting.

IMG_20210217_104144.jpg

IMG_20210217_104202.jpg

what can cause such damage? stuck engine maybe?

what would you do?

bore + new pistons?

used cylinders and pistons?

upgrade to R75?
 
Depends

Your course of action will depend on how bad things are with what you have.

Find a good, preferably BMW airhead oriented machine shop and have them measure things out. Then when you have the numbers as to what you have on hand, you might get by with rebore and new pistons, or you may have to sleeve and new pistons. It all depends on the bore numbers and what the numbers BMW lists for rebore specifications.

If you go to Snow bum's pages, he may have data on what the specifications are for boring one over, two over or what the limit of reboring may be for your cylinders. Someone else may write a link to the data as well. I think the Clymer manuals have it as well.

I can't comment on going to a 750 set up as I don't know if there is just a piston and jug change or if you would need connecting rods as well. You would I think have to change your heads to 750 heads or have the 60 heads modified.

To be honest, I would contact Ted Porter or one of the other BMW shops who do this kind of work. They would be a better source of information than me. St.
 
Pitting And Flaking

Looking at all the pitting and flaking in your cylinders, it musta spent many years, even decades sitting. Sitting, without even occasional turnover, is probably the biggest enemy of our Airheads. Agree, now would be a good time to explore options in upgrading to larger displacement.
 
i have looked up the manual and the rebore options are +0.5mm and +1.0mm.

i was gonna go with the new rings only but with the pitting on the right cylinder makes me wonder if its even an option.

i am looking into local machine shops if they can do the boring. anyone has an idea what it will cost to have these bored? does the R60/5 cylinder need the specialized pressure plates machine

should i get the pistons first then take it all to a shop to be bored and new piston fitted?

i am located in Westchester NY. any recommendation for a good machine shop in NYC area is appreciated.
 
I would want someone familiar with BMW engines to do the work. I'm sure a very reputable engine shop could do it, but I'd put my money on BMW. MAX BMW is up the road in Brunswick NY. Tom Cutter is is Yardley, PA, going the other direction about the same distance. Tom would be the ultimate go-to guy in the NY area.

I think there is an issue with the R60 series bikes and the cam profile being used. I believe I've read that a proper upgrade for an R60/5 bike to an R75/5 would (or should) also include a cam change. Snowbum might have something to say about it.
 
i also found that each cylinder had 2 (two) base gaskets. i read up on it and it seems to lower compression slightly and avoid pinging.
say i get the new oversize pistons and bores, should i plan on using 2 base gaskets on each side?

i can live with the 600 CC engine (it matches the title), unless its cheaper to upgrade to 750 with good used parts.
 
Yes, a base gasket lowers the compression. That was a quick fix to the 600cc issues. If you get your cylinders back to usable status, my guess is that you should consider the additional gasket. The issue is that the stock advance curve comes on too quickly for the R60/5. One fix is to change out the advance unit for one sold by Boyer. It has programmable advance curves and you might find one that works well with just one gasket. But you would need to make that decision up front when everything is going back together...you don't want to remove it all later on to remove a gasket.
 
Pinging R60/5

r60celo5 said:
i also found that each cylinder had 2 (two) base gaskets. i read up on it and it seems to lower compression slightly and avoid pinging.
say i get the new oversize pistons and bores, should i plan on using 2 base gaskets on each side?

i can live with the 600 CC engine (it matches the title), unless its cheaper to upgrade to 750 with good used parts.
Click to expand...
I recall the early 1980s, when dual plugging was in vogue, the R60/5 was reputed to the worst at pinging so most in need of dual plugging. Double base gaskets were likely an attempt to lower CR and combat ping. The BMW factory did something similar with the R100 motors in 1980, when they lowered CR to 8:1. In 1981 they introduced nikasil jugs, and went back to 9.5 CR. Long story short, if you stay with 600cc, might wanna buy an extra pair of jug gaskets, though it's like putting a bandaid on a sucking chest wound, IMHO.
 
looks like

Looks like you are near MAX or Cutter's shops, I would not go cheap with a local machine shop but would have the work done by BMW airhead people.

They will be able to tell you what options you have regarding the boring and such.

They will also advise you in regard to upgrading size of engine and the problems involved along with the best approach to any other issues in regard to pinging and such.

Good luck. St.
 
r60celo5 said:
i have looked up the manual and the rebore options are +0.5mm and +1.0mm.

i was gonna go with the new rings only but with the pitting on the right cylinder makes me wonder if its even an option.

i am looking into local machine shops if they can do the boring. anyone has an idea what it will cost to have these bored? does the R60/5 cylinder need the specialized pressure plates machine

should i get the pistons first then take it all to a shop to be bored and new piston fitted?

i am located in Westchester NY. any recommendation for a good machine shop in NYC area is appreciated.
Click to expand...

No machine shop that is professional would bore cylinders without having the new pistons on hand for the final hone!
 
r60celo5 said:
i also found that each cylinder had 2 (two) base gaskets. i read up on it and it seems to lower compression slightly and avoid pinging.
say i get the new oversize pistons and bores, should i plan on using 2 base gaskets on each side?

i can live with the 600 CC engine (it matches the title), unless its cheaper to upgrade to 750 with good used parts.
Click to expand...

Even though the block spigot specs increased to 99 MM from your 97 MM in '76, I believe that you could bore your cylinders from 73.5MM to 84.8MM to accept pistons from an R80/7. Even with the milder cam, it would improve your HP and torque a significant amount. I believe it would necessitate sourcing a pair of R75 heads though and maybe carbs too. I have read of inmates here who have successfully punched their 600's out to 750 CCs using the stock R60 cam. My '78 R80/7 needed new rings and head work and I thought of upgrading it to 900 CCs with jugs, pistons, and heads from my very low mileage '76 R90/6 (retired) parts bike. Alas, just like yours, I found pitting in one cylinder so I opted to just bore out my R80 cylinders. A local reputable motorcycle/snowmobile machine shop charged just $100 CAD per jug including media blasting and hone. I welcome any comments yay or nay. PM sent

Russ '76 R90/6 (lawn sculpture) '78 R80/7 '78 R100RS
 
Last edited:
thank you all for the input.

seems like Nikasil plating is the most cost effective way to go. my pistons look good so at least i might be able to save some money there. yes it will take new set of rings compatible with the Nikasil coating.

anyone has had their steel sleeve cylinders plated with nikasil? any feedback?

thank you.
 
I had my R25/2 cylinder plated with a carbide treatment from Bore-Tech...Vech at Bench Mark Works was responsible for getting that done. I'll let you know 20 years from now how it worked! :wave
 
20774 said:
I had my R25/2 cylinder plated with a carbide treatment from Bore-Tech...Vech at Bench Mark Works was responsible for getting that done. I'll let you know 20 years from now how it worked! :wave
Click to expand...

20 years?

if nikasil is good for 20 years i got the answer to my question.
 
Well, my R25/2 might not be the "north star". I put only 300-500 miles a year on it. So 20 years might be 10000 miles? Hardly a challenge for the coating.

My recollection was that with the '81-on models which come equipped with a Nikasil coating, the thought was that one would run 100K miles, rering, and go another 100K miles. Snowbum has a lot on Nikasil here:

https://bmwmotorcycletech.info/cylinders.htm
 
Nikasil

20774 said:
Well, my R25/2 might not be the "north star". I put only 300-500 miles a year on it. So 20 years might be 10000 miles? Hardly a challenge for the coating.

My recollection was that with the '81-on models which come equipped with a Nikasil coating, the thought was that one would run 100K miles, rering, and go another 100K miles. Snowbum has a lot on Nikasil here:

https://bmwmotorcycletech.info/cylinders.htm
Click to expand...
Over the decades, I have heard nothing but good about the 81 and later nikasil cylinders. Can't say same a similar approach by Moto Guzzi, with their chrome/nickel lined cylinders, which tended to flake. Never heard of that with the nikasils, but I've been mostly out of the Airhead loop on for the last 15 years or so, so maybe problems have cropped up later?
 
can anyone recommend a reliable source of used parts? (other then Ebay)

looking to find a set of R60/5 cylinders within spec.

feel free to send me a message if you have a set for sale.

thank you.
 
There's a used parts section in the link in my signature line.

Names that come to my mind are Airhead Salvage, Repsycle, Bob's BMW, maybe Beemerboneyard. Years ago I bought something from Joshua Buck in California. And Stoner's Beemer Stash might be someone to check with.
 
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