Last year when I got my A50 cylinder barrel back from a rebore the cross hatch pattern seemed too smooth, but I used it anyway. The rings did not seat so I am going to have it rehoned locally. What grit honing stones should be used (original BSA rings from Mitch Klempf)?
Dr. Z: The typical range for grey cast iron rings is 150 to 220 grit. A lot of my dealers have settled on 180.
Several years back we brought in Aerco (private labeled by Morris oil) Break-in oil. It was popular with our dealers, but sadly the supply dried up. It was 40 weight and formulated to help prevent bore glazing during break-in. The original Morris break-in oil is now available from:
Great link, Brizzo! I'm only halfway through that one, and I've learned so much. Not to hijack the thread, but how much metal can be taken off with the hone? I have some cylinders which are almost 0.020 over. If I get a piston which only needs a bit larger hole for the correct clearance, how much can I enlarge the bore just by honing with 150 stones?
Thanks for all of the replies. I found an agricultural machine shop here that can do a hone with 180 grit stones. Also the owner of the shop recognized the BSA cylinder barrel; he has worked on Triumphs in the past.
I know this wasn't asked, and excuse me for stating the obvious if you already know, but:
A bucket of hot soapy water (I recommend Simple Green or something of that ilk) is needed to remove honing grit from the cylinder. After scrubbing and drying, smear a little oil in the bores and wipe with a clean white rag. Repeat the process until the rag looks clean after wiping.
Just another little note on Simple Green. For normal washing tasks, it can be diluted like 100 to 1. The first gallon I bought, I wasted a lot because I didn't first read the directions. Properly diluted, a gallon goes a LONG way.
I got the honed cylinder barrel back from the Ag Machine Shop with a nice 150 grit crosshatch pattern, put it back together and went for a short "spirited" ride. It is remarkable how much better the A50 runs with properly seated rings. Thanks for all the help.
It was assembled dry with a drop or two of oil on the piston skirts. After initial start-up it did not idle for more than 10 seconds and I took it out for a ride. I live on the edge of town so it was possible to do a good acceleration in all gears with acceleration and slowing for about three miles. After cool-down the head was re-torqued and the valves checked. Even accelerating in first gear immediately after start-up the engine has a different sound as the throttle is opened.
T100R BSA A10
Re: Cylinder hone grit
#396971 10/01/1110:04 am10/01/1110:04 am
Yep, John changed my whole idea of engine assembly, for the better. I used to flood oil into every nook and cranny before I read his posts for which I am eternally grateful. So it is dry assembly for me, kick t , if it starts then blat around the block a few times then pop the bike on the stand to do the carb adjustments.
The "dry assembly" method pertains ONLY to the cylinder bores. All bearing journals or sliding surfaces like lifters should be liberally treated to a coat of assembly lube. Do NOT dry assemble any plain bearings.
A smattering: '53 Gold Flash '67 Royal Star '71 Rickman Metisse '40 Silver Star '37 Rudge Special sixtyseventy Lightboltrocket road racer...and many more.
I am glad you brought this up. I rarely get time alone away from constant questions and telephones. So I was looking forward to the car ride to the 2011 Vincent Rally in New York. I have had this topic running around in my brain for years and it surfaced some where around Brimfield on the Massachusetts Turnpike.
Most have heard George Bernard Shaw's quote: "England and America are two countries separated by a common language." In my mind this also extends to to the motorcycles we ride. For what seem to me to be obvious reasons, the automotive and motorcycle experience is vastly different in the two cultures. In a period where there was great developments in automotive engineering both countries where going through a depression. This created two completely different automotive cultures.
We had vast amounts of cheap oil and iron ore deposits and Britain had neither. We produced engines that were heavy (cast iron blocks, crankshafts, even pistons), low revving and produced gobs of torque. While our British cousins were using light weight materials (aluminum and Magnesium), low torque and producing its power with gobs of rpm.
Simply stated Horse Power is Torque x RPM. We designed heavy land cruisers and followed the Torque path and the British trimmed all the weight from the designs and went down the road of higher revving engine designs.
So, when you say, "so simply you rode it as normal." many of our US readers feel you are screaming the H-e-l- l out of the engine. Our Chevy Suburban at 1500 rpm in high gear at 65 mph is how we learned life should be. As Norman Hyde is fond of saying, "American's love cuubbicc inches!"
This has been one of my great conundrums trying to explain to someone that it is normal to run these bikes between 3,000 and 5,000 rpm. You are abusing it running it at 1500 rpm in high gear with a 21 or 22 tooth sprocket!!
Thus increasing dynamic cylinder pressure and greatly increasing the chance the engine will detonate, which can lead to pre-ignition. Nearly all engines tolerate some detonation, but in a couple of engine revolutions pre-ignition will hole a piston, or worse.
Forty five years ago I got my first A50 and the BSA dealer gave clear instructions to be easy on the engine for the first 500 miles. I followed these directions, and remembering back that far it seems as if the rings did not set then either when compared with my second A50 today.
After a forty year lay-off, my riding style has changed due to my T100R. During my first ride I was disappointed with its performance, so as a last resort I tried opening the throttle in second. Now I take it up to about 5000 rpm before shifting.
greatly increasing the chance the engine will detonate
Not all detonation is audible to the rider. Put a wind screen on your bike and you will be scared to death. Modern engines use knock sensors which pick up detonation you wouldn't typically hear over the engine noise.
Of course there are other factors that will increase the chances the engine will detonate when you do this especialy the "motor" octane of the gasoline you are using.
But this was aimed at an interested reader, and not specifically to your situation. And anyway, "generally" should imply it can, but not always.