Running in....Please pass

[Bodysurfer]

Well, I opted for castrol GP mineral and have just finished 200 miles zipping around the Brecon Beacons and Herefordshire. Kept the bike under 6000rpm almost all the time didn't labour the motor and tried to let it rev freely. Chose one less gear than I would normally use in built up areas.
Lost one bolt on the exhaust heatshield that I must have forgotten to tighten up properly . Oil level on return is exactly as it was on the way out though I guess its much too early to tell yet. It will be a week or so before I can get out again and a lot longer until I'm sure things are fixed. When I get a result I'll post it.

[thetimkirby]

I stand corrected, AlanH. But I'd like to get to the bottom of this ring/bore bit. As I understand it, the rings are hard and brittle, and are precision ground to size. The bore is of softer steel, and is only machined and cross hatched. I thought the rings wore the bore to fit them, not the other way round. I can't see how a ring that's too hard for a file to scratch can be worn by the ridges on a softer metal. After all, when the engine is clapped out, most of the cylinder wear is on the bores, not the rings.

[Kjell Lindberg]

Informative article about cylinder bores and the art of cross honing the bores:

Classic Techniques: Cylinder Bore Honing - RealClassic.co.uk

Something to consider when changing piston rings, and the bores are worn.

[underbeing]

Any updates on the oil consumption now? Also, just how bad was it before?
I can't decide whether to do the same or just keep topping the oil up. I'm concerned that i may spend a load, only to find that other things might have been knackered by whatever knackered the bores and valves. I must say it still goes REALLY well despite the heavy oil use and back firing.

[Bodysurfer]

Any updates on the oil consumption now? Also, just how bad was it before?
I can't decide whether to do the same or just keep topping the oil up. I'm concerned that i may spend a load, only to find that other things might have been knackered by whatever knackered the bores and valves. I must say it still goes REALLY well despite the heavy oil use and back firing.

No update on oil consumption at the moment due to lots of work and ****e weather. Oil consumption was about 500ml per 1000 miles which I think is the upper limit of Honda's spec. (I'm sure someone will correct me if I'm wrong)
My thoughts on doing the work were that I intend to keep the bike long term, it is a low mileage bike so I felt confident in the diagnosis of the problem.......we'll see and finally, I've used it to Morocco and intend to do so again. It was nice to pull it all apart and find out whats what and how the thing goes together. In a way, I enjoyed the experience. One day that knowledge may be valuable.
Other side of the coin is £300 buys a lot of oil.
Why not sit tight at the moment and see if mine settles down.
What's the mileage on yours?

[underbeing]

mine uses 'max' to 'min' amount of oil every three fill ups of fuel. so thats about 1000km ish.
Mileage says 27k km. Its an import with no history, so its probably done 127k kms.

[Bodysurfer]

mine uses 'max' to 'min' amount of oil every three fill ups of fuel. so thats about 1000km ish.
Mileage says 27k km. Its an import with no history, so its probably done 127k kms.

That sounds like a lot. I suppose it all depends on the mileage. If its 27k it would probably be the same problem as mine had. If its 127k it be all sorts of other issues. If this is the case I think I would keep adding oil for the moment and consider a full rebuild as and when.
Then again there's always this option.......

HONDA AFRICA TWIN BARRELS&PISTONS on eBay (end time 29-Nov-09 19:02:15 GMT)

or better these........

HONDA AFRICA TWIN 2mm OVERSIZE BARRELS&PISTONS on eBay (end time 29-Nov-09 19:02:29 GMT)

[Bodysurfer]

An update on oil consumption/running in for anyone interested.
After the work detailed above was finished I started the run in process. The first 200 miles or so were with the revs kept under 6000 most of the time but with the engine spinning freely. One less gear than normal in built up areas and as much engine braking as possible. No detectable oil use found.
The next 600 were normal quick riding but making sure there was no letting the engine labour. After this there was a little use, I guess about 200ml.
Oil and filter were changed and next came a 3500 mile round trip to Morocco.
During this the bike had long periods of high speed running fully laden with all the camping gear down and back through Spain. In Morocco it was mixed road and off road riding. Results were that there is now minimal use of oil, it didn’t need topping up all trip and I would estimate use for the entire trip at about 250ml.
I’m going to keep an eye on it for the next 4k “normal riding” and see what happens. All in all I’m happy with the result.

[btbloke]

What's The Best Way To Break-In A New Engine ??
The Short Answer: Run it Hard !

Why ??

Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.

How Do Rings Seal Against Tremendous Combustion Pressure ??

From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into

the cylinder surface, to seal the combustion pressure as well as possible.

The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!

If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
which is why more engines don't have this problem !!

An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!

Absolute tosh! goes against the whole principle of engine manufacture and all the theories of metallurgy and metalloid principles as well as a few mineralogy rules.
If you want a 40-50k engine with crossed fingers try this method,if you want a reliable 100+K engine use a tried an tested running in method.

[btbloke]

mine uses 'max' to 'min' amount of oil every three fill ups of fuel. so thats about 1000km ish.
Mileage says 27k km. Its an import with no history, so its probably done 127k kms.

probably run in the quick thrash way