81 R100RT Break In

[Pierce]

Well, my bike, "The Great White", because it's white, has been in pieces for a few years and I am now very close to starting her back up after a total rebuild, crank and all. My question is what weight of oil should I use for the break in period? And what method of running. I'm sorry if this is reopening a can of worms. I have done this before, but only for the top end. The last time I did this I used 30 weight non detergent oil. I was told by the dealership mechanic to fire her up get on it and run for about an hour keeping the rpm's around 4k. I can't wait to get this bike on the road again! :D I like my 03RT, but there's something about an Air Head isn't there. Pierce

[Boxerkuh]

I would use 30 weight oil and ride the bike for about 500 miles, then drop all the oil out. I would suggest that you change the rpm's on a frequent basis, I would not go over 3000 rpm for the first 500 miles though. Good back roads are best for this, for frequent upshifting, downshifting, going through all the gears. This process will not only make sure that you get the motor, tranny and rear end set up, but also all the cables. So, after 500 miles you will also want to check the cables and make minor adjustments. Then after another 2000 miles I would do the same again. Good luck and have fun!

[ssls6]

Don't forget to retorque the heads after a few hundred miles.

[James.A]

That pretty much covers it.

[Motorman]

As an aircraft mechanic who has rebuilt ac engines I can attest that the best way to get the rings to seat is to use non detergent oil.

I'd make sure the engine had oil all through it. Pull the plugs and crank it with the starter for a bit to get the oils circulating. If the oil light goes out so much the better, if not crank it for about 30 seconds then again for 30 secs. after letting the starter cool. Re install the plugs and start it. Run it briefly maybe a block or 2 then after checking for leaks get on it and run for at least an hour or better and at decent RPM's. Don't thrash it but you want to get some power out of it. Let the RPM's fluctuate as well. After about 500 miles or so change the oil and filter and put in your choice of detergent multiweight. Go back to a normal oil change routine after that. Don't run it too hot or hard or you risk glazing the cylinders. If you do that you'll never get the rings to seal and it will burn oil badly.

If you have an oil temp guage, a drop in temperature should signal that the rings have seated and friction has reduced.

[rinty]

My specialist also recommended 4000 rpm max when I broke in my RS.

Rinty

[pmdave]

I've rebuilt a few R motors. On assembly, I use lithium-based assembly lube on rotating parts, to help prevent scoring on startup. The idea of cranking the engine to fill the oil galleries is clever.

I don't believe there is much difference in lubrication between detergent and non-detergent; the difference is mostly in keeping any bad particles in suspension. So, to convince me of the need for non-detergent oil for break-in, I'd need some technical justification. I would avoid synthetic oils for break-in, since synthetics are reputed to have better lubrication--which would detract from seating the rings.

Personally, I use 20W50 for break-in, but change it after a few hundred miles to remove any particles left over from the overhaul. (metal filings, gasket goo, etc.)

I believe in running the engine at a variety of loads and RPMs, so that the parts (rings, cam followers, etc.) get run in over a broad range of limits. I'm not a believer in revving a new or rebuilt BMW engine to the limit until it has been "exercised". In my book, the ideal way to break in a rebuilt airhead motor would be to ride a twisty backroad that requires lots of changes in speed. (acceleration, deceleration, cruising at various different RPM ranges)

It's important to not stress the motor before it is up to operating temperature, to avoid blowing gaskets, bending valves, etc.

Yes, do retorque the heads and other fasteners within a hundred miles or so. That not only helps cinch things together, but allows some expansion and contraction to settle in the gaskets. You may also discover oil leaks that need fixing, valves that need readjustment, or fasteners that weren't tightened enough on assembly.

It's always amazing when (after you've checked the oil for the tenth time, filled the tank, flipped on the switches) you hit the starter and it settles into a nice cadence with no strange noises.

pmdave

[b_h_dowell]

Take a look at the web sites below. I broke in my 79 R100RT using the hard breakin method recomended by both sites and was very happy with the results. I am a helicopter pilot with some experience years ago on piston powered rotary and fixed wing aircraft and I am pretty sure that aircraft engines are not broken in with the long drawn-out manufacturer recomended slow break-in. Also I am sure that racing motorcycles use a much quicker break-in. http://www.mototuneusa.com/break_in_secrets.htm http://www.one-ring.net/vfrfaq/general.html#breakin

[Pierce]

Thanks for the help guys! I got the jugs assembled and installed on the bike today, but somehow, I came up short one nut for one of the rockers. I hate it when that happens! I swear I put EVERYTHING in plastic baggys and labled them when I took it apart 2 years ago! There is a local beemer shop I'm going to hit up for a spare tommorrow. For now, I just used one of the head to cylinder nuts just to hold everything in place with some pressure until I get the nut and properly torque it down. In fact I was so excited to get to work on the bike today, I forgot our monthly meeting this morning. DOH! Pierce

[carockwell]

It has got to be impossible to ride an airhead under varying loads for 500 miles without exceeding 3000 rpm. The worst thing you can do to a new motor is overheat it. The motor does not want to get super hot, so no sustained full throttle high rpm operation, or sustained full throttle at any rpm. It helps to vary the speed and load. Winding roads or city traffic work well . Really congested city traffic is bad because you sit still so long that the engine gets really hot.

[Pierce]

Well, on the 3rd push of the starter button the "Great White" came back to life after a nearly 3 year sleep! I can't believe I got all the wireing right the first time either. There's 10 miles on the odo now. I'm waiting for a DRY day to get on it and ride a bit! :dance