www.boxertrix.com

Since my bike has been serviced at 5000 mile intervals I thought I should do the 24K service (effectively) a little early at 20500-ish, 5500 since its last service. It was feeling somewhat rough.

Starting the night before the main bits with a cold engine I got the valves checked and three reset since I was picky. Rebuilt and ready to run.

So next day, a quick trip out to warm the oils before draining the rear box and seemingly dismantling half a bike to drain the gearbox oil as the 14mm drain plug socket would not fit on an extension or a ratchet due to the exhaust and was disintegrating if I used a spanner.

Oils done and rebuilt I went for the TPS, which seemed ok, but the meter was dithering a bit. Check for a bit of slack in the cables and get a nice balance with the Carbtune, at idle and through up to 4K-ish. The right cylinder was dropping off quite a lot just off-idle and were both spot on in line when I finished.

Nice and warmed up I swapped over the engine oil, which came out so hot as to melt the neck of the old bottle I was using as a drain and poured half a litre over the garage floor!

After a few more checks and cleans I thought since I was on I would investigate the oil mist on the rear box. Delving inside the gaiter gave me a surprise as to how much oil was where it should not be! A good sized pool of the stuff went across pretty much the full width of the arm inside the gaiter. Not good, thought I. Cleaned it all up and hid it out of sight again.

Unable to take the bike out that night it had to wait for test run on Sunday. What a difference! No off-idle stumbles and really pulls from any throttle. Might have been smoother as well but was having too much fun to pay much attention, though nothing intruded.

However:

I no longer have a usable fast-idle lever, which seems to take a little tension out of the throttle cables but not much and does not increase idle speed.

I suspect the gearbox output shaft oil seal has failed/is failing. Is this more likely - certainly with a large quantity of oil - than from the rear box, which doesn't seem to have much in the way of seals from the manual? I take it this is a complete back-end off job? Anyone know the sizes/part codes for non-standard replacements so I can pick one up before stripping it down?

What gives with the fast-idle? It's the first time I've balanced one of these so I may have cocked something up. Have I taken too much slack off the throttle cables in the synch-ing or is something stuck in the splitter box? It sound like things are still moving, just not far enough. I tried tightening up the idle cable but that didn't seem to have much effect.

Ideas wanted for when I get home to try and resolve these issues.

Check the cable is located correctly,they have a habit of slipping out.
gus

One of those oddity's that i've learned with a Twin Max your not balanceing two cylinders!!! your balanceing one ,in all the times i've set mine up i've never touched the left hand side period,just balance the right hand one up to it.

Chris

Yeah, all I did with the left was check the slack on the cable and tweak the brass screw when setting the idle - checked how far out it was by screwing it in then out the same amount and a quarter turn after that when fiddling. Most of the changes were made to the right carb, er throttle body, some on the screw to get an even idle and equal readings on the guage, then on the right hand throttle cable for the off-idle readings.

The cables are not exactly sloppy but certainly aren't piano wire tight. You can see the slack being taken in as you open the throttle, which probably has a couple of mil/degrees before the slack has gone. The cable from the bar is not tight as the revs do not alter as you turn the bars, so I can't see where I have gone wrong.

The only things I can think to do are to slacken everything off completely again, pull the bodywork off and check the cables and box under the tank and then try again from scratch.

But it runs lovely other than that!

My S leaks oil from the bottom of the gaitor @ the rear box and has done so periodically for 40k of its 62k miles. Nothing too serious; just enough to make the rear wheel messy like a chain drive bike. Tends to be worse if I have not ridden the bike for a while e.g. a month. Presumably whatever oil is accumulating finds its way out over a couple of hundred miles, I clean it, and it is not a problem until I again lay the bike up for a while. The non-BMW dealer who services my bike has seen a few 1100 / 1150 variant BMW's do this and has found doing nothing works in most cases e.g. it stops leaking itself. Not often you hear a dealer doing himself out of repair work.

Me-109 wrote:Since my bike has been serviced at 5000 mile intervals I thought I should do the 24K service (effectively) a little early at 20500-ish, 5500 since its last service. It was feeling somewhat rough.

Starting the night before the main bits with a cold engine I got the valves checked and three reset since I was picky. Rebuilt and ready to run.

So next day, a quick trip out to warm the oils before draining the rear box and seemingly dismantling half a bike to drain the gearbox oil as the 14mm drain plug socket would not fit on an extension or a ratchet due to the exhaust and was disintegrating if I used a spanner.

Oils done and rebuilt I went for the TPS, which seemed ok, but the meter was dithering a bit. Check for a bit of slack in the cables and get a nice balance with the Carbtune, at idle and through up to 4K-ish. The right cylinder was dropping off quite a lot just off-idle and were both spot on in line when I finished.

Nice and warmed up I swapped over the engine oil, which came out so hot as to melt the neck of the old bottle I was using as a drain and poured half a litre over the garage floor!

After a few more checks and cleans I thought since I was on I would investigate the oil mist on the rear box. Delving inside the gaiter gave me a surprise as to how much oil was where it should not be! A good sized pool of the stuff went across pretty much the full width of the arm inside the gaiter. Not good, thought I. Cleaned it all up and hid it out of sight again.

Unable to take the bike out that night it had to wait for test run on Sunday. What a difference! No off-idle stumbles and really pulls from any throttle. Might have been smoother as well but was having too much fun to pay much attention, though nothing intruded.

However:

I no longer have a usable fast-idle lever, which seems to take a little tension out of the throttle cables but not much and does not increase idle speed.

I suspect the gearbox output shaft oil seal has failed/is failing. Is this more likely - certainly with a large quantity of oil - than from the rear box, which doesn't seem to have much in the way of seals from the manual? I take it this is a complete back-end off job? Anyone know the sizes/part codes for non-standard replacements so I can pick one up before stripping it down?

What gives with the fast-idle? It's the first time I've balanced one of these so I may have cocked something up. Have I taken too much slack off the throttle cables in the synch-ing or is something stuck in the splitter box? It sound like things are still moving, just not far enough. I tried tightening up the idle cable but that didn't seem to have much effect.

Ideas wanted for when I get home to try and resolve these issues.

If the height of the oil in the bevel box doesn't go down over time then it's your gearbox oil seal.remember a little hot oil goes a long way when it is flung around inside the driveshaft area.
If you do change the seal,don't buy a genuine replacement.Get a double lipped seal from a bearing trader.They are much better and this will probably last the lifetime of the bike.
HTH
Bailey.