Mailman’s XS2 a full on restoration

[Mailman]

I just had to add one more thing here. When I first took off this morning, the first stop I rolled up to the idle suddenly dropped and it felt like it wanted to die. I took off and everything was fine. The next stop sign I rolled up to the idle dropped again and this time it actually did die. That’s never happened before! It started right back up , I blipped the throttle and rode away. I kept running things through my mind, what could be causing this?

Then it hit me. The last time I had it out, I rode it until it got good and hot , and two things happened. The idle crept up so I backed the idle screws off a little to bring it back down. Also when my bike gets hot , my clutch free play loosens up and I get too much free play at the clutch lever and neutral starts to get hard to find. So using my little thumb wheel, I had removed all slack from my clutch cable. And I left those two items that way when I parked my bike.

So....today when I started out , my idle was too low and my clutch was dragging with the lever pulled all the way in.
When I would come to a stop, the slow idle couldn’t overcome the drag of the clutch and the idle would drop too low and the engine would die.

 

[MaxPete]

First of - well done on that danged leak Bob - you’re a skilled, methodical and determined guy and it pays off in two beautiful motorcycles.

On the idle thingy....yeah, some days the idle is up and some days it’s down. The key point is that our XS650s have a totally open loop fuelling system and a fairly primitive one at that. That means that the engine operating settings (air / fuel mixture, ignition timing, idle throttle setting...), remain the same regardless of the actual operating conditions - hot / cold, humid / dry, high ambient barometric pressure or low., high rpm or low, high power demand or low....

As a consequence, fiddling with the idle on an XS650, occasionally, is perfectly normal and definitely not an indication that anything is wrong with the engine, the ignition system or the carbs. I think I’ve got my 1976 XS650C (the redoubtable Lucille ) dialled in very nicely, BUT - on especially hot or cold days, I still have to tweak the idle screw and blip the throttle.

On a modern motor vehicle, all of the above engine functions, plus things like fuel injection timing and even the number of “squirts” of fuel per engine cycle (and even per cylinder), are monitored and varied hundreds or even thousands of times each second to ensure that the engine is running just right at all times.

As a result, we get instant starts, steady idle, good power from sea level to mountain tops, hot or cold, rain or shine, PLUS, tremendously long life for spark plugs, exhaust systems and nearly all other engine components.

Back in the 19650-60s, the life of a car was generally agreed to be around 100,000 miles or 10 years but nowadays, the average age of vehicles on North American roads is more than 11 years (!) and having a car go 300-400,000 km (which is more than 250,000 miles) is not unusual. While at least some of that durability is due to much better metallurgy and factory paint jobs - a good part of it is due to modern highly accurate digital engine controls.

The next time you see a car from the 1960-70s - follow it for half a mile and you will see (and mostly - smell) the difference.

Pete

 

[geedubya]

I haven’t even fired the bike up since installing the new seal. It’s been 90 degrees at sunrise here now. I’ve had a hard time getting excited about riding.

Man up B-O-B

Get out there and get your knees in the breeze and when you come home have several refreshing beverages.

 

[geedubya]

First of - well done on that danged leak Bob - you’re a skilled, methodical and determined guy and it pays off in two beautiful motorcycles.

On the idle thingy....yeah, some days the idle is up and some days it’s down. The key point is that our XS650s have a totally open loop fuelling system and a fairly primitive one at that. That means that the engine operating settings (air / fuel mixture, ignition timing, idle throttle setting...), remain the same regardless of the actual operating conditions - hot / cold, humid / dry, high ambient barometric pressure or low., high rpm or low, high power demand or low....

As a consequence, fiddling with the idle on an XS650, occasionally, is perfectly normal and definitely not an indication that anything is wrong with the engine, the ignition system or the carbs. I think I’ve got my 1976 XS650C (the redoubtable Lucille ) dialled in very nicely, BUT - on especially hot or cold days, I still have to tweak the idle screw and blip the throttle.

On a modern motor vehicle, all of the above engine functions, plus things like fuel injection timing and even the number of “squirts”, are monitored and varied hundreds or even thousands of times each second to ensure that the engine is running just right at all times. As a result, we get instant starts, steady idle, good power from sea level to mountain tops, hot or cold, rain or shine, PLUS, tremendously long life for spark plugs and nearly all other engine components.

Pete

G'day Pete,
I have found here in the tropics that the ambient temperature has little or no effect on my idle speed.......bearing in mind that I am 12feet above sea level.

GeeDub

 

[5twins]

One comment on your "when hot" adjustments - you made the clutch adjustment tighter then left it there. When the bike cooled and things contracted, that clutch adjustment would get even tighter. On your next ride, starting out, the clutch shouldn't have been dragging with that even tighter adjustment. If anything, it might have slipped some.

 

[Mailman]

One comment on your "when hot" adjustments - you made the clutch adjustment tighter then left it there. When the bike cooled and things contracted, that clutch adjustment would get even tighter. On your next ride, starting out, the clutch shouldn't have been dragging with that even tighter adjustment. If anything, it might have slipped some.

Yeah, you know , I didn’t think that through. You’re right. So my problem must’ve just been an idle set too low.

 

[Mailman]

First of - well done on that danged leak Bob - you’re a skilled, methodical and determined guy and it pays off in two beautiful motorcycles.

Thanks Pete, I think I’m more persistent than skilled! I just keep clanging away , hoping to get lucky!

On the idle thingy....yeah, some days the idle is up and some days it’s down.

Yeah it’s funny, the idle on my XS2 is more affected by the bike getting hot, than my ‘77 is. The newer bike is pretty consistent. My old BMW airhead was that way, it was very cold blooded, if you made it idle well when it was cold, than the idle raced when it was hot.

 

[MaxPete]

hoping to get lucky!

Sorry Bob - after these two restorations, it ain't luck.

Its skill.

P

 

[TwoManyXS1Bs]

Bob, saw this in the "What have you done" thread, and was wondering.

Is your tach cable too long?

Yours.


Mine.

 

[Mailman]

Yours certainly fits better. I added a zip tie to the frame because I didn’t care for the way it looped forward away from the frame. I ordered the cable from Mikes. Here are some other XS2 reference photos.

 

[TwoManyXS1Bs]

I recall there were some questions about tach cable lengths in here a few years ago. I have no answers, but could use maybe an additional 1/2" in length on mine. I've had to put a little bend in mine, just below the instrument fitting. Something worth pursuing?

 

[Mailman]

I was looking for a good photo showing the original cable in place, but I don’t have one. I tore the bike down too fast. I still do have the original cable I could measure.

 

[TwoManyXS1Bs]

I'll pull mine (could use some cleaning/lube anyway), and post measurements here. Both inner and outer lengths. Maybe tomorrow...

 

[Jim]

I might have an XS1 tach cable 'round here somewheres... I'll look tomorrow.

 

[Mailman]

A study of tachometer cables.

Since 2M brought it up, and it seems I have the time to fool around with it I thought I’d dig out my original cable and do a little side by side comparo.

New cable on top, is one and a half inches longer than OEM

OEM cable installed in original routing location, coming up behind the triple tree.

And tucked up under the gas tank ( which I think would be prone to binding )

New cable installed in original routing location

New cable behind triple tree.

And finally the way I am choosing to run the new cable , routed in front of the triple tree and secured to the frame with a zip tie.

This routing gets the cable out of the way the best, and allows just enough slack at full left turn lock.

 

[TwoManyXS1Bs]

Ok, my old/original XS1B tach cable.

Cleaned off the old black vinyl paint, revealing the original grey. Had to tape it to a steel plate to straighten it out. Strange, the pic was crisp, somehow blurred during processing.


Cable outer lengths are measured from the cable sheath ends, attaching ferrules excluded. The cable inner is shoved in flush with the instrument end.


The cable outer sheath is just under 30".
The cable inner is about 1-1/2" longer.


A note on the seating bead.
Drive cable seating beads always go to the lower/driven end, opposite of the instrument. This not only establishes the technical/functional length, but also prevents the cable from settling too deep into the drive, and prevents its withdrawal during instrument servicing. Installed backwards, the bead will grind in/on the sheath's inner opening.

And, we're back to black.


It'd be nice if my cable was just 1/4" longer, at 30"...

 

[TwoManyXS1Bs]

The old parts lists show that we use the same cable, p/n 256-256-83560-00, later superceded to 256-83560-01.

I'm at a loss as to why your original cable (which appears shorter than mine) shows to be too long when installed...?

 

[Mailman]

The old parts lists show that we use the same cable, p/n 256-256-83560-00, later superceded to 256-83560-01.

I'm at a loss as to why your original cable (which appears shorter than mine) shows to be too long when installed...?

Yeah and I’m pretty sure it’s a factory cable. The bike only had 5000 miles on it.

 

[TwoManyXS1Bs]

My guess is your cable sheath may be 29-1/2", a bit shorter than mine.

Your cable is shorter, and looks too long.
My cable is longer, and looks too short.

The only differences I'm aware of are:
- Your cable routing would be shoved a bit rearward by the hydraulic manifold on the bottom bracket (triple tree).
- We use slightly different instrument mount plates. But your instruments look to be the same height as mine, comparing their spacing above the headlight shell.

I guess we'll see what Jim finds...

 

[Jim]

Inner drive cable.... a tad over 31 3/8"

Outer sheath.... 30"