On the road again at 40.............the bike that is

Yes, I think you're right 5twins. I do check it often, and backing off the cover may just loosen it again when checking. As far as my abilities allow, I'm quite sure a stretched cam chain is the root of a lot of my problems.

Age for sure is enough of a reason and I would think the fact that it sat unattended for 9 years is a huge contributing factor.

Am watching for an upgrade on the tensioner for this 77D and for my 78E, waiting in line. Will ask for lot's of pics this time. Lol.
 
Hi Robin/All:
Yup - I can't disagree that there's no harm in a top end job. You'll likely get more power, better starting and you'll use less fuel and oil.

Plus, you'll learn something and gave some fun!

Pete
 
Coupla old excerpts to add to your knowledge base:

1. I've seen this high idle thing happen on engines that get low compression when hot. Difficult to explain, but, a funny balancing act occurs when low rpm idle settings (enough to keep it running) become too much at higher rpm, because the "effective" compression at those higher rpms is also higher. Internal engine loading also changes with lower compression at lower rpms, reducing the natural loads that slow an engine down.

2. Worn engines with low compression often display a hanging idle. The compression loss reduces the engine's internal friction, so to speak, and it rotates more freely. The compression loss also reduces the power output, requiring a little more throttle to idle. But, as the rpm rises, the compression loss has a lesser effect on power output. This relationship of power demand vs rpm, and power availibility vs rpm, defines the stability of the idle. Kinda hard for me to explain, it's like the difference between dynamic stability and dynamic instability in airplanes.

(Pause for head rattling...)

Your compression numbers aren't bad, so the above junk may not specifically apply. Just more stuff to contemplate.

My XS1B's timing chain is quite stretched, the cam is at least 10° retarded. Have to employ some unorthodox tuning tricks to get a stable idle. That'll change when I get around to replacing it. So, expect some differences in your tuning after you've replaced your timing chain. Things should actually get better...
 
Hey thanks 2M, I'll chew on this a bit....lol.

5twins does have me wondering. Is my compression good because it's good or because it's adding oil where it shouldn't be?
A cause and effect thing.

Time will answer this question.

TwoManyXS1Bs said:
Bottom line: Do YOUR thing...
Click to expand...

Thanks for that.
Reminds me of a question that must be asked of new cedar strip canoe builders.
"Are you building this because you love to build things and want to create a piece of art, or are you building this because you want a boat to paddle?"

After all this work, I'm going to enjoy it while I can for this season, which will all too soon end here. Keep a careful eye on things, and then enjoy a fun winter project.
 
Enjoy the chew, Rob. Be sure to spit it out when it tastes funny.

robinc said:
...Is my compression good because it's good or because it's adding oil where it shouldn't be?
A cause and effect thing...
Click to expand...

Another shop quickie. But you need stuff to compare with. Feeling the "engine braking". A healthy engine gives significant engine braking. The loss-of-compression engine tends to coast longer...
 
After reading all the comments here about adding a voltmeter I knew I wanted to do that, so I put one on last year when I was doing resto work. I liked the idea of a old school analog gauge for a triple gauge look setup so I got a 2” one. I had seen RG's analog gauge, wanted to do something similar, but didn't think of the fact that there wasn't enough clearance above the crown nut.

So I picked up a couple motocross handlebar risers, added some standoffs, made up a mounting plate out of ⅛” aluminum plate and bent up a case out of aluminum flashing material.

IMG_20170517_155941.jpg


You guys are so right, what peace of mind these give you. Until…….......…..it stops working. Last weekend on the way to meet Pete and Lakeview, took a quick glance and the needle is buried at 8 volts. Immediate panic.Then realized, she's running fine, must be a loose wire, pulled over and did the headlight check, looks OK. Carried on.

At the time I did this job I didn't have a good crimper so I just soldered the connections. One of my soldered connections was broken. I figured the old paint shaker had vibrated it enough to break. So I put my multi meter across the gauge, sure enough, I'm to blame for letting the smoke out. I don't think I had enough clearance for the gauge bolts to the crown nut and they grounded and shorted out. I guess I didn't trim them short enough. Should have shrink wrapped them too.

Good thing actually that they were soldered and not crimped. That solder joint acted as a fusible link and saved blowing the main.

I pulled the headlight, cut and crimped on good connections and added a mini fuse holder inline just to be sure.
Found another analog voltmeter cheaper than a digital one, so since I already made the case and mount, I'm riding with heightened anxiety and waiting on that slow boat from China.

I commented a few days ago in gggGary's "81 Wake up from the dead" thread (sounds like a good name for a band) that:

“My speedos' shakin' like a dog crappin' razor blades.” Led to some good discussion on solutions and some great ideas.

So when I was in the neighborhood figured I'd drop the headlight bucket and do something about it. Similar to Bob's (Mailman's) suggestion found that some 1/4” rubber grommets would cover the 7mm upper shoulder on the bolt allowing a 5mm stainless washer and acorn nut to cinch them up.
Could have just slapped the old acorns back on but I thought it would be nice to have some ‘shiny new nuts’.


IMG_20170803_135622.jpg


They're a little taller than the stock ones and my A/R eye notices those little details, but I'll deal with it.
 
Last edited:
Looking good Robin, did you order your new gauge from Banggood? Can't wait to see the new gauge installed.
 
TwoManyXS1Bs said:
This relationship of power demand vs rpm, and power availability vs rpm, defines the stability of the idle. Kinda hard for me to explain, it's like the difference between dynamic stability and dynamic instability in airplanes.

(Pause for head rattling...)
Click to expand...

OK, let me see if I'm getting somewhere on this 2M.

In a healthy engine we have a designed demand and supply equilibrium, 'dynamic stability'. In an aircraft 'statically and dynamically stable'.

In an unhealthy engine similar to mine, engineered internal tolerances are out of spec, (worn oversize), therefore designed resistances aren't being met, leakage occurs resulting in power loss. Less available power due to lower required compression than the applied load demands, the 'dynamic instability', then requires compensation or a boost somehow. The only way to do that is to artificially increase power output by increasing rpm's with an unnaturally high idle setting.

The demand/availability relationship instability being compensated for with higher idle speed settings is overlapping at higher engine speeds as well supplying more power again artificially or unnaturally, but with less impact at higher rpm's.

A weaker engine due to low compression can't provide the 'resistance'; required to 'brake' itself. This abnormal extra power boost is pushing a weakened engine beyond it's ability to oppose it, rpm's hang until this extra out of spec supplied power is removed somehow.
This is achieved by turning idle speed down to lower than normal forcing a dynamically unstable engine as close to a state of dynamic stability as can be achieved in it's unhealthy state. Once equilibrium is restored at a lower demand, lower rpm state, idle speed can be increased to 'normal' creating a temporary apparent state of dynamic stability at current demand/supply conditions. But, this new normal is actually achieved with a boost of power. Cycle repeats.

Or something like that.

TwoManyXS1Bs said:
Leaking rings will sound like a lizard hissing in a garbage can.
Click to expand...
TwoManyXS1Bs said:
*Gads*, how does one explain these kind of things?
Click to expand...
TwoManyXS1Bs said:
A healthy engine gives significant engine braking. The loss-of-compression engine tends to coast longer...
Click to expand...

Couldn't hear any lizards in my cans, however, I discussed these tests with my XS buddy who had it out for a good spin. He's had a few bikes, his last being a 'Busa" which is somewhat different :D. He said he remembers feeling a lack of engine braking and more a feeling of coasting, so who knows. My 78E isn't roadworthy yet so can't do a comparison.

I did do a 'Let's try this test' though.
Pushed the kick starter by hand with plugs in on this bike and my 78E. (Which tested at 150 psi each side).
There is significantly more compression to push through at the top of the stroke on the 78.

I guess the only way I'll know rings/pistons condition for sure is when we get in there.
 
Last edited:
Robin that was a very thoughtful analysis ....of a very smart explanation.
Seriously, I get it, that makes sense. So this hanging idle, when hot, thing of mine is likely a condition that is caused by loss of compression at the root of it all. That sounds reasonable. Harmony ( and my idle) will be restored when the engine is in proper balance again. Really it's the whole package, compression , proper carb settings, lack of intake leaks. I've often wondered why the first XS650 I had , back in the 70's when it was new , just ran so good without me ever having to mess with anything. It was because nothing was worn out yet. Over the last 40 years there are so many components that have worn out and rubber parts that are dried out, shrunk and cracked and electrical components that don't work as well as they did 40 years ago. Our bikes have been constantly tweaked and adjusted to compensate for these failings. All those tweaks come at a cost of something else being a little out of balance.
image.jpeg
 
robinc said:
A weaker engine due to low compression can't provide the 'resistance'; required to 'brake' itself. This abnormal extra power boost is pushing a weakened engine beyond it's ability to oppose it, rpm's hang until this extra out of spec supplied power is removed somehow.
This is achieved by turning idle speed down to lower than normal forcing a dynamically unstable engine as close to a state of dynamic stability as can be achieved in it's unhealthy state. Once equilibrium is restored at a lower demand, lower rpm state, idle speed can be increased to 'normal' creating a temporary apparent state of dynamic stability at current demand/supply conditions. But, this new normal is actually achieved with a boost of power. Cycle repeats.
Click to expand...
None of that happens :)
 
Well, I don't know Bob, maybe I'm out to lunch (xjwmx thinks so....lol), but I was trying to wrap my head around what 2M was saying.
Got stuck in 5th at 5000.

Tried to put into my words what I thought I was thinking at what he was saying.
Mailman said:
It's probably just the wine. I won't remember this in the morning. o_O
Click to expand...
Yup, me either.
 
robinc said:
After reading all the comments here about adding a voltmeter I knew I wanted to do that, so I put one on last year when I was doing resto work. I liked the idea of a old school analog gauge for a triple gauge look setup so I got a 2” one. I had seen RG's analog gauge, wanted to do something similar, but didn't think of the fact that there wasn't enough clearance above the crown nut.

So I picked up a couple motocross handlebar risers, added some standoffs, made up a mounting plate out of ⅛” aluminum plate and bent up a case out of aluminum flashing material.

View attachment 103941

You guys are so right, what peace of mind these give you. Until…….......…..it stops working. Last weekend on the way to meet Pete and Lakeview, took a quick glance and the needle is buried at 8 volts. Immediate panic.Then realized, she's running fine, must be a loose wire, pulled over and did the headlight check, looks OK. Carried on.

At the time I did this job I didn't have a good crimper so I just soldered the connections. One of my soldered connections was broken. I figured the old paint shaker had vibrated it enough to break. So I put my multi meter across the gauge, sure enough, I'm to blame for letting the smoke out. I don't think I had enough clearance for the gauge bolts to the crown nut and they grounded and shorted out. I guess I didn't trim them short enough. Should have shrink wrapped them too.

Good thing actually that they were soldered and not crimped. That solder joint acted as a fusible link and saved blowing the main.

I pulled the headlight, cut and crimped on good connections and added a mini fuse holder inline just to be sure.
Found another analog voltmeter cheaper than a digital one, so since I already made the case and mount, I'm riding with heightened anxiety and waiting on that slow boat from China.

I commented a few days ago in gggGary's "81 Wake up from the dead" thread (sounds like a good name for a band) that:

“My speedos' shakin' like a dog crappin' razor blades.” Led to some good discussion on solutions and some great ideas.

So when I was in the neighborhood figured I'd drop the headlight bucket and do something about it. Similar to Bob's (Mailman's) suggestion found that some 1/4” rubber grommets would cover the 7mm upper shoulder on the bolt allowing a 5mm stainless washer and acorn nut to cinch them up.
Could have just slapped the old acorns back on but I thought it would be nice to have some ‘shiny new nuts’.


View attachment 103942

They're a little taller than the stock ones and my A/R eye notices those little details, but I'll deal with it.
Click to expand...


Hello Robinc, that is a nice clean mount for the voltmeter. Do you have any other pics of the install/ setup?

I've always like the idea of an analog gauge (fits better with the age of the bike vs digital) but was always stumped with location and placement. Any gauge I've come across is 1) really deep and 2) a shroud/ housing needs to be fabricated.
 
Hey Sed27. Thank you. Out and about, checking in on my stoopid phone. Ya sure, I'll add a post of all the pics and info later today or tonight.

BTW, your beautiful restomod has inspired me for what will be my next, next project. Have to figure a way to get that purchase past the 'head of the finance committee'.
 
robinc said:
Hey Sed27. Thank you. Out and about, checking in on my stoopid phone. Ya sure, I'll add a post of all the pics and info later today or tonight.

BTW, your beautiful restomod has inspired me for what will be my next, next project. Have to figure a way to get that purchase past the 'head of the finance committee'.
Click to expand...

Haha. I also have a Head of Finance that can't fathom why I would want 2nd project, when I already "own perfectly good morcycle"

Thank you for the kind words on my build.
 

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