My What Am I Getting Myself Into Combat Build Thread

jbruney said:
Tear it down no because still doesn't use much oil and it makes plenty of noise when running, so it must be okay. Right?
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Absotuvely. Only tearing mine down because i'm bored.
No seriously, i was only getting 90 psi in the right cylinder. Plus the electrics were shot.
And i was a little bored ;)
If it makes the right sounds and doesn't stain the sheets, don't mess with it
 
Mine is running quite good so I'll not dig until I see it fade, but it is an old mule of an 850 not a racehorse combat.... A compression check is a frightening concept because it kicks over like an old Honda 50, or feels so to me. Good fortune on your adventure and may your expenses be low.
 
8:1 don't take much of a kick. Always been easy since '78. Anyway dumping the old AAU really softened it up a bunch.
 
Always been easy since ‘78....?

Your right leg may have had more oomph 42 years ago ?!

IF the CR really is 8.1 (mine was closer to 7.1) and IF the motor is nice n tight, an 850 twin should still require a nice firm swing.
 
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Perhaps I just don't notice it..... A labor of love you know. More like a slightly vigorous straightening of my leg..... She needs an oil change more than my twitchy fingers digging through the gutty works to be sure.
TomU appears to be diving in and taking no prisoners on this project which is certain to produce a winner.
 
Continuing with the "if I did it again" theme I say do the bike up without any cosmetic intervention. Get it running right
and find out if the frame, brakes etc feel correct. After that is good, wait until seasons end and then pull the powerunit and
have the frame tank covers etc beautified. I wish I had the frame checked but I had no idea where to go unlike now.
 
The main issues are low compression on the right cylinder, melted wiring, and frozen front caliper and MC. Not sure about the gearbox.

Pulled the head off (which was somewhat easier than the oil tank/horn, but not by much). I fear putting it back won't be near as easy

Carbon fouled...

IMG_1480sm.jpg


Gasket looks ok

IMG_1501sm.jpg


Pistons are fouled as well, but the cylinders look good (no gouges, specks are dust). Not sure how worn they are until i can mic them

IMG_1493sm.jpg


IMG_1497sm.jpg
 
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The low compression was on the right cylinder (90 psi). It looks like the exhaust valve on that side ran hot. Wonder if that could be a contributing factor. All other valves look carbon fouled, which could bleed compression, but the left cylinder measured good (150) and that's pretty fouled
 
Definitely paint it, rattle can and keep going with the rest of your build. Cj
 
Bet that one is going to be an easy fix if the boogers don't show soon..... Well easy compared to most anyway. I'll try to remain optimistic enough for several of us.
 
I'm reluctant to say this, but what the heck.

Kinda looks like all it needed was the head retorqued and the electrical wiring repaired. I don't think the head gasket on the right cylinder was perfectly sealed based on the pics, but I could be seeing a shadow on the cylinder deck in front and right of the right cylinder and not a dark stain from uneven torque and the exhaust heat trying to get out. The cylinder wall I can see looks good. I would not tear it down further unless you want to make some performance part changes. For example, installing a different cam.

If you are going to ride it, you might consider getting the head surfaced if needed, putting bronze guides in it, checking the condition of the rockers and spindles (R&R as necessary), and doing a basic valve job with new Black Diamond valves. Clean up the head of course. If you are going to sell it as a survivor, just clean it up, put it back together, and write up the ad.
 
the right exh valve looks more like i would expect to see in a normal engine and the left is is more on the rich side.

TomU said:
The low compression was on the right cylinder (90 psi). It looks like the exhaust valve on that side ran hot. Wonder if that could be a contributing factor. All other valves look carbon fouled, which could bleed compression, but the left cylinder measured good (150) and that's pretty fouled
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Schwany said:
I'm reluctant to say this, but what the heck.
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Coulda, Shoulda, Woulda comments are welcomed :)

Schwany said:
Kinda looks like all it needed was the head retorqued and the electrical wiring repaired.
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Probably. Should have retorked the head to see if that would help the compression. The gasket is fiber

Schwany said:
I don't think the head gasket on the right cylinder was perfectly sealed based on the pics, but I could be seeing a shadow on the cylinder deck in front and right of the right cylinder and not a dark stain from uneven torque and the exhaust heat trying to get out.
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Think it's a shadow. It appears evenly colored

Schwany said:
I would not tear it down further unless you want to make some performance part changes. For example, installing a different cam.

If you are going to ride it, you might consider getting the head surfaced if needed, putting bronze guides in it, checking the condition of the rockers and spindles (R&R as necessary), and doing a basic valve job with new Black Diamond valves. Clean up the head of course. If you are going to sell it as a survivor, just clean it up, put it back together, and write up the ad.
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My guess it's in pretty good shape (only has 15k on it), but since i'm into it, may as well do some upgrades to improve the internals (as you mentioned). Once i get it back together, don't want to have to tear it down again in my lifetime (my car is there for that) and i don't plan to ever sell her. That said, i will have all the tools....

bill said:
the right exh valve looks more like i would expect to see in a normal engine and the left is is more on the rich side.
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Yeah, that's what it looks like to me, but why the low compression on that side. Will be measuring the cylinder soon
 
Schwany said:
Kinda looks like all it needed was the head retorqued and the electrical wiring repaired. I don't think the head gasket on the right cylinder was perfectly sealed based on the pics...
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A composite head gasket loose enough to lose compression, would burn thru pretty darn quickly, and in an obvious fashion... (I believe)
 
Have you rotated your crank (protect the rods with toilet paper tubes) and looked at ALL of your cam lobes yet? How do the cam followers look?
 
grandpaul said:
A composite head gasket loose enough to lose compression, would burn thru pretty darn quickly, and in an obvious fashion... (I believe)
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What you are saying sounds logical to me. The composite gasket probably would have been in rougher shape to support my guess.
 
Schwany said:
What you are saying sounds logical to me. The composite gasket probably would have been in rougher shape to support my guess.
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I'm interested to see what the cam lobes all look like. I've got a hunch...
 
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