Author Topic: Chain Thrown??? Not sure...  (Read 2717 times)

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Offline odin836

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Chain Thrown??? Not sure...
« on: February 28, 2009, 09:05:32 PM »
Engine has been pulled from the frame and mounted on the engine stand.
(Thanks to whomever originally welded steel tabs to bolt heads, makes mounting easier)

There seems to be some sort of gunk stuck to the block, where a chain possibly could have been thrown and repaired using some of that cold solder stuff...

What is the "BEST" solution to repair such damage???



CB750 K3 in pieces.

Offline mystic_1

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Re: Chain Thrown??? Not sure...
« Reply #1 on: February 28, 2009, 10:04:50 PM »
Well, you're in for a full tear-down if you want to really fix that.  You'll have to have the case TIG welded.  You may need to use a chisel to remove that stuff, depending on how well it's adhered.

Or you could leave it and cross your fingers.  Is it leaking?

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
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Offline odin836

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Re: Chain Thrown??? Not sure...
« Reply #2 on: February 28, 2009, 10:13:34 PM »
Yes, it had quite a build-up of oil, although it was hard to tell if this was 'leaked' from the engine or thrown from the chain.

I'd like to do a propper repair, as I'm planning on increasing engine capacity (836) and dont really want an issue further down the line.

Who typically repairs this type of thing?  Not your average mechanic I'll bet.

Cheers!
CB750 K3 in pieces.

Offline mystic_1

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Re: Chain Thrown??? Not sure...
« Reply #3 on: February 28, 2009, 10:24:51 PM »
You'd want someone whose done this sort of work before.

Might be cheaper/easier to find a set of replacement cases.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline bryanj

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Re: Chain Thrown??? Not sure...
« Reply #4 on: March 01, 2009, 06:26:27 AM »
BEST repair---New Cases
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Soos

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Re: Chain Thrown??? Not sure...
« Reply #5 on: March 01, 2009, 06:35:46 AM »
I agree.

Another motor is the best fix IMO.(cheaper and less time intensive as well)
It will cost you a trip to a bike boneyard or three, but you will be able to ride your stock damaged case motor while putting the 836 kit in the other motor.

Just check the new motor over well, make sure it's a good candidate.
:)



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vtwinjunkie

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Re: Chain Thrown??? Not sure...
« Reply #6 on: March 01, 2009, 07:47:15 AM »
If your going to get into another motor to bore ect. you might as well just get another motor and replace all seals and bearings while you have it torn apart

Offline 754

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Re: Chain Thrown??? Not sure...
« Reply #7 on: March 01, 2009, 09:43:46 AM »
As far as case damage goes, that is fairly minor.
Dont get too worried yet. Strip ogffwhat is on it, and see if there is an actual hole or chunk missing.

When that is the case, often globs of repair material get pushed inside.

 It appears the bottom case is OK, unless there is a small crack.

 I know of a member on here that I gave advice to that split the cases, leaving the topend on. Then removed some trans parts, got upper case welded, resurfaced it himself (after a pep talk),and has A LEAK-FREE HAPPY MOTOR....  for less than the price of main bearings and gaskets.

 Yours looks good, they often have chunks broken out on both cases..
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline mystic_1

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Re: Chain Thrown??? Not sure...
« Reply #8 on: March 01, 2009, 12:11:14 PM »
I agree with 754, that damage is minor compared to some things I've seen, first hand even.

I'm seeing two layers of stuff in the pic, looks like someone fixed a small hole, then it leaked, and either the same someone or someone else applied more goo trying to seal it up.  If it's already leaking, start digging and see what you find.  At worst you can apply some new goo yourself to keep it sorta sealed until you work up a replacement.

I've seen motors run with far larger repairs in that area, and hold together fine.  So long as you're not finding crap in the oil you're probably ok for a while.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline TwoTired

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Re: Chain Thrown??? Not sure...
« Reply #9 on: March 01, 2009, 12:21:55 PM »
About the oil you found...
You sure it's not from the chain oiler?
Some 750s have this device, does yours? 

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline mystic_1

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Re: Chain Thrown??? Not sure...
« Reply #10 on: March 01, 2009, 12:25:32 PM »
Yes it does.  You can see it at the center of the sprocket, the large hex nut with the screw in the center is the oil mech adjuster.  Turn the screw inwards to reduce or stop oil flow.  His looks to be most of the way closed if not completely closed.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline 754

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Re: Chain Thrown??? Not sure...
« Reply #11 on: March 01, 2009, 12:32:13 PM »
2 things with the patch.. It must be clean , if not it could still leak

 And you may want to add anchors.. easy to do..

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Mystic, I wood rather use the chickens altho a logistical harness nightmare,
cuz they would fertilize the soil for you, and eliminate a few bugs.. and chicken drumstix are tastier than oxen..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline odin836

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Re: Chain Thrown??? Not sure...
« Reply #12 on: March 01, 2009, 10:10:21 PM »
Thanks for the responses.

On further inspection, I agree with mystic_1, there looks to be two repairs done.

Seems both replacement and repair will work, based on your comments.

I'm a bit of a perfectionist, and never happy unless all is as it should.
That said I'll see what I can source locally from the graveyard.  It will be interesting to see what prices a complete motor will go for given all the interest in the 750s, the cost might decide the future of my current case... Graveyard or repair!

I'll keep you updated on how I go.

Cheers!
CB750 K3 in pieces.

Offline odin836

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Re: Chain Thrown??? Not sure...
« Reply #13 on: June 07, 2009, 05:20:40 PM »
Well its been a few months between drinks....

The case is apart and it looks like there are a few more "imperfections" with the engine case.
Whats the general opinion here, ignore, weld or seek a complete case replacement?


Engine Mount



Next to primary chain roller



External???


CB750 K3 in pieces.

Offline bucky katt

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Re: Chain Thrown??? Not sure...
« Reply #14 on: June 07, 2009, 05:30:14 PM »
new cases are what i would do, well new to you. i'm cheap as hell with some stuff but theres too much damage on those cases.
Of all God's creatures there is only one that cannot be made the slave of the lash. That one is the cat. If man could be crossed with the cat it would improve man, but it would deteriorate the cat.
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Offline odin836

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Re: Chain Thrown??? Not sure...
« Reply #15 on: June 07, 2009, 06:53:09 PM »
The hard part will be trying to find a set of cases here in Australia.
I notice there are currently 3 available on ebay in the US for a reasonable price.

Dont like my chances...
CB750 K3 in pieces.