Topic: Disastrous first ride

[Henning]

Let's give the OP a chance to air his thoughts on how to proceed from this disaster. Hopefully he won't just be throwing in the towel.

He's already had an offer for some good casings (if not a complete bottom end), good advice on getting the casings welded, and there's always the option of a complete donor motor.

I don't want to turn this into a "sprocket" thread so I won't be responding to a couple of posts aimed at me.

[Turbogrimace]

My friend just did the same thing a few weeks ago. Drop the oil pan and recover the broken piecds, add a few slices of beer can and some jb weld. I know of several engined with many years and many miles on them that were repaired just like this. Not the perfect way, but it will certainly work if you prep the metal well.

Then 10 years from now when you decide to re hold the engine, you can have it welded hehehe.

[PeWe]

Talking about chain and sprocket that is not expensive in relation to what will happen when not change in time.
Here a photo of how my old front sprocket looked like when I removed it during the restore 2012. I bought in 1988. Stored in barn to end of 2009 when the bike for first time got a warm gararage.
I guess many should reuse it. I gave the bike new chain and sprockets. I changed from 17 to 18 when 17 screamed to much on 5:th gear

Chain clips.... The clip must be mounted in correct direction when the closed end into the driving direction. I had a chain where the clip disappeared...no problem since the plate inside of the clips was ver tough one to mount. A big pliear to press it in place.

The sprockets on photos whitnessed the chain snap off on Autobahn 1988...

[Bodi]

The sprocket is worn but not unusable. This sprockets are not the cause of the chain snap/disconnect. We haven't been told whether it broke or if the master link fell off. I would inspect the chain looking for acid damage, really severe rust, that the rollers are free and there aren't any seized links, and that the master link is secure with the clip the right way - but have no problem riding with it for testing and setup. I'd want a new chain and sprockets before saying "all done, ship it". Correct that as a rule chain and sprockets should be replaced as a set. Worn sprockets stretch the chain and stretched chains wear the sprockets.
Maybe modern super tensile chains don't stretch on our old low HP bikes, I haven't invested in any.

[mystic_1]

Well any way you look at it, THAT chain isn't going to get used again (one hopes) and new chain means new sprockets anyway, so i suppose in the end it's sort of moot


mystic_1

[754]

And member who need here suggested full disassembly  for welding.,
What I suggested was not fully taking apart.

 Take motor out, take the side cover parts off.. Remove case bolts that are on top side, then flip over and split cases...
 Then...degrease case and take to a good welder..who should clamp it to a plate...and of course. Would not even think of welding it oily..

[Retro Rocket]

Well any way you look at it, THAT chain isn't going to get used again (one hopes) and new chain means new sprockets anyway, so i suppose in the end it's sort of moot


mystic_1

exactly...

[ekpent]

Thumbs up to the OP for posting and maybe taking all of the roasting  --- He was a good guy for maybe telling all the folks who visit that bad things can happen quickly and some dreams and a lot of hard work and money can change quickly. Took some balls to bring it up.  I think it was a chain situation and a good reminder THANKS TO HIM that we all need to look at during the course of a resurrection. Hope your back on the road soon !!

[fmctm1sw]

Ekpent and others, I appreciate the kind words.  I've used this forum as a notebook of sorts to document the things that happen to my bikes.  Unlike paper and pencil notes, I figure I can't misplace anything I post here.  I put myself out there by documenting the good and bad stuff and I understand that I have to be willing to accept whatever comments come my way.  I don't let it bother me, it's just like any other form of media.  I post all kind of stuff on this forum because it's generally very active and you get a lot of feedback even on things completely unrelated to SOHC4 hondas.

I have some things I can act on and I thank everyone for the offers.  A couple offers for cases, advice on repairs, etc.  FWIW it's a K3 engine (serial CB750-22xxxxx).  I'll look back through the thread and maybe PM someone if they had a case.  There were cases listed on ebay as 1973 but the serial numbers don't line up to K3.  If anyone has a decent K3 lower case, I'd be willing to buy it (I'm in Florida).  I almost got my hands on a K7 motor locally but got outbid.  Based on searches I understand the sprocket offset issues with the K7/8 motors.

Documenting everything does have it's advantages.  Just the other day I saw a 350F on CL here (no pictures) so I emailed the seller and asked if it had the original exhaust.  When he sent me a picture of it, I noticed a repair done on the red wire from the rectifier.  It turns out this was a member's bike that I worked on a few years ago.  I gave the guy exact dates and a description of what all I did.  It led to some conversation on old bikes and a, "If I can't get what I want out of it, I'll call you." 

P.S.
If anyone is going to Barber's, bring me a motor...   

[madmtnmotors]

I'm in Saint Cloud, just South of Orlando. I've got a couple of cases, I'll let you know after I check the numbers to make sure they are of the correct vintage.

[fmctm1sw]

I'm in Saint Cloud, just South of Orlando. I've got a couple of cases, I'll let you know after I check the numbers to make sure they are of the correct vintage.

He might be closer to Bill Benton... Pensacola is a LONG way from anywhere else in FL!

+1.  I'm closer to Alabama than anything but may be planning on a trip to Busch Garden's that way.  Or maybe 6 flags in Atl in the next few weeks..

[Powderman]

I'm in Saint Cloud, just South of Orlando. I've got a couple of cases, I'll let you know after I check the numbers to make sure they are of the correct vintage.

He might be closer to Bill Benton... Pensacola is a LONG way from anywhere else in FL!

+1.  I'm closer to Alabama than anything but may be planning on a trip to Busch Garden's that way.  Or maybe 6 flags in Atl in the next few weeks..

Bill Benton is about a half hour from 6 Flags.

[Duanob]

My friend just did the same thing a few weeks ago. Drop the oil pan and recover the broken piecds, add a few slices of beer can and some jb weld. I know of several engined with many years and many miles on them that were repaired just like this. Not the perfect way, but it will certainly work if you prep the metal well.

Then 10 years from now when you decide to re hold the engine, you can have it welded hehehe.

That will probably be the fastest way to end up in the "Horrible PO Stories" thread.

[Restoration Fan]

Bill Benton is about a half hour from 6 Flags.

More like just over an hour but your point is valid.

[Ujeni]

I think you will find that it is cheaper to have the case repaired than to buy a replacement engine. Replacement engines will likely need new seals and bearings (plus gaskets etc). Find a good welder and they should be able to do it for less than $200 I would bet.

If there is no damage to the top case, you are in luck. You can remove the engine, flip it over, and only take off the bottom case. The top end stays together.

I have a sandcast CB750 that had this issue. The case was fixed and it works perfectly.

Don't feel bad. This was VERY common with CB750s. The engine was stronger than the chain technology of the time. As others have said, modern chains won't have this issue.