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Discussion Starter · #1 ·
Finally got the gumption to pull the engine from the wife's 78 to fix a nasty oil leak from the head gasket, and do the solid balancer conversion.

Much to my dismay, no more than 30 minutes in to disassembly, and I find this... Auto part Engine Metal Automotive engine part z

Sooo, suggestions here?

I know it's shot, so I'm currently looking for a complete head, unless there's another -more readily available- swap or upgrade.

There's currently a complete head on eBay. Said to be from a running bike. But honestly I'd love for someone else here to look at the provided pictures to tell me if they think it's in good condition.

I've also posted in the "parts wanted" section as well.

Thanks to everyone for their help.


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Severe oil starvation. You definitely want to check the rod and main bearings since there's this damage.
How is your cam and the rocker stands? Any damage?
There's several listed on eBay, some with good photo's and some not.
Of all the ones listed this one is the most complete and photo's look good https://www.ebay.com/itm/Honda-1980...ash=item5d699f7a83:g:fu4AAOSwmLlX7ygu&vxp=mtr
If the cam is damaged but the rockers are good this one will be good. https://www.ebay.com/itm/oem-CYLIND...ash=item3d4187f5e5:g:D90AAOSw2rFZbECa&vxp=mtr
If cam and rockers are good then this one. https://www.ebay.com/itm/1980-Honda...ash=item33b1d88c28:g:BWYAAOSwll1Wu7C6&vxp=mtr
 

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Discussion Starter · #3 ·
Severe oil starvation. You definitely want to check the rod and main bearings since there's this damage.
How is your cam and the rocker stands? Any damage?
There's several listed on eBay, some with good photo's and some not.
Of all the ones listed this one is the most complete and photo's look good https://www.ebay.com/itm/Honda-1980...ash=item5d699f7a83:g:fu4AAOSwmLlX7ygu&vxp=mtr
If the cam is damaged but the rockers are good this one will be good. https://www.ebay.com/itm/oem-CYLIND...ash=item3d4187f5e5:g:D90AAOSw2rFZbECa&vxp=mtr
If cam and rockers are good then this one. https://www.ebay.com/itm/1980-Honda...ash=item33b1d88c28:g:BWYAAOSwll1Wu7C6&vxp=mtr
Cam is trashed on that end. Rocker tower at same location as well. Since there's that much, I'd rather just get something complete, to know condition of everything.

I was unaware of what would be compatible as a bolt on for this. You're saying CM400A would be same head, no other mods?

The CB400A set I saw was 99.95, complete.

Thanks for the quick response.

I was going to save splitting the case until this was taken care of, but if you think it best, I'll fab up a stand, flip it, and start peeling into it.


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Discussion Starter · #5 ·
When it rains, it pours.

Just started taking bits off to prep to flip the motor and split the cases. In doing so I pulled the orifices that feed the head, and found this..... Screw Auto part Tool accessory Cylinder Hardware accessory

MUY NO FLIPPIN BUENO.

Since the last thing in line before this is the main, I am none too pleased at this point. Oddly enough, this feeds the OPPOSITE side of the head of the cam that was damaged.

Greeeeeaaaaaat.

What is even the course for a trashed main? Regrind and oversized bearings?

No telling what I will uncover as the weeks progress.


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Well this absolutely sucks. There are no oversize bearings made for these engine. Honda was a replacement part only situation. That's not to say that bearings can't be fitted, just a case of lots of research to find some that fit the case bore properly and see what the ID of the crank would need to be turned to. I've never heard of someone doing this. Cheaper to replace it.
I'd hold off on ordering any parts until the engine is completely apart and you know what you're dealing with. It may be a case of replacing the engine.
 

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Discussion Starter · #9 ·
Yup, that's where I'm at. I'm even looking into a full replacement. Cost of head, gaskets, valve job, blah blah. And now this....... may not even pop open the cases at this point. What was supposed to be a deal up, and swap balancers has turned into a MESS


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I think a full replacement would be the way to go. Maybe a cm motor since there are more of them. Some of the replacement parts to rebuild the cb 400A motor are very rare and hard to find.

Just a thought .

Bill


The main reason Santa is so jolly is because he knows where all the bad girls live.
 

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Discussion Starter · #11 ·
I HAD two options open in CL. One a motor only with carbs advertised from a 78. That one didn't have contact info in the add, and after REPEATEDLY sending generic emails with no response, I see the add was pulled today. The other is a 79. Don't know if that's a CM or CB. SAYS ran couple months ago, now no spark. I did the conversion on my 78 to use the 400T flywheel and some guys homemade deal, but don't know if that'll swap over. And I'm generally NOT in the practice of buying anything I haven't heard run, or at least TRY to run with carb clean.


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The only real difference between the CB400A and the CM400A is the frame, engines are identical in every respect. I would suggest NOT throwing out your old engine. Tear it down as time allows and look at how it's built and figure out why things are built the way they are for your own education. Also save whatever good hard parts there are like the crank, rods, cylinder or whatever. Someone will need them in the future.
 

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Discussion Starter · #13 ·
Scored a bastardized "cafe project" 79, with the story "...it ran four months ago, but it just doesn't have spark now..." and aside from the flywheel covered in scale, the engine was pretty clean.
Bolted it up last night, swapped my ignition system over, and so far so god. With just a little squirt of carb clean it starts on first hit. Will be bolting up carbs tonight, and exhaust. Hope to button it up enough to let it idle to hear how things are working in there. Possibly a spin in the yard. Fingers crossed!! I do still intend to split the case on the original motor just to see -if I get the wild hair- if it's salvageable. No hurt in having a spare, or indeed edumacating myself on its guts.


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Discussion Starter · #14 ·
So, much to my udder amazement and delight, the 78 seems to be unscathed by the aforementioned offending bits. Crank has no bearing damage, oil pump seems clear and damage free as well as any other "orifice" I've run into this far. I am indeed amazed! As I'll be redirecting this motor, and replacing the balancers as per my original plan... I'm going to have questions. First, for now, will be if these balancer guides look ok for re-use, or if they're shot..... Bicycle part Auto part Engine Vehicle Metal Machine Machine tool Auto part Auto part Bicycle part Vehicle Bicycle part Auto part Engine Vehicle Metal Auto part Gear Automotive engine part Transmission part Engine

Thanks again!


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These are the chain slipper part # 13430-413-000 $99.50 at CMS and chain plate guard part # 13431-413-010. currently unavailable. I hope you can find them or a good used pair. I replaced mine last summer and had a tough time finding them. Maybe another member can put you on a pair.

Good luck, Bill
 
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