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Discussion Starter · #1 ·
I am working on a 1978 cb400Tii, I have found the engine needs a new crankshaft and piston rod.

Is the connector rod for these models the same as any other CBs?

I am having a tough time finding a rod that isn't $180 because its OEM

Any ideas on what might work or where I could find a rod for not so much $$$

Land vehicle Vehicle Motor vehicle Motorcycle Mode of transport
 

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Some questions here, why do you need a new rod? Is the small end over the size limit? I you don't want to spring for a new one the only other option is a used one. Used parts can be OK provided the meet the specifications listed in the factory shop manual. One of the SHOC guys will chime in, but I would suggest starting the the Honda parts fiche and make a table comparing part numbers. Even with that there may be more interchangeability. The other thing is what engine do you have. Please post the serial number. It looks a lot like a 450 Nighthawk to me.
 

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All of the 78 and up 400 twins have the same engine. Any CB/CM 400 (78 and up) rod will work. You could find a used one on eBay.
 

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Some questions here, why do you need a new rod? Is the small end over the size limit? I you don't want to spring for a new one the only other option is a used one. Used parts can be OK provided the meet the specifications listed in the factory shop manual. One of the SHOC guys will chime in, but I would suggest starting the the Honda parts fiche and make a table comparing part numbers. Even with that there may be more interchangeability. The other thing is what engine do you have. Please post the serial number. It looks a lot like a 450 Nighthawk to me.
You're right, that engine looks a little out of place.

Zackery77: check on the left side of the engine, below the carbs where the cylinder meets the upper crankcase and check what it says there. If it is a 400 it will say 395CC, if it is a 450 it will read 447CC
 

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Discussion Starter · #5 ·
Ooops, pic is deceptive

Hey, you are correct. That engine is from a 1981 450 hawk. I got the stock engine, separate, when I bought the bike. That pic is from the day I unloaded it, I forgot that I hadn't swapped out the motor yet.

Compression was great but when you turn the crankshaft only one piston was moving, got it apart and the right side crankpin was unattached to the rod. So I found a new shaft and would like to get a good rod, so when I re-ring it, get a new timing chain and replace any other worn down parts, I can be sure I won't need to do much work on this guy (engine wise) for a long time.
 

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As with the 400's all the 1982-86 450's use the same rod. 400 rods won't work. The 450 engine started in 1982, 400's ended in 1981, so you might check the displacement tag on the cylinder to be sure you have a 450.
 

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The rod should not wear in any way, under normal operation. The bushings can get worn if the bike ever had too little oil. There are some cases where the rods get bent or have some failure, but not common in such a small stock engine. I think that replacing the small end bushing would be far cheaper than replacing the whole rod, and it would still be just as reliable. You probably do not want to replace the big end shells any way (because I don't think it'd do any good if you do not plan on regrinding the crankshaft).

Even if you can't find the correct bushing, any decent machining shop should be able to make one. The biggest problem is that after you insert it, you need the correct reamer (can be used by hand) to repair and finish the hole surface. But the same machine shop likely has one of the right diameter, or there are also other ways to do it if you have the right machines, so if they make you the bushing, they can probably also press it into the rod and ream it...
 

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Discussion Starter · #8 ·
Thanks for the details.

I should have explained a little more clearly what I am doing:
I Bought a 78 cb400TII with a 82 cb450 motor on it. The bike came with the stock engine and I am in the process of fixing several issues. Current one being that the connector rod on the left side of the bike has play in it. The bearing is sheered and the crankshaft is messed up pretty bad. I got a crankshaft and now I found a connector rod with bearing in place.

My next issue is the fuse holder clips are woefully loose and I will be swapping them out for a newer fuse block and going away from the bus fuses that were stock on the bike.

Once I get that settled; I have a headlight out, new tires to buy, and some work on the back brakes.

I will be glad to get this dude up and running. This bike rolled off the line about three months before I was born, I think it kind of cool we both showed up in late 1977 and have just now found each other!
 
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