Topic: 1977 Honda cb750K front/left Engine Mount Question.

[BenelliSEI]

I have more than a couple cb750s. My son and I ride regularly and enjoy these motorcycles immensely. I have a collection of Manuals, Books and Magazines that cover the history, maintenance and evolution of the SOHC CB750.
NEVER have I seen this particular design variance noted, photographed or explained. The left front engine mount (just below the exhaust port on the side with the kick stand) on almost all my SOHC cb750Ks include a cast lug, welded to the frame downtube. A bolt passes through it, and then into the main engine case (backed up by a captive nut). On my 1977 cb750K there is NO LUG on the frame. It has two small bushings welded through the frame. Attached by two bolts/nuts (that pass through the frame bushings) is a fabricated engine mount. At the engine end it uses the same “bolt to the main engine case”. Beautiful, separate bracket. As a BONUS, when removed, the engine tips forward a bit further, and is much easier to move in and out of the frame.
EVEN STRANGER, my 1978 , goes back to the welded lug, just like every other K0-K6 machine. Has no one else ever noticed! And why only on my 1977 cb750K7??
Cheers, John D

[beemerbum]

Have never looked closely at the area you are talking about on a 78. Very interesting. How about a couple close-up photos. of the areas? Awesome collection!

[BenelliSEI]

Thanks! I’ve been at it for a long time! Bought most of them for a few hundred dollars, when nobody cared. To be clear, the fabricated mount is ONLY on the 1977 model. I’ve seen one other, AND I have a spare mount that came with some junk I bought at a swap meet, so I know it’s not something somebody did! Weird.
I’ve read several detailed documents about changes Year to year, but never seen this mentioned. I’ll add some pictures over the next few days. John D.

[Bankerdanny]

That sounds like how the front engine mounts are on the 500/550. Looking at a picture of my '76 750F the left front mount is as you describe. I don't have any pictures of the left side of my '78F3 roller to see what it has, but the right side mount is the same triangle bracket with the tip bolted to the engine side and the wide flat side attached to the frame by 2 bolts that run through bushings welded into the frame.

*edit* you can make out the left side in the picture I attached, it's the welded bracket, not the bolt on like the right side.

[754]

 I am familiar with the mount, have only seen a few,not sure if 78 had them.
 The other variant, and I think they may be used  with that mount, is the serial number boss turned 90 degrees and closer to the middle.

 I even started building a billet motors mount for the odd mount, insane amount of work.
You can see it on left in pic.

[Bankerdanny]

I did find a bunch of photos on line of '77 750K's that show the left side with the same kind of bracket as you can see in the photo above, then when you search for '78 the engine mount is back to the welded style.

So it does appear to be a one-year anomaly. I wonder why they changed and then changed back.

[Erny]

If I understood well your question, I have the same like you - unusual left bracket on my K7 

see my old post - http://forums.sohc4.net/index.php/topic,171676.msg1998161.html#msg1998161

By the way beautiful collection of CB750s!!! Congratulation!

[BenelliSEI]

Great to have it confirmed by a few others! I will take a picture and post it next time I am in the shop. My question still holds: after reading all the EXPERT books. And analysis, why has no one ever added this obvious difference to Year by Year evolutions? Also, why the change? Did the 750A use this mount pehaps?? Any input most welcome! John D.

[Erny]

I can only comment that in my case it makes me difficult to fit standard crash bars, but now all OK after some adaptation.
But agree I did not find it in any documents...

[kmb69]

Great to have it confirmed by a few others! I will take a picture and post it next time I am in the shop. My question still holds: after reading all the EXPERT books. And analysis, why has no one ever added this obvious difference to Year by Year evolutions? Also, why the change? Did the 750A use this mount pehaps?? Any input most welcome! John D.

I did find a bunch of photos on line of '77 750K's that show the left side with the same kind of bracket as you can see in the photo above, then when you search for '78 the engine mount is back to the welded style.

So it does appear to be a one-year anomaly. I wonder why they changed and then changed back.

That's wild and a new one for me! The 1977 parts books online show the "original" style mount.

[Bankerdanny]

Hopefully Hondaman will weight in on this.

[BenelliSEI]

Today I took pictures! The first one is a spare mount, on the bench. The second two photos are of the mount, on my 1977 cb750K7. Ignore the chrome tube, it’s the end of a crash bar. Why is this mount (and the frame downtube) only modified for 1977?? My K8 is back to the usual welded lug on the frame. I have never seen this single year change documented anywhere....... how strange? John D.