Topic: I know I know... but seriously. What's up with this serial number?!? CB750

[Tugboat]

I see threads like this all the time and think to myself - why don't they just look it up?

Well, tonight I pulled out the title to my 750 so I can go register it tomorrow. Lo and behold - it says 1977. I thought maybe it was a late-model 76F that got titled as a 750, so I go downstairs and look at the numbers:

Frame: CB750K2715601
Motor: CB750E-2715685 (the motor that came on it) and 2798806 (replacement motor)

Now, I can understand that maybe at some point the PO (or his PO) swapped out motors. But I'd always assumed I had a '76 F frame. See, I've got the longer swing arm, disc in the back, F tank & side covers and that weird junction box thing... But that's not what the frame stamp says! CB750Kxxx is a K frame, right? So what's up with that?!?

[Hinomaru]

Your frame serial number is legitimate and for a 1977 CB750 K model (not F) which was sold in the Canada market. Those Canada frame numbers are: CB750K-2709636~2728111

[Retro Rocket]

Your frame serial number is legitimate and for a 1977 CB750 K model (not F) which was sold in the Canada market. Those Canada frame numbers are: CB750K-2709636~2728111

I think thats an early F0 or F1 frame, look at the rear peg mount and the alloy bracket for the master cylinder, same as my F0

[Retro Rocket]

Just looked at mine and its a 76 and it definitely says "F" on the frame. Maybe yours has been retagged.....  Hmmmmmm

[david 750f]

Does the frame serial number from the VIN plate match the serial number that is stamped onto the other side of the steering head?
It sure looks like a 75/76F frame.

[Jerry Rxman Griffin aka MuthaF'er]

Yeah, check the stamping on the steering head for it's serial number. Let us know what it is. It sure looks like 75/76 F from front to back. If not then you have one helluva hybrid. The next question I'd ask myself is "why?". As long as it's licensed I might not want to look much farther. One of the bikes it's made from could have been hot provided there is a discrepancy between head stock and frame tag s/n's. The rear master is from approximately 2/75 F s/n 10154 through end of 76 F. The tank paint doesn't look original 77/78 either. The petcock would ID the tank as a 75/76 or a 77/78 TANK. A 77 F would also have a "HONDA" emblem on the seat tail piece along with MANY other differences. A 77 K would have some similar parts with a 75/76 F but not seat and tank. WTF?   

[Don R]

It's a 77 Fn'K I thought I built the only one! However, mine has the rear drum brake. Seriously, it sounds like a replacement title deal. As often as the titles get misplaced maybe someone took the seemingly easier route. I have considered a frame neck swap myself.

[754]

 Sidestand mounts are further back on 77/78 F frames.. this one looks like its further back.

 Not sure if they were on the first 2 years of F models.

[Retro Rocket]

Sidestand mounts are further back on 77/78 F frames.. this one looks like its further back.

 Not sure if they were on the first 2 years of F models.

First 2 model "F's" had the steel loop for the rear pegs, the others had an alloy bracket.....

[Terry in Australia]

Can you take the tank off and shoot a pic of the steering head area mate? I'm guessing someone's done a "cut and shut" on it, welding in the steering head from a K7. Cheers, Terry.

[KingCustomCycles.com]

My guess is they didn't bother cutting the neck out.  It is much easier to grind, restamp, and swap the rivets on a new plate.  Most just remove the plate and restamp.  This was really common in the 70's when chopper frames were available cheap and popular.  That is a OEM Honda "F" frame regardless what the vin or the title says.

[Tugboat]

So there's no plate on the neck.. only the stamped numbers. Will take a pic of the neck here in a bit.

[HonderCB]

theres also a difference in the LH side covers from the F0/1 to the F2/3.  The right sides are the same from what i can gather, but the left sides are different.  That could be a clue as to which generation of F the frame is.  I dont know what the difference is, probably the position of the mounting tabs.  Someone with more experience could probably tell you.

[754]

If the Visible numbers are on the right side of neck (sitting on bike).. it not good news..

[Spanner 1]

It's an F'nK Tug.... LOl...LOL...,LOL....

[Don R]

As posted above, it is an Fo/F1 frame. I know a guy with a car like that. One letter indicates a different model. Only an expert would ever notice. Probably not then.

[Tugboat]

Here's a pic of the neck. I was wrong - there is only a stamped plate rivetted to the frame. No sticker or whatever....

[754]

 It appears to be a numbered plate, or piece of another frame, riveted OVER the real numbers on that frame..
 I would stop putting money into that one.. and looking for a frame.
 There is a chance though that the real numbers if intact could be gotten in your name..

[KingCustomCycles.com]

Or the real numbers show it is stolen when you do the police check for the new title.  Leave well enough alone, if you have a title that matches that number, rock on as if it were as it were......:-)

[Tugboat]

Yeah, I've got a title already so I'm not worried about that. Just thought it was weird is all. And....... it IS weird!

[CycleRanger]

Could be a factory replacement frame. The bike may have been wrecked at some point.

[754]

Factiry replacements as far as I know are un numbered.. the whole idea of replacement is to put your numbers on it, then destroy the damaged frame.

 King, that is really poor advice.. altered numbers, run em.... lmao.
.
 Tug FWIW, till you  sort out the number issue, it is hard to put value on that bike.. You could get away with it 4ever. or you could run into a lot of hassles. . Hope it works out for you..

[KingCustomCycles.com]

Stamped a bunch of custom frames myself.  No problems, even with out of state police inspections and customs office on export.  Amen and Santee sent unmarked frames. The expectation was you would stamp the numbers from a donor bike into the frame and destroy the donor frame.  It was very common from the number of stamped frames I see.  I like OEM plates, but if a bike doesn't have one, it isn't a deal breaker. It will title, insure, sell, and ride, just like any other.

[crazypj]

The plate is only pop-riveted on, I would drill them out and take a look underneath for numbers.
 It could be a replacement frame and it's blank.
 I remember changing frames and we had a lot of trouble getting 6mm stamps, no way was the boss buying a set for one frame every year or two ( they were not cheaply available in 1977/78, no Harbor Freight, 'Made in China' stuff around)
Could be they had a plate made and just riveted it on?

[CycleRanger]

The plate is only pop-riveted on, I would drill them out and take a look underneath for numbers.
 It could be a replacement frame and it's blank.
 I remember changing frames and we had a lot of trouble getting 6mm stamps, no way was the boss buying a set for one frame every year or two ( they were not cheaply available in 1977/78, no Harbor Freight, 'Made in China' stuff around)
Could be they had a plate made and just riveted it on?

That's kinda where i was going with my post. 
I have a bike with a replacement frame and the new number is crudely stamped on the head, but as you suggest they may have made up the plate.
I'll bet there's nothing under that plate.