Help I'm an idiot

Hello chaps.
Jonno from England here checking in for the first time.
Long time biker but a tad dim.
I seem to have acquired this little number and ain't too sure what it is.
Engine is a cb750 dohc rc02 which I'm ok with. Bike was registered in 88 in uk but built in 83.(Possibly imported?)
But what the heck is this frame.??
Number very faint but starts RC04-200.. I think it a cb 750 type but note the kinked back leg of the frame and the whole of the rear section seems to be as one, no welds!!! Shocks are not original but seem pointless at that angle. Anyway, now we've all got over Mr Trump being the most powerful man in the western world, let's get back to more important things. Can anyone help??? Where's the frame from!!! Night hawk, bol d or???
Thanks in anticipation. Jonno



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It looks like the OEM CB750 frame has been modified to shorten the rear end and increase the shock angle.

CB900 were SC01 I think and DOHC CB750K were RC01 and CB750F were RC04 according to mr. Google. F had 4 into 2 pipes with Euro styled tank/seat side covers and the K had a conventional tank and 4 pipes. I could not find an RC02 reference but that's probably because it was an overseas spec. 750.

I would doubt that the frame tube could have been bent with such a tight radius with aftermarket equipment, and that suggests it was cut and welded and welds ground down. An OEM frame seems to bend inwards at that point, so it's possible that the welder cut the frame above and below that point and rotated the tube

teazer said:

It looks like the OEM CB750 frame has been modified to shorten the rear end and increase the shock angle.

CB900 were SC01 I think and DOHC CB750K were RC01 and CB750F were RC04 according to mr. Google. F had 4 into 2 pipes with Euro styled tank/seat side covers and the K had a conventional tank and 4 pipes. I could not find an RC02 reference but that's probably because it was an overseas spec. 750.

I would doubt that the frame tube could have been bent with such a tight radius with aftermarket equipment, and that suggests it was cut and welded and welds ground down. An OEM frame seems to bend inwards at that point, so it's possible that the welder cut the frame above and below that point and rotated the tube

Click to expand...

Yes you could be right, I hadn't thought of that. Very neatly done too, much neater than the rest of the frame. I'm going to blast it so I may discover the cleaned off welding. Thanks.

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Looks like those aluminum panels that hold the brake lever and pegs were modified as well. Best to give the whole bike a good look over to get an idea on whats changed.

Good point. It looks like the PO cut off the passenger peg part and where the longer F model swingarm pivot passes through. They could be replaced I would think with a pair of stock CB750/900 footpeg brackets if the OP wanted to carry a passenger. It would need a longer F model swingarm pivot bolt and perhaps some spacers.