Topic: RE: CB750 K5 or K6 Engine

[chewbacca5000]

I have a couple lower ends and can't determine from hondachopper.com as they serial numbers seem to overlap.  Are these K5 or K6

1st is CB750E-2454190
2nd is CB750E-2507472

Edit: Never mind I was reading the chart incorrectly they are K6

[Dream750]

You actually have two different 750 engines as Honda throws us a curve ball with their model/year serial numbering sequence.

CB750E-2454190 is a 1976 K6:

http://www.sohc4.net/cb750k-serial-numbers/

CB750E-2507472 is a 1975 F0:

http://www.sohc4.net/cb750f-serial-numbers/

I double checked those serial numbers using the Honda published ID guide and they are confirmed correct:

[chewbacca5000]

You actually have two different 750 engines as Honda throws us a curve ball with their model/year serial numbering sequence.

CB750E-2454190 is a 1976 K6:

http://www.sohc4.net/cb750k-serial-numbers/

CB750E-2507472 is a 1975 F0:

http://www.sohc4.net/cb750f-serial-numbers/

I double checked those serial numbers using the Honda published ID guide and they are confirmed correct:

Thanks for the information that is very good to know.  So now which one is a better engine?  Also is the trans the same on both.  If not which one is better tans wise?

[Jerry Rxman Griffin aka MuthaF'er]

Agreed.

The 75 F engine is considerably stronger and the tranny has better gearing for acceleration. If you can find the top end to it with the 392 head and 392 pistons I'd use that combo. The head and pistons both have 392 cast on them. The difficulty would be IDing the 392 cam however. If you had original cams that you know are original you could visually ID them.

[chewbacca5000]

Agreed.

The 75 F engine is considerably stronger and the tranny has better gearing for acceleration. If you can find the top end to it with the 392 head and 392 pistons I'd use that combo. The head and pistons both have 392 cast on them. The difficulty would be IDing the 392 cam however. If you had original cams that you know are original you could visually ID them.

Pretty sure I have a F head not sure what year it is.  Came with the bottom end so it might be a 392.  It's a full hemi with a 64mm high compression pistons.

Not so much worry about making power just holding it.  This summers engine project is to learn transmissions.  Thanks for the reply.  Sounds like it might be worth messing with after all.

[Jerry Rxman Griffin aka MuthaF'er]

A '392' would be found on the top fin intake side by #3 in the middle.

[lwahples]

Cool! I just learned a bunch.

[chewbacca5000]

A '392' would be found on the top fin intake side by #3 in the middle.

I checked it is and no 392.  If it was there all the repaints have filled it in.  Just HM X 7.  I am thinking it is a K7 head it has the studs in the exhaust.  Hope it will bolt together ok.

Thanks Jerry.

[Jerry Rxman Griffin aka MuthaF'er]

A '392' would be found on the top fin intake side by #3 in the middle.

I checked it is and no 392.  If it was there all the repaints have filled it in.  Just HM X 7.  I am thinking it is a K7 head it has the studs in the exhaust.  Hope it will bolt together ok.

Thanks Jerry.

K7 and K8 are 392 also and have the '392' cast into them also

[754]

All 77$78. Motors have studs..but starting in 75 the F and A probably started using them ..but no K. Model