Topic: 77 CB750A most like what other model?

[stresssolutions]

Hey, I downloaded the CB750K service manual, has lots of good info, of course.  But, I wonder is the A most like the F, K or what other model? 

Any idea what specs will be different, what if any tune up parts will be the same or different?  Capacites?  For example, does the A use engine oilin the transmission?  There is a sticker next to the dipstick that says use engine oil only...BTW it seems to be identical to the dipstick used on the transmission of my 88 Honda Accord.

I appreciate any and all replies....unless the reply is rude. 

[Sam Green Racing]

The Auto motor is nothing like the Ks or Fs.  The compression ratio is only 7.7 compaired to the Ks 9, the F1s 9.2 and, the F2s 9.

The power is only 47bhp compaired to the Ks 67 and, theF2s 73.

It makes this power at just 7,500rpm compaired with the Ks 8,000, the F1s 8,500 and, the F2s 9,000.

The torque is only (kg-m) 5.0 at 6,000rpm compaired to the Ks 6.1 at 7,000, the F1s 6.1 at 7,500 and, the F2s 6.4 at 7,500.

I think the carbs and the heads inlet tracts are smaller and perhaps the valves also.

Just tune your motor to the settings as laid down in your workshop manual.

Sam.

[rbmgf7]

i got ahold of a 750A frame and engine. my buddy took the engine but i got the frame. the frame has an advantage over other 750 frames since it has the hump over the valve cover. therefore, allows the person to work on the head while the engine is still in the frame. however, there are additional brackets on the A frame due to the automatic trans.

[stresssolutions]

Bummer.... because the manual I have downloaded is for the K, can't yet find an A.  As quick as it is, I can't imagine how fun a K or F or a "big" bike would be.

[05c50]

I'm in the middle of a 750a restoration right now.....have been able to find out some interesting info. There's more parts that interchange then you might think. If you go to www.cmsnl.com,you can plug in the part number and find out what else it might fit. For instance-the oil pan gasket is the same as a 1100 Shadow.....who knew??
 As far as the manual....go to www.helminc.com   they have repo of the original Honda factory manual for $36.00!! It only took 5 days to get it. It has been worth it's weight in gold already. If you need any specific info from the manual,I'd be glad to help.
  have fun.....Paul

[DarkRider]

Just wondering for curiousitys sake...couldnt one take the top end off of a K or F and use it on the A for more power?

[05c50]

Top end is similar,but the carbs are different.....smaller throttle bore,spaced closer together and they have throttle "kicker",but they are very much like 550k carbs. Helps to improve bottom end performance, might have a little too much hesitation with bigger carbs.



........Paul

[stresssolutions]

Thanks for the link, I ordered one.  I suppose if I had patience enough, I could scan the bugger and put it online for others enjoyment, but I don't.  Thanks to the guy that did post all those manuals.  WOW.

Tore into front brake today since it hangs up pretty bad.  Looks like the bleeder screw might be plugged. 

 Paul, Thanks again!  Mick

[05c50]

Careful with bleeder screw....they round off pretty easily. Once you get the caliper apart,there's only 2 rubber seals inside. The one in the cylinder is still available from Honda and it's not too expensive. But,take a close look at the piston, Be sure that it's completely smooth and there is no major pitting.
 I thought about scanning the manual also,but since it is a reprint,I didn't want any problems with copyright stuff. Besides it's pretty cheap and it's nice to have the whole book in the shop when you need it.
 Keep us posted on your progress.


.....Paul

[stresssolutions]

I ordered the piston seal from the local Honda dealer, it looks way too small, it looks as if it would fit entirely inside the old seal.  I have not yet opened it...

Part number 45108-300-003 matches the right part in the parts book for CB750-CB750K1-CB750P that I downloaded somewhere.  Can anyone verify if it is right or not?

Piston has only a couple small pits.  Bleeder screw unscrewed, and is not plugged.  I was thinking of putting anti-seize on it when I reassemble.

thanks

[05c50]

Yep, 45108-300-003 will fit some 750's,but not the 750a....it will fit the 400 Hondamatic though. I think the part you want is 45215-533-043.
  By the way,try not to get anti-seize on the seat of the bleeder.


.....Paul

[Dave Wyatt]

The top end of the A will swap with the other SOHC 750's.  There are a few running around with 836 kits in them!  As was mentioned, the only real difference is compression ratio, cam lift, carbs, and the transmission.  They do use engine oil to run the transmission, therefore the engine is a wet sump.  There is a Yahoo Hondamatic group with good info.  http://autos.groups.yahoo.com/group/hondamatic/

[OldSchool_IsCool]

How timely that this topic has bubbled to the top!  Pardon my thread theft, but I'm going to look at  '77 750A tonight!  In reading this thread, it sounds like it is more similar to my '77 550K than the typical 750. 

I don't think the 750A I'm going to look at is running.  I'll give it a good visual inspection (condition of the seat, tank, frame, bits and pieces) is the engine seized, does it have compression (good to know the ratio is only 7, I'm used to my 550K with 9).

Anything else specific to a Hondamatic I should pay close attention to?

[05c50]

Check the parking brake....yeah they have a parking brake, when I got mine, the brake was stuck on. It was rusted up tight. I was able to repair it,but the parts are hard to come by.


......Paul