Topic: How to tell what year of bike?

[Kris]

As some of you know Im working on my father inlaws bike that he bought new in the 70s.  Its been froze up since then.  I got it unstuck and am in the process of rebuilding it.  I want to say that its a 1974. Form memory.  I dont want to ask him outright if I dont have to cause I want it to be a suprise.  I found this number printed on the engine case.  Does it indicate what year the bike is?

CB750E 2239407

Parts are to expensive to order the wrong ones.  Thx

[david 750f]

Looks like a 1973.
http://www.sohc4.net/cb750k-serial-numbers/

[754]

We can tell you more from a pic. Serial number wont help if forks and motor are swapped...things like that..

[Kris]

Looks like a 1973.
http://www.sohc4.net/cb750k-serial-numbers/

Thanks man, good info. 

[bryanj]

Frame number is a better idea for year rather than engine, is stamped into headstock on L/H side of headstock and should be an I.D. plate on R/H side giving year and month of original build

[ekpent]

Always a good idea to check both the frame and engine number to see what you have going on. Sounds like Pops was the original owner eh, I would like to see a pic of the bike also, what color is it if still stock paint.1973 would be green, orange or brown.  That had fairly low miles didn't it from another thread ?

[Kris]

Always a good idea to check both the frame and engine number to see what you have going on. Sounds like Pops was the original owner eh, I would like to see a pic of the bike also, what color is it if still stock paint.1973 would be green, orange or brown.  That had fairly low miles didn't it from another thread ?

Yes he is the original owner.  The bike is a dark green.  Once I removed the engine last year he took the bike home with him to free up room in my garage.  So I'm gonna at some point have to go and get it without him knowing.  Once I get it back i will post some pics for you guys.  I want to say the miles are around 3k ish.

[ekpent]

Sounds like the color Bacchus Olive they used that year,and Oh by the way that was the fastest color they made         Member Johnie has a real nice one also.

[754]

Saw the motor pic, its early 73. ...or older
 Dennis ..old Scrambler.. has an early  73 CBO with the same head.

[Old Scrambler]

754 sent me here..............and Yes, my original K3 is motor number 2210097 with the same 'tins' color..........also known as the fastest color........AFTER you change the 105 jets to 117s or 120s and install a K&N air-filter.  Regarding motor parts...........many are available on this forum. If you need new pistons, I have a set of 2nd or 3rd over (can't remember) just like the 1st-over units I installed several years ago. If you must bore, be sure to have pistons in hand and send to the machinist for the best fit. If you do not have to bore, a good set of used pistons will work with new rings, pins and clips. At that low of mileage, I doubt if the valves need anything, as long as serious rust is not apparent. If the motor has been stuck for a lot of years, one or more sets of valve-springs are likely to have lost their full extended tension. Again, good used units (within shop-manual tolerances) will work.

If you go for used pistons, I recommend a set from an F0, F1, K7 or K8 motor.  They have a slight dome for a compression change from 9 to 1 up to 9.2 - 1.  It may be a good time to replace the oil-pump check-valve.........and of course you will re-assemble with new pucks, oil seals, and gaskets. Please remember to seal the inner 4 cam-tower studs on the exhaust side to prevent a 'weeping' oil leak.

Its a great effort to build this surprise-gift. You will get a lot of help from this board.

[Kris]

Awesome thanks guys,  thanks for the tips as well.  Something's in there I hadnt thought of. I'm taking the head to a machinest  tommorrow to see if it will be OK with just a hone.

The pucks are the black pieces in the head right?

Will do on the can tower, thx.

Going now to add to the whiteboard in the garage.

[Kris]

I think one of the hardest parts is going to get the fork lined back up on the shaft with the clutch assy while mating the two halves of the engine case.

[Old Scrambler]

Yes to the Pucks in the HEAD...............take the barrels (cylinder) to the machinest. Apply very thin amounts of RTV to the pucks and other gaskets.  Also suggest reading one or more of the motor build threads on this site.  The HONDA shop manual is a must. 

[Kris]

I don't mean to be the guy that asks everyone to do the legwork. But I've used the search button for rebuild, engine away etc and looked in the section with important topics for just reading and can't seem to find a extensive rebuild thread. Did u have one in mind? I understand if u don't have the time to look, and have been a help already. I will continue to look. Thx

[jerry h]

Hi,
You may be doing this all ready,  but the more useful search here is the "Google Custom Search" field in the upper left, below the orange HOME button in the tool bar - not the "Search" button at the top right.

Don't think there is 1 engine rebuild link to point to, but tons of useful bits to learn stopping in to check out other people's builds in the Project section. Usually I just use the Google custom search on any topic at hand, and volumes will come back at you.

If I recall, you have the Hondaman book, that's about as good as any, to help walk you through your first SOHC engine.

[Johnie]

Good point Jerry...go to the top of this page and find the "member" tab. Go to the H area and find Hondaman. Send him a message from that page about his CB750 book. He is considered one of the top mechanics on these vintage bikes and he wrote a book about the engine, rebuilding, brakes, suspension, etc. Something you will want and use for your project. It will answer a lot of your questions. Sounds like your bike matches the K3 pic below. If the pic is to small click it. Good luck and let us know how you come out.

[ekpent]

Hondaman has a thread going on about the rebuild of his trusty high mileage 72 engine that may be worth a little peek for a few pointers.  http://forums.sohc4.net/index.php?topic=122379.0

[Kris]

Classy guys here!  Thx.  Soon as i get a break from work I'll check it out. 

[Stev-o]

Classy guys here!   

What, classy? Who you insulting?!!

[Johnie]

 

[Kris]

Ha!  hey wuick question.  Ordering rings this morning.  Is my bike a k or f series.  Im pretty sure that its a k series but just want to make sure.  Thanks

[ekpent]

They did not make an F in 1973 so yours would be a K3.

[Kris]

Thx, not having the vin number is slowing things down.