Topic: 1973 CB750K3 - One Owner Barn Find - 5,310 miles - Final with Pics

[Johnie]

It deserves some new bling.   Heck, I'd offer to double your buying price....as is - you wouldn't even have to buy the pipes. 

I hear you green jeans, but you will have to hop in line.  Since I started this thread I have had quite a few generous offers. My plan was not to flip it, but restore it this winter. This will be a fun one.

[Old Scrambler]

Nice Score Johnny...............when you add the 341s we will have matching bikes!  That production is early and the shape of the fins on the front of the head matches your earlier bikes. That changed during the K3 run.  Could be 105 main jets.  Kinda slow around here but does well on Pikes Peak.

[dhall57]

It deserves some new bling.   Heck, I'd offer to double your buying price....as is - you wouldn't even have to buy the pipes. 

I hear you green jeans, but you will have to hop in line. Since I started this thread I have had quite a few generous offers. My plan was not to flip it, but restore it this winter. This will be a fun one.

Don't sell it!!

[Johnie]

Nice Score Johnny...............when you add the 341s we will have matching bikes!  That production is early and the shape of the fins on the front of the head matches your earlier bikes. That changed during the K3 run.  Could be 105 main jets.  Kinda slow around here but does well on Pikes Peak.

Dennis....the build date is 10/72.

[Old Scrambler]

Same as mine...........

[hoodellyhoo]

now either you or I need to buy an original K5 so we can line all our bikes up for a picture of all the original-styled cb750's K0-K6

[Johnie]

now either you or I need to buy an original K5 so we can line all our bikes up for a picture of all the original-styled cb750's K0-K6

That went through my mind. It would be a cool pic of all the early 750's.

[754]

Nice bike I think you and Dennis should compare serial numbers.
 Ran into a guy this simmer had a KO since new, serial # was 305 higher than one of my motors..

[Johnie]

Dennis...this K3 has the 110 mains. Success...I was able to break the oil filter bolt free today. Not as bad as some I have seen. What are you guys replacing these bolts with? I have an identical one from a parts bike I may use and should not have a problem knowing they do not need to be so tight. Here are a couple pics taken after giving it a wash.

[Old Scrambler]

Nice and clean..............better than mine!  Replacement oil-filter bolts are available with a 14mm head........otherwise just look for a clean stock unit.

My motor number is E 2210097

754 (Frank) had a Bucchus Olive Green bike but installed an 836-kit many years ago.

A lady in Fond du Lac gave her son a Green K3 with original pipes about 8 years ago..........I followed him to their service garage business but lost track since.

[Johnie]

My motor is 2210336 which was 239 bikes down the line from old scramblers K3.

[dhall57]

Johnie and Scrambler, never really thought about it much, but comparing vin#'s and eng#'s on other members bikes is really a good idea especially with your K3's having the same 10/72 build date. Just a little bit of history think about it you two, in October 39 years ago in Japan the K3's your now have in your garages here in the good USA came of the assembly line in Japan only a couple hundred bikes apart. And now both of these 750's are in Wisconsin and the owners are talking to each other over the internet on this forum about these two bikes all these years later. What are the odds of that happening. Things that make you go hmmm

dhall

[Johnie]

dhall...I never thought about it that way. You are correct, after 39 years who would figure this to happen. And without the internet we would never know.
Today I plan to get the old oil out of the K3 and put on a new filter and filter bolt. May pull the carbs too. The tank is very clean with no rust and no gas. The carbs did not fair so good. He left gas in them. I have some clean extra carbs here with 120 mains compared to the 110 mains in this set. I may put those 120 carbs on just to get this fired up before winter. I want to get oil into the motor and through the engine.

[dhall57]

Yeah Johnie get some clean fresh oil in her, that was one of the first things I did also on my KO when I got it back in May.

[Johnie]

Got the oil changed and put some in the top end through the valve adjuster caps. Also put a little in each spark plug port. Turned it over a bit to run that fresh oil around. Noted the oil had been changed as I see the oil filter washer next to the spring was gone as most of them are. Replaced that and plan to check compression this week. I would hope it is fine with only 5,310 miles on the bike, but I know weird things happen when they sit for long periods. Appears this was in a dry place during the storage.

[ekpent]

Hey Johnie. Out of curiosity today when I went for a ride I checked my numbers on a couple of 73's in the shop and took a few pics. My Bacchus Green is pretty far off from yours,build date of 1/73 and engine number 2222680.
   The Flake Orange 73 has a build date of 2/73 with an engine number 2239207.
  Guess I can't hang with you guys 
 PS-Still got your Gold K1's sister over here  ;
  Sounds like your close to firing that new one up if you haven,t already.  Enjoy it,sure its going to be fine.      Eric

[Johnie]

Great pics there Eric. Love looking at your collection! I did a compression check this AM and here are the numbers: #1 = 150. #2 started at 100, then after a bit went to 110, then after a bit went to 120. #3 = 150 and #4 = 160. These were done with a little oil in the cylinders and throttle wide open. That #2 was a weird one starting low and then increasing as I checked the others. Therefore, I am banking that there is a bit of a stuck ring that will free up once I get the bike running. I noted spark on 1&4 points, but no spark on 2&3 points. The carbs are so dirty I plan to remove them today and have at it. Here are a few more pics from today.

[Tews19]

Looks like it is coming along. Are those spark plugs in order from left to right 1-4? In the pic, the 2nd spark plug is missing the metal gasket. Could this cause the compression test to be off on the 2nd cylinder? Maybe the metal gasket is still on the head

[Johnie]

Good eyes there Tews...I did catch that before the compression check. That plug gasket might have rolled somewhere on the floor as it is not in the plug port. With #2 increasing so fast from 100 to 110 then 120 in a few short minutes, plus the fact the bike has 5,310 miles on it, I am keeping my fingers crossed continues to improve as this motor gets freed up.

[Johnie]

OK...another update. This afternoon I took off the carbs and these are the worst I have seen. All needle valves with the exception of one is froze. Have the bowls soaking now. The 110's and the 40's have small BB like globules of old gas on them. The gas that was still in the bowls must have been about 35 cents a gallon then. The air box is like new as is the OEM filter. The air box rubbers are a bit loose. Not sure if I should try to seal them up or buy some new ones. They seem to have shrunk a little. What a labor of love guys...

[smpls70]

Nice barn find Johnie , I have a 10/72 build date as well , just over the border here in MN. , to the basement I go to look at my engine #

[Johnie]

Great...let's see where your 10/72 ended up in the line-up on the way to the USA.

[zzpete]

  Nice score Johnie!! Truly a dusty jewel! I bet when you put the carbs back on that mutha will fire right up.

[Johnie]

Hey ZZ I am expecting this baby to fire right up...fingers crossed. Everything seems to be in order.

[zzpete]

When you get one running thats been sitting for a while, its an even better feeling than when you get it out of the barn!!!!