1981 CB750, 3000 original miles, $150 Bucks!!!!!

[750Kansan]

Hello,   A couple of weeks ago my wife and I were doing a little garge sale bargin hunting and we came upon this 1981 CB750K sitting towards the back of the driveway with a "make offer" sign on it.  I took a closer look.  Turns out this guy is the original owner and had put only 3000 miles on it and then parked it around 1988!!  It has sat covered in the garge ever since!  My wife asked what the asking price was and the owner says the best offer so far was 100 bucks and that I could have it for anything over that!  I quickly offered $150! So, I now have this awesome find in my garage and I'm going through it to make it road ready.  Here are some questions for anyone that could help.

1. The original mufflers are rusted out but the headers are like new.  I need some guidance on what to replace the mufflers with and where to get them. It originally had the 4 into 4 setup.

2. There is some very minor garage rash here and there but overall this bike looks brand new! Any guesses on what it is truley worth?

3. Any thoughts on Amsoil?

4. Any thoughts on pre-lubricating the cylinders be for the first start up?  

Any and all comments welcome.  Thanks.

Chad

[Rod_Knockin]

Ok, to start with we all hate you !  $150

With that out of the way.
1) I hear oldbikebarn.com has pipes also z1enterprises.com
2)running perfect shape I say $1500
3) not me
4) I hear that trans fluid works well. pull the plugs and fill up the cylinders. Let it sit a wile and then hand crank the bike over to get the lube back out. Kinda messy. Be careful rust on the cylinder walls will break rings. Dont apply allot of pressure. Should be smooth and easy with the plugs out.
other things:
change the oil before starting it but after you do the cylinder lube trick.
before you start it crank it on the starter with the kill switch off. Even better with the plugs out. Crank untill the oil pressure light goes off on the guages.
Clean and rinse the tank.
I would venture to say based on about 1/2 of the posts here "rebuild the carbs"
lube the chain. Replace tires
Ive also found that when a bike has been sitting that long the clutch plates may be stuck together. Be careful when putting it in gear the first time.

[gonebiking-2]

The four into four exhaust pipes were badly made by Honda in the first place. My first set only lasted two years. Then went to custom stainless steel ( 4 into 4 ) two years later the stainless steel pipes and the header pipes were not comptable and some form of corrosion set in. Off came the stainless steel ( badly made any way ) and on went a new four into four system and that was 22 years ago. Now thay are totally knackered. I have ordered four new exact replicas made by mivv in Italy - better quality materials used . The URL for the exhaust system is
www.mivv.com   Do have a look at their webite as they offer good replacement pipes ( no headers ) at a reasonble price.

[gonebiking-2]

I forgot to mention about the clutch. As stated in the other post, the clutch plates might be stuck. This happened to me after my 1982 CB stood for several months. Wha I did was to sit the bike on the main stand ( that lifts the rear wheel off the ground ) start the engine with the 1st gear engaged, let the motor warm up until it reaches what you would consider to be normal running temp and the engine oil is nice and hot. Bring the revs up to about 3000 RPM, pull the clutch lever in as if disengaing the clutch. If the rear wheel starts to slow down, then you are fortunate that the clutch has disengaged. If not, still run the motor at 3000RPM , hold the clutch lever in and jam your right foot hard on the brake pedal.That will break the seal thats binding the clutch together.  Result -  Instant free clutch !! Has worked for me every time the bike has stood for any length of time.

[750Kansan]

Thanks Mathew,  no offense taken.  z1enterprises has a bunch of good stuff but unfortunately no muffler replacements. Oldbikebarn does have some possibilities. I did find a distributor in Texas for MIVV for OEM replacement silencers for $700  

I might try the tranny fluid trick. Sounds plausible.
I am curious about the Amsoil comment.  I have never used it but those I have talked to that use it swear by it. Its exspensive so if I can get the same results with something else I would be open to that.

Believe it or not the tires look brand new for being 27 years old. I took a nail and poked around all over the tires and the rubber appears to be soft.  I plan to take it easy for awhile to see how they wear. Most likely they will be replaced.

I will post some pics when I get her all cleaned up and ready to the road.  Thanks again for the advice.

Chad

[Rod_Knockin]

not me just meant I have no experience with it. I used royal purple as Its the same oil I use in the Oldsmobile and I had enough for the oil change left over.

[TS750c]

try denniskirk.com thats where i got my Mac 4 into 1 exhaust

[blackhawkrider]

Nice find, the tires may look new but if they are old the will crack severly with only a little use I would check the date stamp if you can find it and replace the tires if they are more then 7 yrs old or so. Also Jardine makes a classic style exhaust for the cb750 http://www.chaparral-racing.com/Chaparral/dept.asp?dept%5Fid=4248&gift=False&0=assets%2Fhtml%2Fd%5Fstreet%2Easp%2CnavId%3Dd%5Fstreet%2A0%26menu%5Fid%3D%26Tree%3D%2CStreet&1=dept%2Easp%2Cdept%5Fid%3D1641%26menu%5Fid%3D%26Tree%3D0%2CStreet%20Exhaust&2=dept%2Easp%2Cdept%5Fid%3D4251%26menu%5Fid%3D%26Tree%3D1%2CJardine%20Exhaust&3=dept%2Easp%2Cdept%5Fid%3D4297%26menu%5Fid%3D%26Tree%3D2%2CJardine%20Slip%2DOn%20Mufflers&mscssid=00ECB79D7290D400E8C4A7CF66813E42 sorry for long link

[liljohnnie69-2]

Hi Chad,
 1.I would round file the 4 into 4 in favor of a 4 into 1 due to better scavenging.
 2.With the price of gas as it is $1500.00 would be in the ballpark.
 3.Amsoil makes a fantastic product,albeit expensive,i've used it in my cr250 and only paying $150 gives you a little room to play with now doesn't it?
 4.Prelubing is prudent,you could also find a mechanic with a good borescope to have a look before you try anything!
 Better expect to replace fork seals too,it's cheap insurance against coating your front brake with fork oil.
Remember,if your in a car and a tire blows out you pull over and change it.If your bike tire blows out it doesn't matter if you put on clean underwear or not your attending nurse is going to be cleaning you up.Change the tires!

    Ride safe
   liljohnnie69

[750Kansan]

Hello and thanks for the info!  The bike is running now but not perfect.  How likely is it that a valve shim change would be needed?  Also I think I will re-check timing, new plugs and then synch the carbs.  That should cover about everything.  I agree on the tires. Thanks again.

Chad

[liljohnnie69-2]

At 3000 miles i don't think the valves would need any attention unless the bike is running bad or popping out the exhaust.I think your right on with the new plugs but ride it after you change something just to make sure your headed in the right direction.As far as checking the timing,if you haven't messed with the base engine or the pickups that should be good.
The carb synch,unless you or someone you know has some idea of how to do it,you can do more harm than good unless your going to take it somewhere and pay someone and again you bought it right and have a little wiggle room there.

 BTW i am jealous,$150 bucks indeed!
        liljohnnie69

[750Kansan]

Sounds good.  I do have a retired bike mechanic that does a good job with synchronization.  Yes! Eveytime I look at this bike I still can't believe a paid that little. Take care.

Chad

[barnstormer44]

Hey CHAD
On the muffler thing.  I just finished resorecting a 77 CB 750-A, it has,, NON stock,, 2 in 1'2 on each side.  Kinda loud, wish I had the stock ones.    Not sure how handy you are but I went down to the local Harley shop and got some brand new never used take off mufflers for free,  (as lots of Harley guys take off the new ones and put louder ones on), and fit them to my wifes 440 Kawasaki.  Had to make some mounts but not a big deal.  Sounds good too.  

Not sure on the value most likely 1500 in good shape maybe more for very good.  My need to find out the value of my 750-A as they  only made them for 2 years I think and not many suto tranny's out there to boot.  

I am a Casterol Sentec man but I run it in all my rigs.  

You might want to pre lub the cylinders but be aware that you may foul the plugs for a bit, and have to take them out and clean them a few times before it runs.  Kroil in good or Marvel Mistery oil.  If there is a lots of rust on the bike it may have rusted the bore but it kinda depends on the location of the bike.  I live in the desert so around here if it has been kept inside, it good.  The coast is another thing.   I have done reserected a few bikes and there is a lots of things that I have found and fixed.  You should go through every section of the bike and start from one end to the other and make sure all systems are go before you get all jacked up and go for a ride.  The brake fluid in the front brake had turned to jelly and plugged the line.  Had to take a wire to ger er done.  Lots of thing, use your head and take your time.  Should be books out there for the first time guys.  

[gonebiking-2]

I doubt that you would need to check the shims on the tappets as after only 3000 miles- thats hardly run in. As the timing is electronic and no ignition points to worry about you shoud not have to play around with it. If you do,  get someone with a strobe timing light and check in the hand book where the timing should be.

[750Kansan]

Great advice, thank you.  I have installed an oem exhaust from a 79 750 that looks real good. I found it on Ebay. I soaked the cylinders with transmission oil for about a week and I did foul the plugs several times during the first attempts to start.  She is running now although not perfect..  Next steps, new spark plugs, and carb synch.  Great idea about the Harley mufflers, I will look into that for future replacements.
Thanks again and best of luck on your 77.
Chad

[750Kansan]

Hello,  Thats good to hear about the valve shims.  I have read up on the process and it sounds very time consuming.  I need to install new spark plugs, install new exhaust gaskets and synch up the carbs yet.  I have been up and down the street with the bike and its actually running very well with the exception of it being a little " bogy" on excelleration and a couple of exhaust leaks.  Thanks very much for your input.

Chad

[barnstormer44]

Sounds like you have a good start.  Many years ago I bought a gallon of Chem Dip from a auto parts store.  It is used to soak your carbs and it really works.  I got tired of paying the bike and lawn mower shops to do it for me and they use the same stuff.  I think my can is 20 years old and used it the other day, still good.  It eats anything rubber so make sure you only dip metal parts.  I took the carbs off the bike but didn't sepparat them from the rail that marries them together.  took out the jets and soaked them and the bowles out and blew out all the galleries and jets and bought new bowl gaskets.  Also make sure that the float needle valve, dose not have a groove aroung the seating area.  If so replace.  I did make some big head aches for my self as I only put the main jets back in place and forgot to tight them and when I was trying to run the bike it was real bad.  After pullin out the remaining hair I have I took them back apart and found the mistake.   I would adjust the valves, check timming and points if it has em.  Make sure you read the vavle timming carefully as it is wierd.  I messed up thinking that 1&4 fired together, and 2&3 did the same, not so.  You have to do 1 and then rotate the crank 180 then do 4, same thing with 2&3.  I was tring to do 1&4 with out rotateing the crank.  I ended up do the valves about 4 times.   I hate reading directions.  Need to though.  If you have rust in the tank, I would definatly get a POR 15 tank kit and coat the tank.  MAKE SURE YOU PULL OUT THE SCREEN AFTER YOU TAKE OFF THE PET COCK, OR IT WILL GET RUINED AND COATED FOR EVER.  I DIDN'T KNOW IT CAME OUT AND HAD TO TRASH IT AND PUT AN INLINE FILTER IN.  FIrst time I took the bike for a spin, it was starveing for gas with pet cock in the ON pos, and would only run on RESERVE, (screen was sealed )
I may get a new one but I think the inline filter will work fine.  Hope this all helps drop me a line or you could call  if you get stuck.  

[750Kansan]

Yep, I have the same "Dip" for my parts.  The carbs have been gone through and thankfully the previous (original) owner shut the fuel off prior to storing the bike so the carbs really were not too bad. I still soaked everthing though. I did have rust in the tank so it has been cleaned, prepped and sealed with Kreem. I lucked out and found the petcock screen prior to sealing so it survived. I also have an inline filter for extra protection.  I will try to post som pics today.  Thanks

Chad

[blurat]

I am thrilled to the bone. I beat that one by 150 bucks. I have a Victory and was standing around at work talking to a friend and my son when another character walked towards us. We were going to split up and leave but he joined in the conversation. One guy asks him"you still got that honda?". He says yes and my son asks what he wants for it. Said come pick it up, no charge. Im told it is in show condition, fairing, bags but he cant get it started. O well, guess my son got me into another project.
 All the above feedback has already helped me imensly.
 Thanks,
 blurat

[750Kansan]

Blurat, Congrats on the score! Is it a CB750?  I assume that it is.  Luv to see some pics.  Best of luck as your bring her back to life.

Chad