1983 CB750 DOHC Build

[ljonny18]

Hi all I am new to this forum. I was searching the internet for CB750 builds to get some inspiration, ideas and motivation to get me going again on my current project :)  I will start posting my 1983 CB750 build on this thread. I have already done quite a bit, so will have to play catch up for the first few posts :)

[ljonny18]

I picked up my new (and first) project bike: A 1983 Honda CB 750 RC 04 earlier this year:

I got the bike cheap in an Ebay Auction although it is in a lot worse condition than I originally thought and is currently a non starter.

I have no current fixed plans for the bike so any inputs are welcome !!! The first step is to try and get the motor started to see what I have, and then strip it down to its bare essentials :)

As mentioned, this is my first project and I am a bit of a novice but looking forward to seeing what I can do with the bike !!!

I will update this forum as I make progress with the bike !!!

Attached is the picture taken from the Ebay Ad:

[ljonny18]

I got the bike home and into the garage. Here are a couple more pics before I got to work on it:

[Johnnylevi]

Do you know how long the bike was sitting for?

[shinyribs]

Welcome to the forum! Interested in seeing what you do here. Good luck and have fun!

[Hoosier Daddy]

Yea, welcome and bring it on!
I'd have snagged that one up myself if it was a decent price.
Take your time, take lots of photos during disassembly so you can refer to them when you go back together. Baggies and a sharpie to "Bag-n-tag" all the small parts and fasteners are a first timers best tools.

[ljonny18]

Johnnylevi wrote

Do you know how long the bike was sitting for?

Yeah... it was sitting for over a year :S

[ljonny18]

The bike had no power :( at first I thought it had a flat battery until further investigation proved it had no battery at all :

[ljonny18]

The new battery arrived, so I filled it with acid and let it charge for a few hours before fitting it:





After checking the oil and giving it some fresh petrol, it eventually started :)



OK, so its a runner (sort of)... After finally getting the correct battery sorted and fitted, it eventually started :)

However, there was a not too healthy knocking noise from the engine  The engine is coming out in anycase biut if anyone has an idea re what it is likely to be im interested. It sounds like a "mechanical" knock so im guessing its going to something like primary chain rattling or crankshaft bearings ?

[ljonny18]

Today I managed to find a bit of time and I started to prepare the engine for removal.
Some progress pics:

Managed to clear a bit of space (althpugh not much :( I have too much junk) so I can work arounf the bike a bit easier:





The carb rubbers(both sides) were that old and worn they were solid and had now flex in them at all :( therefore I had to remove / move back the Air box and housing to give me more room to maneuver the carbs and have any chance of getting them out. To enable me to move the air box housing back I had to firstly remove the Battery casing:





Battery casing out:

[ljonny18]

Onto the Carburetors:







Removing the Throttle / Choke cables:



and out

[ljonny18]

Time to remove the scratty old Exhaust:





Tacho cable:





HT leads:



Front sprocket:

[ljonny18]

The motor is now pretty much ready for removal (i hope) its all free of components and cables connecting it to the rast of the bike. I just need to drain the engine oil and somehow get this nut undone:



I cant for the life of me undo it - its solid... I will try and get a nice long(er) breaker bar and give it another shot.

[masiste]

 Nice job.

   Taking it appart is the way to go. It does not lookmbad at all, just dried up and rusty but new life will come in.

   That noise could be valve train, springs or valves sticking.  No worries, you need give it a valve job to refresh it anyways.

    BTW. This is what you could do with your bike, just ideas.













   

[Piute]

   

Hoosier Daddy wrote

Yea, welcome and bring it on!
I'd have snagged that one up myself if it was a decent price.
Take your time, take lots of photos during disassembly so you can refer to them when you go back together. Baggies and a sharpie to "Bag-n-tag" all the small parts and fasteners are a first timers best tools.

       
,Also tag 1to1 or red to red ,every trick to keep things in mind straight,pictures are my fave.,I HOPEYa have that bolt sokeing in penatrating oil overnight,It will come,Easy on it

[Hoosier Daddy]

I must say, that was the flattest battery I have EVER seen!
 

Don't sweat the knocking noise just yet until you get it out and apart and start really checking things.
She looks like someone spent some time on her in the past so you may be pleasently surprised.

Here is some inspiration for ya...

Linky to Google Images

[ljonny18]

jaimesix wrote

Nice job.

   Taking it appart is the way to go. It does not lookmbad at all, just dried up and rusty but new life will come in.

   That noise could be valve train, springs or valves sticking.  No worries, you need give it a valve job to refresh it anyways.

    BTW. This is what you could do with your bike, just ideas.

... [show rest of quote]

It will be getting a valve job for sure.. the knocking noise was coming from a lot lower down (in the bottom end). Im (only) guessing but I think it could be the primary chain knocking... will have to investigate further :S

The bikes look good !!! I really like (and have always) liked the silver / blue colour scheme. The read racer also looks good too - thanks !!! All ideas are welcome and appreciated :)

I will pb get hated for saying this, but the later F model CB's (like mine) are (in my opinion) the most ugly of the lot :S especially the tank... I have in the back of my head to try and do something using the newer DOCH motor but bringing back some older styling, maybe doing something different with the tank etc.... Anyway, early days, and im sure the F model will grow on me more over time :)

[ljonny18]

Piute wrote

Hoosier Daddy wrote

Yea, welcome and bring it on!
I'd have snagged that one up myself if it was a decent price.
Take your time, take lots of photos during disassembly so you can refer to them when you go back together. Baggies and a sharpie to "Bag-n-tag" all the small parts and fasteners are a first timers best tools.

       
,Also tag 1to1 or red to red ,every trick to keep things in mind straight,pictures are my fave.,I HOPEYa have that bolt sokeing in penatrating oil overnight,It will come,Easy on it

Dont worry there will be a lot off pics on the way - and yes, a lot of penetrating oil, soaking, and a bit of force got it off :)

[ljonny18]

Hoosier Daddy wrote

I must say, that was the flattest battery I have EVER seen!
 

Don't sweat the knocking noise just yet until you get it out and apart and start really checking things.
She looks like someone spent some time on her in the past so you may be pleasently surprised.

Here is some inspiration for ya...

Linky to Google Images

Thanks for the link !!! I spent about 2 hours looking at pictures :) now I have a lot of (if not too many) ideas spinning around in my head :D

Thats te plan re the knocking noise... take the motor apart and see whats what ... Im glad someone thinks its was once looked after, I think it is in a right old sate and has bee abbused most of its life haha :)

[ljonny18]

After another day spent in the garage I managed to get some more progress done (i cant wait for the clocks to change back again and the weather to get better, so I can get some hours in after work during the week).

My mate T came round to help me get the motor out, but first we had to finish a few bits off to prepare the motor for removal:

mmmmm not the best looking oil I have seen...



This is the bolt I have been having a few issues with re getting it off:



We eventually got it off (after some effort and an additional trip to the DIY store)



Jack in place to take some of the engine weight:



Started to remove the engine bolts:









And frame mountain bracket bolts:





Ready to be lifted out:









Out :)





Cheers T :)