Topic: 1976 CB750 Cafe Racer Project

[dummkauf]

This is the start of my thread for my cafe racer project.  This will be my first time building/restoring a bike so this is a learning experience as well as my new project.  I purchased my 1976 CB750 on Craigslist for $475.

I have a feeling I will be asking a lot of questions on these forums so I thought that I would start a project thread to keep everyone who may, or already have, helped me updated with the latest progress.  I will get pics uploaded on here to cover the general progress of the bike, if anyone wants more detailed pics check out the "cafe racer project" section under motorcycles at http://www.thesandmann.com  this is a personal site i have recently put up to track my project and almost all of the pics I've taken throught this project are getting posted there.

I will get some pics uploaded to the forum here shortly

[dummkauf]

This is what she looked like the day she got dropped off in my garage.

[dummkauf]

found this kind of interesting......haven't tried calling the number yet though 

[dummkauf]

Got the carbs and the airbox off...

[dummkauf]

Got this guy out and the exhaust is now finally removed!



Had to rotozip a groove into what was left and then pound it out with an impact driver and a flat head bit.  The impact driver rounded it out further but atleast loosened the screw enough that I could get it out.  Thanks for all the suggestions on getting this out to everyone who offered advice.

[dummkauf]

Finally got the engine out of the frame.  Required several hours of cussing, the assistance of my wonderful girlfriend(believe it or not!), a 2 ton jack, a piece of wood, and a motor cycle jack.

The engine is currently strapped to my motorcycle lift/jack and will remain there until I get a chance to make the brackets to bolt it to my engine stand.  Found some 2" angle iron about 3' long at menards, and picked up some metal cutting blades as well.  I am planning on chopping it down, and drilling some holes which will eventually provide me with the needed brackets to mount the engine on the stand(an idea which came from this forum)


Here she sits engineless    hopefully not for long though.....I'm not touching the frame or any other body work until I have the motor rebuilt and ready to go.  So this guy is going to get ripped apart and stored in the corner for a while.

[Hush]

Original bike was 90% there so you have a good start on this project.
Love the piccies, keep em coming.

[dummkauf]

Got the engine onto the engine stand!

Hooked the engine up to the stand and then had a friend help me pick it up

[dummkauf]

Got the head off!



This is looking a bit sooty



The one piston that wasn't completely black

[martino1972]

looks like that one piston isnt working along with the rest..

[dummkauf]

Just got the case split.




I did notice something interesting about my connecting rods and I am not sure whether or not I should be concerned of if this is normal.  I noticed that each connecting rod has a number written on it across the joint that holds it onto the crankshaft.  From left to right the numbers read 3,2,3,3  The other side of the connecting rod says "F" on all 4 of them.  Does anyone know what is up with the 2 on the second rod?  It looks identical to the other 3 so I'm just curious as to why the one rod is labeled differntly than the rest?

[scunny]

the letter is the conrod weight code, all should be the same
the number is the big end journal size code, I "thought" they should be the same but maybe not due to different bearing thicknesses

[dummkauf]

Good to know.  I'll have to check the bearing thickness on that one compared to the other 3 when I get home.

If it does have different bearings will that affect anything or does it not make any difference so long as the connecting rod matches the bearing?

[bunghole]

the letter is the conrod weight code, all should be the same
the number is the big end journal size code, I "thought" they should be the same but maybe not due to different bearing thicknesses

I think it is OK if they're different, I just thought it was important to have 1 and 4 match and 2 and 3 match.  That's how mine are...I think...

[rbmgf7]

mine's 3,3,2,2 and have K on the other side but is from an F

[Sully_PA]

Good luck with the build. Be watchin' your engine rebuild

[dummkauf]

Thanks, I'll need it


I'll likely be on the forum with lots of questions as the engine goes back together

[dummkauf]

the letter is the conrod weight code, all should be the same
the number is the big end journal size code, I "thought" they should be the same but maybe not due to different bearing thicknesses

Well according to my micrometer there is a 0.02mm difference between the two.  I'm guessing that's not too big of a deal and since I doubt I got the micrometer centered perfrectly in the ring on both of them either way.

[rachet]

I'm excited to see your progress, keep up the good work!

Rachet~

[Tretnine]

keep it up man! I just bought this yellow machine a month ago and I love to see all these projects. I'm not sure which way to go with it, but they inspire!

[dummkauf]

Attempt number one at buffing and polishing 

I started out doing just a section of the upper case and I am going to have to redo the part I've already done, but I wanted to get an idea of how this would turn out.  I started out using a dremel with a very soft grinding disc and used it to smooth out some of the casting flaws.  Then I wet sanded the case starting with a 280 grit sandpaper and worked my way up to 1500 grit.  Granted after I was done with the 280 I probably moved up to finer sand paper a bit faster than I should have.  Then I used a sewn buffing wheel on my drill with the red buffing stick, followed by a loose buffing wheel with the white buffing stick.  It's nice and shiny and I want it shined up a bit more, but overall I think this will work for the cases.  It's not my chrome finish but I think I it will do 

Since this is the first time I have ever attempted to sand and buff aluminum ever, I think I did a pretty good job(but still have some room for improvement)

Also, does anyone have any tips for sanding in the tight little corners and crevices of the cases?

[comp]

looking good 

[dummkauf]

Haven't posted in a while, but I figured I should add an update on here:

- Gave up on polishing the cases.  This seemed like a good idea when I started but looking at all the little nooks and crannies and castin flaws that would need to get buffed out I decided I want to get going with this project and have decided to just send the cases in to a machine shop for a hot tank and bead blasting.
- I found a machine shop to do the work but I haven't gotten around to dropping the pieces off yet.  I was just going to drop off the cases, and cylinders originally, but I think I'm going to finish dismantling the head so I can take that in at the same time.
- I've started rebuilding the carbs.  I've got them dismantled and all the parts cleaned up and am currently in the process of sanding and polishing the bowls, and a few other small parts to shine them up.  Had to order a new set of float bowl gaskets, and I'll likely need to rejet once I get the engine back together but I'm going to wait until the engine is running to start on that.

Guess which bowl is done

[dummkauf]

Ok, I've finally learned that I can't get by with a buffer wheel attached to my cordless drill because it just wasn't getting my parts shiny enough.  So I spluged at good Ol harbor freight for a buffer and a stand, ran me about $80 for both.

Here's the new buffer


And my pretty float bowls


Here's a before and after



Even buffed up the clips



Something tells me this buffer is gonna come in handy through out the rest of this project