Topic: '78 CB750F - Orange-ish Black

[Davidov]

I got this CB750 F3 at a good price, with title, and running to some extent.   
The orange turned me off at first, but I think with the right accents it will look mean.
This first picture is from the ad.

I want to get everything operational and reliable before getting out on the road. Carbs have come off, cleaned, set float levels, and all around tune-up.

I don't really see this bike becoming a major custom/chopped up build. I want to update some things, and make it look like a meaner version of the stock bike.
Some lower bars, maybe shorten up the stock SuperSport seat, add some badging, etc...

I would love some feedback, thanks!

[BeSeeingYou]

Looks like it is in decent shape and and good basis for your project.  They did come in orange in 75 so while not correct for your year it's still in the "family".  

[Davidov]

Making progress, trying to get it road ready!
New bars installed, new headlight brackets, lowered the gauges.
New RK 630 chain installed, 15 tooth sprocket on the front (+1), new stock 43 tooth rear sprocket.
Carbs off, float levels set, thoroughly cleaned, #38 jets installed, synched carbs.

Along with loads of maintenance: oil change, valve adjustment, etc...

[kap384@telus.net]

I'm actually surprised at how many 'F's have been popping up over the last few months.  Great to see another one!

[Davidov]

I'm ditching a good deal of chrome that you can see in the original photo.
The orange paint was a bit of an eyesore at first, but it's a very quality automotive paint job. Not some rattle can driveway job(which I've done before  )
I may end up sticking with the Comstar wheels, for originality sake. They don't really go with the classic look of most 60s-70s bikes, but they work.

[Graydude]

Welcome to my world!  Check out my 78 F3 project.  I'll be starting the re assembly of the motor this weekend to put on my freshly finished powdercoated frame.  I hope the fun begins now as not so much up to now.

[brandEn]

Got to love an orange F3 
 

[Davidov]

Got to love an orange F3 

Indeed! I love the look of your 750F. I want to put some sort of black stripe/logo on the sides, similar to your scheme.

[Davidov]

Here is some recent work. I finally got the title tranferred and a new license plate, so it's street legal!
I took off the rear chrome grab handle/turn signal mount/license plate mount. It was just took big and chrome for my taste. I mounted the tail light to the rear cowl with some custom brackets. This will also hold the license plate, so it's illuminated at night. (no cops please  )

I took some thickness out of the foam, and smoothed out the shape. I need to redo it though, due to some wrinkles.

I am suprised how much a few cosmetic touch ups made the 750F look so much meaner.
Finally, and most importantly. It SCREAMS. Thanks to some tuning help from Gearheadgreg.

The 15 tooth sprocket takes a little away from the low end, but 5K RPM and up compensates for it. Now it just needs some mileage added on!

[Davidov]

The tail light setup you can see in the previous posts didn't work out. The stock tail light was so heavy it cracked the cowl, and fell off on the highway. 
So I had to reinvent. As most of you know, one modification usually turns into 20. I got a new LED tail lamp assembly with integrated turn signals.
Here are pictures from chopping the seat.
I ended up removing about 2 inches in length. I removed material from the middle, that way I kept the stock "F" tail cowl. It's riveted and welded for extra durability.
I will post some finalized pictures later.

[lucky]

If you had put NEW float needles in it ,it may not have needed ANY float level adjustment. The only way the floats can change adjustment IS when the float needle gets crushed down.

[Davidov]

Only the slow jets were replaced.

[Davidov]

Project status time. My 750F has been under regular use for the past few years. Now the oil leaks have become more than just a slight "sweat". The cylinder compression was a little less than desired, so time for a rebuild!


Engine removed, top end disassembled.

Taking time to measure and inspect per the Service Manual and HondaMan's CB750 book.

Looks like tweedle-dumb installed 2 of the valve springs wrong side down 

[Davidov]

No real damage so far.
The exhaust valve guides had excessive clearance. I do mean excessive, spec is .08mm, I had over .50mm.

The only real impending failure was one of the rocker shaft hold down bolts. Which can be deleted, which I've learned from HondaMan's book.

http://forums.sohc4.net/index.php?topic=138787.msg1568587#msg1568587

Fortunate that I can discard them, and that this one didn't wiggle out at highway speeds!

[Davidov]

Before and after piston clean up. Removed all carbon and oil buildup. Cleaned all ring lands.

[flybox1]

nice work so far.
be sure and read thru this before you start working on the top end 

http://forums.sohc4.net/index.php?topic=107040.0

[Davidov]

Yes, I've looked it over several times.
The black-case F engine is becoming more understandable now.   

Haven't bought parts yet, but now that everything is nearly sorted out...I'll most likely be going with some brand of HD cylinder studs.

[Davidov]

Ok, can I get some input?

Intake valve #4 is a different design. I recall something like this being the earlier design?
I should have a matching set of valves, right?

Second picture is the Intake rocker shaft of cylinders 1 and 2.
It's on the outboard side (left side). The oblong rough spot.

[Davidov]

HD APE cylinder studs are on their way from Dynoman, so I took the OEM studs out today.

Only 1 gave me a hard time, so I turned it into an integrated tool.
2 studs were loose, as in loose enough to remove by hand 

[Davidov]

A bit out of chronological order, but here's a cool picture of the machine after a camping trip May 2013.

[Davidov]

APE studs are installed.
Torqued to 8ft-lbs/11Nm w/ a light application of Loctite.

I used the method from Branden and MRieck; mocking up the cylinder and head to snug up the cylinder bolts. My understanding is that this puts a little tension on the studs and makes them align properly while the Loctite cures.

More parts en route!

[Davidov]

Cylinder installed. Decided to use viton o-rings on the rear oil feed holes, and copper coated the base gasket.

Picked the head up from the machine shop, and he did a great job.
Bronze guides installed.
3-angle valve job complete. He said the 45* was almost worn away due to the sloppy guides.
I did some mild work on the intake ports to pretty much just blend in the factory port work.

8/28/2014- Cylinder head installed!
Viton o-rings on the rear feed ports here too, copper coated the Vesrah head gasket. Added some very light permatex non-hardending sealer around the cam chain tunnel.

[Davidov]

Engine finsihed up.
Used a thin layer of ThreeBond on the valve cover with the Vesrah gasket.
Replaced all the cross point 6mm bolts with allen/socket head bolts in black finish.

The joker that had this engine apart last left out the two bolts under the breather cover, AND used one of the longer 80mm length bolts on the breather cover. It bottoms out before clamping down, so that idiot used washers to compensate.  Noted and added to the list of shame.

Engine installed!(see pic)

Just some concluding work, and pushing on to fire it up!

[calj737]

Are your socket head screws black oxide? Or did you find a source for plated SS versions? If they're oxide, they'll rust very quickly and you may be very disappointed with the durability for an external application.

[70CB750]

Were you able to use those valves and springs from me?