Topic: 1975 CB750 rebuild into a Bobber!! First time so be kind!

[ffemt2466]

Ok, I was posting in other areas and realized this is probably the best place for my build and updates. A little background on my build; I found this bike on Craigslist and snatched it up for $100! It's a 1975 Honda CB750, the motor was stuck but it rolled and shifted fine. It came with a box of parts as well. It sat in my garage for about a year but I now have time to get goin on it.

I want to rebuild this thing with as minimal cost as possible but also doing as good a job as I can and job out the rest. My end goal is to have an old school bobber look. I don't have the expertise to hardtail this so my thoughts are to get lowering blocks and drop down to 11" shocks along with possibly a sporty tank and 14" ape hangers. Thinking flat or glossy black with whitewall tires and red painted spokes.

I had taken the bike down the road to a shop to see if he could unstick the motor for a reasonable price, didn't happen. He said he can rebuild it but it wouldn't be cheap, recommended I give it a shot, hell worst case I'm out $100. There is my motivation!

So far I had my brother help me lug it up onto my table and start crankin. I built the table and realized we needed to take the rear wheel off just to get it to fit ok. So rear wheel and chain are off! Then I popped the tank off and started to pull parts off enough to get the motor out. Carbs set aside for now (have a buddy that said he'd help me and show me how to rebuild them, was scared at first but gotta learn how they work and how to fix em!)

Now my brother and I got the motor out, way easier than some people say on here, just pulled mounting bolts and wiggled er out the right side of the frame. Got the valve cover off and started to pull rocker arms off, got stuck with the cam for a bit, mostly due to the motor being stuck still, after a little struggling we got it off. Came was next and then the rocker towers.

Removed the head nuts off in reverse order and started to try to remove the jugs. It appeared that the #4 piston (far right side one) was stuck in the cylinder. After some soaking with Seafoam and some tactical smacking I managed to bust it loose and the crank finally was able to turn freely!! Set aside the jugs and the valve head to get to the machine shop asap (hopefully today!) Unsure at this time if I will need to bore or simple hone on the jugs, guess I'll wait and see.

Over the past weekend I was able to get the frame scrubbed and powerwashed and cleaned up the valve cover. Today other than machine shop shopping I am going to keep workin on cleanin up the frame and other parts. I have the benefit of using my dad's bead blaster for some of the smaller parts later.

I will post a bunch of pics with this and I appreciate any comments, advice or ragging lol! Hope you enjoy!

-Joe

[ffemt2466]

Anyone know how to post more than one pic per post?

[ffemt2466]

Ok, I shrunk em down a bit, let's see how this works!

[ffemt2466]

Couple more pics

[ffemt2466]

And more!

[ffemt2466]

Last set for now

[ffemt2466]

So I ordered a sand blaster online and just waiting for it to come in. Got some quotes for the valve job and boring or honing the cylinders. Is there anyway to tell if the rust from the frozen piston will just cause a hone or a bore? What should I use to clean it and possibly hone it myself? Also is just a simple green mix a good thing for the carbs to soak in for cleaning? Do you always have to change the o-rings in the carbs? Can ya tell I'm cheap? Thanks!

[MasterChief750]

the machine shop would be the best judge of whether or not you can just hone it. simple green mix is really good and you should replace all the orings and float needles. im cheap too but gotta do things right or you will be doing it again.

[ffemt2466]

I was planning to get a 5 gallon bucket full of simple green mix and soak the carbs, heads and jugs for awhile, then a pressure wash and possibly a soda blast. I got my sandblaster in and it works well, just slow. Got bout half the frame stripped and tried for a min or two for the soda blast on the carbs, need a little tweaking to it. Got ahold of a few machine shops and prolly gonna take the parts, after cleaning, to a few this week.

I also found a guy with a rear wheel in better shape and a set of 14" hangers, waiting to hear back from him about an airbox and an oil tank. Also trying to find another set of gaskets as CycleX is currently out of stock. Slow build but once I get the machined parts back and my gasket set it should move a little quicker!! In the meantime its gonna be cleaning and painting, also shopping for a sporty tank, shorty shocks and lowering blocks!

[ffemt2466]

Got the sand blaster working pretty well, slow but works good! Got some before and after on a wheel, still needs a little work. Cleaned the heads up a little bit with some carb cleaner. Gonna still dunk and soak in simple green, probably Sunday. Got a quote to bore the jugs for $180 total and think I'm gonna do that with the big bore kits from ebay. Anyone think that might not be a good idea? Figure $180 for bore, $110 for piston kit, $75 or so for gasket kit and if valves are still good $0 for that, anything I might be missing? I still need an oil tank, airbox and some other various small parts.

[ffemt2466]

And more

[lucky]

Anyone know how to post more than one pic per post?

Photos are still too large.
Should only be 640x480 pixels max.
Even a 640x480 just barely fits my large MAC screen.
Smaller monitors it would be worse.
The viewer would have to scroll to see the whole pic.

[ffemt2466]

Think I got em right on here now, seems to work better when I shrink em down. Just an update on the bike, frame almost all the way blasted and other parts soaking in Simple Green until tomorrow when I can get scrubbin and then its machine time!! It's been beautiful here and I want this thing on the road ASAP!!!

[ffemt2466]

Just an update, found one of the pistons was cracked and now fishing parts out of crank. Got my gasket kit in and oil tank on its way. Spoke to a member on here and set up a deal for new pistons, just need to measure and then hopefully hone and reassemble soon!

[ffemt2466]

Ok, so been a few weeks since I updated. Got some more pics to add. So since last update, fished most of piston out of crank, just got engine onto stand to drop the pan and get the rest. Got ahold of a member on here and got hooked up with new pistons, rings, cylinders and valve cover (you'll see in pic mine ended up cracked). Frame is about 95% done in sandblast booth, I work on it when I don't have anything else to do. Got swingarm and battery primed, gasket kit, oil tank are in, airbox is in transit! I've been working on getting the wheels ready. Got a buddy that has paddles so we can take tires off, finish blasting and prep for paint. Gonna paint em red for the whitewall tires!

Anyway here are some more pics. I put a red line across the back of the frame where I want to cut it short, will that work ok? I've seen a few on here with that same cut. I want to put LED tail lights in the holes from the cut? Thanks and hope someone cares I'm documenting lol!

[Retro Rocket]

Anyone know how to post more than one pic per post?

Photos are still too large.
Should only be 640x480 pixels max.
Even a 640x480 just barely fits my large MAC screen.
Smaller monitors it would be worse.
The viewer would have to scroll to see the whole pic.

You may have to buy a decent computer Lucky, the pics seem to be fine for everyone else, one more thing, i use photobucket and it auto resizes my pics for the forum, i have never had to resize any pic ever, including huge camera shots..

[ffemt2466]

I started shrinking my pics on paint just to fit more in here.

[ffemt2466]

Anyone have any info on the frame cut??

[JimJamerino]

You can cut the frame there, but remember that bracket holds your rear fender and adds some strength to the butt of your bike.  Before you lop it off, consider your plans for the fender and possibly reinforcing the hanging legs, especially if you're not hardtailing it.

[lucky]

Just an update, found one of the pistons was cracked and now fishing parts out of crank. Got my gasket kit in and oil tank on its way. Spoke to a member on here and set up a deal for new pistons, just need to measure and then hopefully hone and reassemble soon!

Better measure those cylinders and see if they need boring before honing. Something caused that piston to crack.

[ffemt2466]

I plan to make or find a short fender and either weld it between the frame sections back there or bolt it in. I have seen others like that and they seem to be fine.

As for the piston, I broke it myself on accident when I was turning the crank and not being careful enough. I just received my pistons, jugs, and valve cover yesterday so I will be beginning asap!

Also I got the tires off the rims last night, gonna blast em asap then I will have alot of parts ready for paint! 

[ffemt2466]

Ok another update, I managed to fish all the piston parts out of the crank (see pics) ended up finding a crack in the valve cover (pics) so I ended up scoring some parts from a member and landed new jugs, pistons, rings, and valve cover. Got those parts in and all ready for motor re-assembly. In the meantime I managed to get both tires off rims and cleaned them up ready for paint. Put first coat on swingarm and battery box and I'm pretty happy with the satin black so far! Just have a few speedbumps to get over and order a few more parts but I'd be thrilled if I could get motor back together and painted by end of next week!

Here is a list of what I need still;

Peanut or Sporty Tank
14" ape hangers
front and rear whitewall tires
clean looking throttle, clutch and front brake assemblys
forward control, either designs for some or just end up buying em
shorty shocks
lowering blocks
carb rebuild kits
headlight/speedo combo
brake pads front and shoes for rear


Thanks for reading, here are some updated pics!

[nayto550]

You're going to replace the wheel bearings, right?

Oh, and here's the light/gauge combo that I got for my bike.  The bucket seems to be pretty high quality, the speedo not so much, but it looks nice.

Interested to see what comes of this.

[ffemt2466]

I like that setup with the speedo light combo, I bookmarked the page and will probably order one. I have a few other ideas for that but that one might be the easiest way to combine and keep a clean look.  I am ordering wheel bearings today, I still need to find a good place for tires so I can hopefully get it to be a roller asap! That damn search function not working sucks right now!

[ffemt2466]

So update time! Yesterday I was able to get second coat of paint on swingarm and battery box, second coat of prime on front wheel. Also I managed to mic and hone the cylinders and mic the pistons and everything looks good! Then got started on turning the valves. Got 5 of the 8 valves done so far but baby steps! Almost ready for re-assembly!! Gonna order some more parts and then hopefully get rest of valves done before end of weekend, then lay out all motor parts in order of assembly!!

Joe