Topic: 1976 CB750F - first bike, first build - mild cafe

[riffman12]

Bought it with 18k on the clock for a good price with a ton of new parts in a box (tires, SS brake lines, rebuild kits, brake pads etc.)

The bike ran (albeit kind of rough) when I bought it, so I'm doing my best to avoid opening up the engine for now. i want to ride it for a bit and get used to it before I do a full rebuild.


Had a lovely Windjammer on it when I bought it:




Pulled the seat and the tank to see how things looked underneath. I was happy to see no rust. Just some nasty dried battery acid from a mishap in the past:




Mid teardown:




And here's how it sits as of a few days ago. Forks are on now + new headlight




Things I've done so far:

- rebuilt the forks with new seals, new piston rings, and progressive springs

- installed new tapered steering bearings

- adjusted valves

- powder coated all the major parts, painted the front fork lowers and brake rotors with black epoxy paint (pics to come)

- Installed new wheel bearings


Things I'm waiting to install:

- Brass swingarm bushings (went through this loop once, but didn't notice I had some dinged metal on the end of my swingarm collar/tube that destroyed the brass bushings. Time to smooth it out and order another pair.

- Hagon Shocks

- Carpy 4 into 1 pipe, ceramic coated silver

- clubman bars (and drill for the controlls)

- Twinline cycles seat (paint and upholstery)

- brakes (all disassembled. need to paint and reassemble with new seals)


Other projects:

- clean and rejet the carbs for the new exhaust

- paint the seat and side covers to match the tank

- consider rear sets

- wiring



I'll try and do a better job of keeping this thread updated with new progress. It's been fun so far.

[Bigsam302]

Sounds like a fun project.  Good luck with it!

[Jerry Rxman Griffin aka MuthaF'er]

Looks like you found a really nice bike. Babied. Upgraded front end and wheels too.

[riffman12]

Yep the front end rear end are from a '77. That combined with the CBX wheels that I ended up buying has caused a real pain for getting a rear sprocket 

[SOHC4 Cafe Racer Fan]

Riffman,

Looks like a nice #2 seat from Ian Halcott (Twinline).  Those F2 brakes are pretty good, too. 

I say reinstall the Windjammer!  Just kidding.

Looking forward to seeing this come along.

[riffman12]

Riffman,

Looks like a nice #2 seat from Ian Halcott (Twinline).  Those F2 brakes are pretty good, too. 

I say reinstall the Windjammer!  Just kidding.

Looking forward to seeing this come along.

God no, I tried to give that Windjammer away with no takers. It's now sitting in a dumpster.

And yes correct on the #2 seat. Any ideas on a good way to mount it? I'd like to have it mount in such a way that I can remove it without too much hastle, to get to the battery etc.

Also need to find someone who can do a nice job on the upholstery. It's kind of just a hunk of metal at this point. 

[SOHC4 Cafe Racer Fan]

Cal's is an easy, effective option.

Another option is to weld it some simple steel mount tabs.  Take a look at these for an idea:  http://www.lossaengineering.com/collections/motrocycle-parts/products/lossa-seat-tab-kit

I tried Frankenstuffs rubber tabs that clamp around the seat rails, but the heat from my oil tank (in my 750) cause the rubber clamps to crack.  It was a bummer because the idea was great, did not require welding and the rubber provided some dampening.

[riffman12]

Install a 6mm rivet nut in the seat hoop rails, on top. Drill corresponding holes thru the seat pan, install button head cap screw from the top with a fender washer. Done, clean, simple, and easy.

I like simple, clean, and easy. Is it something you can remove reasonably quickly? I worry that it could be finicky to get on and off with my oil tank in the way. Do you have any pictures?

Another option is to weld it some simple steel mount tabs.  Take a look at these for an idea:  http://www.lossaengineering.com/collections/motrocycle-parts/products/lossa-seat-tab-kit

oh I like the look of these... I'm just not sure if it would be a big pain to get the seat on and off if I have my stock electrics / oil tank location.

I'm thinking if there's possibly a way I can slot the front into something (like a little hook) then just have fasteners in the back. Or maybe even a hinge in the back and fasteners in the front.

if only I could weld...

[SOHC4 Cafe Racer Fan]

There are plenty of welders in SF. 

[Kimosobey]

Looks good. Off to a good start. Following along

[SOHC4 Cafe Racer Fan]

Also need to find someone who can do a nice job on the upholstery. It's kind of just a hunk of metal at this point.

Contact Ian.  His wife Carolyn does great tuck and roll and diamond quilting upholstery. 
805.242.8265

[riffman12]

thanks for the tips so far.

Last night I attempted to put my rear wheel bearings in. Ended up fudging up the retainer threads on the smaller side, both on the retainer and inside the hub.

Tried chasing the threads with a bolt with threads to match, but no luck. Looks like I have a date with the machine shop in my near future. Really hoping the hub is still salvagable 


This weekend I'm hoping to get the clubman bars drilled, and cut off some of the unnecessary brackets at the rear of the frame.


Also, quick question: I need to rejet for my Carpy 4 into 1 exhaust. I will be running the stock airbox - NOT pods. If my factory main jet is a 105, should a 115 be big enough?

Also, is this the right jet for a '76 750F? My bike isn't listed...

http://4into1.com/genuine-keihin-round-main-jets/

[riffman12]

you may not even require a re-jet. at mosy i might suspect a 110.

hmm really? Carpy said at least 2 sizes up. I've also read the '76 F's ran a little lean from the factory for emissions purposes.

[SOHC4 Cafe Racer Fan]

FYI - Ian and his wife Carolyn are currently out of town (in Washington state).  They should be back next mid-next week.

[riffman12]

So i just installed the swingarm with brass bushings. The bushings went in with just the force of my hand once they were frozen and greased. I don't feel any play though.

Is this normal?

Also, how hard should it be to move the unloaded swingarm once it is torqued up? Mine moves but takes a bit of force.

I'm worried the bushings may be spinning in the swingarm instead of the collar spinning in the bushings...

[riffman12]

some small progress this weekend. Didn't have as much time as I had hoped.

Installed the swingarm (see my questions above...still not sure about this). My cat was a big help.




Got my Hagon shocks on as well, then realized I gave away the bottom bolts with the old shocks. Oops




Finally managed to free these guys. Going to open them up, clean them, and rejet them this week




Oh and I started accumulating some gear for when this thing is done. Helmet and pants are being shipped this week 

[SOHC4 Cafe Racer Fan]

Dianese makes excellent high quality gear. It's a little pricey but it will protect you.

[riffman12]

Dianese makes excellent high quality gear. It's a little pricey but it will protect you.

yes that seems to be the consensus. This was actually a one-off jacket they did exclusively for Cycle Gear called the Zen Evo... runs a little bit cheaper than the normal Dianese stuff.

I chose it mostly because it's heavily perforated with a removable liner - should get me through most of the year.

At the moment I'm battling with fit. It is preeeetty snug which is good, but I can't really cross my arm without the back feeling like it's pulling. I feel like my arms will be swimming in the armor if I size up though

[SOHC4 Cafe Racer Fan]

It will likely stretch out with use but you could also size up and pay for alterations, which can be pricey for leather gear.

[riffman12]

so last night I tackled the carbs. Unfortunately no pictures as I had dirty nitrile gloves on the whole time. I need to hire a photographer...

Everything looked reasonably tidy in there. The only mucky gunk was in the little bolt with the filter where the float needle sits. I pulled all the jets, blasted everything with carb cleaner, put the 115 mains in, and replaced all 4 float bowl gaskets. I left the carbs all attached to the rail and did not mess with the top of the carbs.

Few questions:

1) I didn't realize I was supposed to be able to look through a hole down the length of the pilot jet. The little side holes were nice and clear, but I think I need to go back and clean the center bore of the pilots. Any advice? I was thinking of just soaking the 4 pilots in carb cleaner overnight.

2) I didn't mess with the floats yet. I know I'm supposed to measure how far they drop down and adjust from there...but do I just hold the carbs up like they would be on the bike and let the float drop all the way down? Or just when it stops making contact with the needle?

3) I'll be running a Carpy's 4 into 1 with a stock airbox  with a K&N filter inside. Along with switching from 105 to 115 mains, am I likely to have to move the clip up or down on the needle as well? Do I need to completely disassemble the carbs to do this? Take them off the rail and all that?


Thanks again everyone for all the help so far. Much appreciated. I'll try and take some more pics when I open them back up to do the pilots.

[Gooseman]

Definitely want to check that you can see light through those pilots!  Compressed air is useful to clear them out after a soak as well.

Float measurement is easiest with the carbs upside down, at an angle so the floats are hanging just starting to touch the needle.
Great resource with picture instructions:  http://www.salocal.com/sohc/tech/carb/asmpg_mgs/flthgt.htm
You don't have to seperate the carbs to change the needle clip position, but you do have to pull away the throttle body to unscrew the tops obviously.
I wouldn't go moving needle yet, start at stock position, middle groove, get main-jet right and idle circuit dialed in and see how it is.

I have a 76F with carpy 4into1 as well, I think you'll absolutely need to jet up a bit, it's a very open pipe.  115's should be good to start, do a wot plug chop and if looks rich start stepping down.  I've been through almost every intake option since i built the bike and have a full set of jets from 105-130, mainly just because i like to play.  I've run open stacks, uni-filter pods, and the stock airbox now with k&n filter & intake modding. I'm actually in the process right now of leaning it back out for the air box.  Just like anyone will find with 5 minutes research, i could immediately feel the throttle transitions are way smoother with the airbox and no turbulent air passing things on the highway.

I currently have 122.5 mains and 42 idles with needle one clip richer from running v-stacks, it's running very rich all around with airbox now obviously.  No black smoke but fuel ring on the plugs is black and sooty and it feels lazy.  I'll be taking them back to 40 idle 118 mains this weekend to see how that is.  Will be interested to hear how yours looks with the 115's.

75/76F is my favorite, looking forward to seeing more of yours as you  progress.

[riffman12]

JUST the advice I needed. Thanks a lot for all that.

Last night I double checked all the pilots and I can in fact see light through them...I must have been delusional the other night. Or the carb gremlins got in and cleaned them.

Got a long list of things to do this weekend, including help my buddy pick up his '78F.

Will take pics this time

[riffman12]

So today was productive. Finally got an angle grinder and got to work with the frame modifications. I apologize in advance for anyone who tells me I'm a horrible person for cutting the frame.

The damage. I haven't gotten to it yet, but I will be grinding and sanding everything smooth + painting:








here's what I'm really happy about. I think if I cut about an inch off the front of my seat, I should be able to use the factory rear frame hoop.






You can see here how much I need to cut off to stop it laying under the tank, about an inch. I considered having it just sit under the tank but I think when the tank moves around it will clang around on the seat pat and be annoying




My plan is to put some sort of hooks for the front of the seat to slot into. Then I can use the factory hoop at the rear to bolt some sort of L brackets into the back of the seat pan with flat heads on the seat side. Then maybe even wing nuts so I can take the whole thing on and off quickly. Not totally decided on all this yet.

But I'm just happy I don't need to weld in a new hoop 


Next steps:
- fix my buggered up threads in the rear wheel bearing retainer, get the rear bearings in.
- mount the wheels, get it off its milk crate
- mount my exhaust
- get her running once again

[SOHC4 Cafe Racer Fan]

I spoke with Ian.  If you are interested, the best method for upholstery would be to send him the seat when you finalize the length.  That way the pan will be dead nuts on and the build up for the tank as well.

[riffman12]

sweet thanks. Once I have the seat pan all ready to go I will give them a call.

Quick question. I bought these Hagon shocks, but it looks like they're a little wide for the normal mounting spots. Do I need to put washers in there to take up the extra space?

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