Author Topic: 1975 CB750 F0 Cafe - First Build Ever  (Read 5569 times)

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Offline drrice

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1975 CB750 F0 Cafe - First Build Ever
« on: December 22, 2011, 02:12:55 am »
So here I am. Pretty much a bike noob. I am handy around cars but it's been awhile. I will be starting on my project this week. I plan on building a pretty moderate cafe build. Here is my bike as it sits.

















I'm going to jump head first into the build. Here is a list of my plans. I feel kind of lost and I'd love for anyone to chime in on their experiences on where I can get the best bang for my buck based on previous experiences. My main questions are in brackets.

  • Clean the carbs
  • Check clearances for the valve train
  • Check hoses and lube cables
  • Seal any leaks [Should I just get a whole gasket set now and do it all?]
  • Paint the motor
  • Polish some covers and hardware [Anyone have a good guide on how to polish?]
  • Clubman bars
  • Run wires through the frame [Is this worth it? Can I do this with the stock harness? Should I buy a replacement harness due to old wires/breaking connectors anyways?]
  • Restore gauges
  • Swingarm bushings [Can I replace these myself? Or should I just upgrade to the dresda while I'm at it?]
  • Steering head bearings [What's the best ones I can get, I heard the timken's aren't offered anymore]
  • Forks
  • BCR tank/seat combo, I'm doing my own battery box

I am also definitely going to lower the bike. I am 5'5" with ~29" inseam. I have heard I can lower the shocks/forks or get smaller wheels. What are the pros and cons between these two choices? Can I do both, or is this not conducive to handling/clearance?

I am going to start off tomorrow with the carb cleaning and maintenance.

My budget is ideally around $2000.

Thanks in advance
« Last Edit: December 28, 2011, 09:13:36 pm by drrice »

Offline SHORTROUND

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #1 on: December 22, 2011, 05:59:49 am »
Welcome to the madness.  ;D
You'll find a wealth on knowledge and experience here. So i''ll chime in with my 2 cents on your questions.
#1 Don't just clean the carbs rebuild them. Best $50 you can spend.
#4 Yes, buy a gasket kit.
#6 search the site, there is also some instructions on the Cafe Racer TV site.
#8 if you are going to run the side covers it's not necessary. Worth it? only you can deside.
#11 i bought a couple of sets of Ebay. They came from england?

#13 BCR fiberglass tanks are garbage; poorley made, delaminate, and don't fit weel.

Good luck with your build.

Offline drrice

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #2 on: December 22, 2011, 06:19:53 pm »
Thanks for the insight.

I meant rebuilding when I stated cleaning. I didn't think much else went into a rebuild besides gaskets and O-rings. Should the needles and jets be replaced regardless?

I don't plan on running side covers. I'd like it to look neat. But I don't see where I can start running the wires without cutting into the frame.

I haven't read a negative review of BCR's tank/seat till yours. Do you speak from personal experience. I just sent in my deposit. damn.

Offline Blackandsilver

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #3 on: December 22, 2011, 11:18:04 pm »
Hey hey. I just started on a 750 too. 
Here's two cents.
First:
If it's not leaking and it's running fine, don't pull the motor.
They are a heavy awkward sob. If you do pull it, do a bunch of maintenance.
Like cam chain, can chain rollers, guides and guide rubber mounts.
And yes buy a gasket kit and replace everything you can.
If you have the cash it's not too expensive to bore them out too.
Second:
Take your seat off before you say you are too short. Building a low profile bump seat can help s ton with bringing the bike to a rideable height.
I put an 18" rim on the front if mine and lowered the forks in the trees about an inch.
Careful with lowering #$%* though because your kickstand will become too tall.
Third:
Polishing... There's lots of ideas on it. Gnarly stuff like gouges can be sanded out of aluminum with 120 grit paper and then just work your way finer till you get to 600 or so, then use a buffing wheel or polishing compound. It takes a lot of time if you don't have power tools. But if you have even a drill you can put a buffing wheel on it. And " mothers" aluminum polish to finish the job. If your stuff is just tarnished or lightly oxidized try autosol or mothers fisrt and save all the hassle of sanding. You'll get a feel for it in no time.
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Offline Blackandsilver

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #4 on: December 22, 2011, 11:32:16 pm »
Fourth:
Don't run your wiring through the frame. You're asking for trouble there
Fifth:
All balls tapered roller bearings for your steering head
Sixth:
I'm sorry to say, but yeah, bcr tanks are crap. That tank you have is what I am running, they look awesome cleaned up and painted well.
Good luck with everything.
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Offline wedoo2

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #5 on: December 23, 2011, 04:22:26 am »
Going to follow the build.  As for the tank, you may want to read through this before you pay money to BCR. 

http://forums.sohc4.net/index.php?topic=76445.0

I could not afford him anyway so it is a mute point for me.  Beside, I like your tank and think them to be perfect for the cafe build.  There are plenty of examples of great builds here that prove that.

The bad thing about the cafe build is most people loose that back body extension on the 750.  It reminds me of a Suzuki 1000 / 1100 and I think they look great.  But the chrome grab bar looks dumb.  Way too long.

Also, rebuild the carbs.  Don't even debate it.  (Someone will)
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Offline SHORTROUND

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #6 on: December 23, 2011, 06:02:10 am »
Thanks for the insight.

I meant rebuilding when I stated cleaning. I didn't think much else went into a rebuild besides gaskets and O-rings. Should the needles and jets be replaced regardless?

I don't plan on running side covers. I'd like it to look neat. But I don't see where I can start running the wires without cutting into the frame.

I haven't read a negative review of BCR's tank/seat till yours. Do you speak from personal experience. I just sent in my deposit. damn.

their metal tanks are awesome, but the fiberglass tanks are a hybrid using stock filler necks and stock bottoms.  Mine had 1/4 inch of bondo in cartain places witch explained the absence of gel coat. coated the inside with castwell sealer. bike looked great but started running like S%$t. 2 weeeks  later the paint was poping arount the filler neck seams. They sell alot of them so maybe mine was just a defect. but i would never buy one again.

Offline ekpent

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #7 on: December 23, 2011, 07:05:20 am »
Noticed that your speedometer is from a 71 K model.Has the lights in the case. May want to source up a correct F model sometime,probably could sell the old one here.

Offline drrice

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #8 on: December 24, 2011, 01:12:52 pm »
Wow thanks for the input guys. Now I am really worried about putting a deposit down on that BCR tank. I didn't see many good examples with the tank I had on my bike. #$%*. I'll talk with Benjie to find out what the case with his fiberglass tanks are. In the mean time I will look for solutions to keep the inside of the tank together.


their metal tanks are awesome, but the fiberglass tanks are a hybrid using stock filler necks and stock bottoms.  Mine had 1/4 inch of bondo in cartain places witch explained the absence of gel coat. coated the inside with castwell sealer. bike looked great but started running like S%$t. 2 weeeks  later the paint was poping arount the filler neck seams. They sell alot of them so maybe mine was just a defect. but i would never buy one again.

Was your solution to coat the inside with castwell? Or was that what BCR put in? Is that what caused it to start acting up? Does anyone know of a fix for the fiberglass tanks?

*updates*

I started working on the carbs. I have already ordered the cb750f rebuild kit from cb750 supply. I got 2 day shipping but due to the holidays I probably won't get it until Wednesday the 28th. So I started cleaning the carbs for now.

Carbs Out


I started with Carb #4


The main gets were REALLY dirty, good thing new ones are on the way. Should I drill out the new jets before I put them in? I plan on using just pods and an exhaust.




Here is my soda blaster that I put together after seeing this link http://www.aircooledtech.com/tools-on-the-cheap/soda_blaster/



Carb 4 cleaned next to carb 3


There is cracking in the main jet housing, should I be worried about it?




Do I need to take out this bronze ball and clean it? (Circled in Red)



I also saw a site talking about removing one of the jet housings. I don't think this part is included in the rebuild and haven't seen the part anywhere really. Do I need to remove it? Site in question - http://www.salocal.com/sohc/tech/carb/dspg_mgs/rmvndljt.htm


« Last Edit: December 29, 2011, 07:27:34 pm by drrice »

Offline drrice

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #9 on: December 24, 2011, 01:19:27 pm »
Noticed that your speedometer is from a 71 K model.Has the lights in the case. May want to source up a correct F model sometime,probably could sell the old one here.

Yeah I noticed this as well. I plan on getting new gauges, I haven't decided if I was going to get aftermarket ones that were smaller, or go with 75F gauges yet. My priority is to make it run well, fix the frame, suspension, brakes, electrical. Then go over to the cosmetic pieces.

Anyone know a good source for new enginge bolts? The ones that go over the alternator, valve, and starter? I see cycle X has some but they are about $80.

Offline Stev-o

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #10 on: December 24, 2011, 01:53:18 pm »
I would nt use the stock gauges, sell em. Go for small aftermarket, my cafe only has a speedo.

What engine bolts, for the covers? If yes, here are some for $40...

http://www.ebay.com/itm/Complete-80-pc-Stainless-Steel-Screw-sets-Honda-CB750-/260919288972?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item3cc000648c#ht_500wt_922
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer.....K5 Fiddy Dolla Special!......and a Bomber!............plus plus plus.........

Offline drrice

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #11 on: December 26, 2011, 09:53:42 pm »
Can anyone identify this exhaust?










Offline Cheffish

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #12 on: December 26, 2011, 10:58:51 pm »
Looks like a Mac

Offline Retro Rocket

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #13 on: December 26, 2011, 11:39:08 pm »
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline drrice

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #14 on: December 28, 2011, 08:51:04 pm »
So I've basically almost finished stripping my bike. I did the .45 casing fix for the carb main jet tower cracking. Here are my casings all ready to go in.



I also found some new O-rings for the Fuel line connectors between the carbs. The channel for the inside ring was a bit narrower so I used 2 different types of O rings. The outside ones are thicker. They are from Wurth.

Inside O ring


Outside O ring
« Last Edit: December 28, 2011, 09:14:29 pm by drrice »

Offline drrice

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Re: 1975 CB750 F0 Cafe - First Build Ever
« Reply #15 on: December 29, 2011, 07:10:26 pm »
So I tried the rubber restoration with wintergreen oil which is talked about in this thread http://forums.sohc4.net/index.php?topic=29707.0

I decided to use a 8 oz of wintergreen oil to 1 gallon (128 oz) of water to submerge and heat the rubber components over [1 oz:16 oz ratio]. I tried to keep the water from boiling and just get the water rolling.

I did my 2 drain hoses, fuel lines, and 4 carb boots.

Here are the boots beforehand, pretty dry and not pliable. I couldn't compress them at all.


Here they are being boiled. I got the large 1qt of wintergreen from HDM for $17.00 USD http://www.hdmworld.com/tirepreps.htm


After 35 minutes of treatment


This is right after treatment. They have hardened up a bit more since drying completely but are still are much more pliable. [excuse my friend from making odd faces in the picture]


Also my carb parts finally came in. So reassmbly can now take place.