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Offline R1gg5

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One Piece at a Time CB750
« on: May 17, 2013, 12:26:42 PM »
Hey everyone-

I got a steal of a deal (may include future sarcasm here) on a early 70s CB750 a couple of weeks ago - just $250!

Here's what I know, and I have some questions at the bottom for those of you who are willing to lend some expertise! (start humming Johnny Cash's "One Piece at a Time"… now!)

The frame is a 71'
The engine is a 72'
Looks like forks are 74'
Wiring has 3 fuses, so not sure on the year there.
Seller said engine is rebuilt, but I'm doubting this.
Clutch outer seal apparently leaked and clutch discs went dry. I need to fix the leak and re-wet the plates.
All suspension feels tired or done.
4 into 4s 341 in mostly great shape!

See some photos here: http://www.youtube.com/watch?v=R3dWbqq5UBs (I just posted the video, so you may have to wait for it to be visible)

The dude I bought the bike from said he had three different CB750s, and he paid a guy to produce one solid bike between the three. So what I have is kind of a "frankenbike". He couldn't recall what years he had as donors - but the vin and engine vin clearly indicate there were parts from a 71 and 72. Third donor bike is unknown to me. The seller told me that when he parked it four years ago, it did run and it ran well.

It kicks over. Tank is clear and clean. With some jerry rigging, I can get the starter to engage when you push the "start" button. Fuel lines need to be replaced, not sure on carb condition. Wiring is a mess from first glance, and not sure I'm getting juice at the points- they were left uncovered the past couple of years. I really want to just get a good harness and replace the wiring altogether - if affordable.

What I've done:
• Oil change with new filter and o-rings (now have a very slight leak near the filter)

So my questions:

• Best way to fix a very slight oil leak at the filter?
• My wiring has the three fuse version. Why do I need that? What do those extra two fuses do? With all the various franken-components on the bike, could I more or less treat this like a 71' and go back to a single fuse harness?
• What are the bare essentials for wiring so this will run?

I only want to get this girl to start up and run (or at least attempt), and once that's done, I'm going to strip her down to the frame and start from there. Would love any advice or words of encouragement as I tackle this.

I'm so excited to have this little project to play with! When she's all done, she'll pretty much have the same look and feel, but newer and more shiny!

Oh- parts I'm interested in (in case anyone is willing to sell/part with):
• Proper hand controls for a 71
• Ignition mounting plate for a 71
• Correct 71 headlight bucket
• Not sure about forks - do I need or want 71 forks?
• CORRECT WIRING HARNESS! (or I may build my own)
• Whatever else you recommend I do to get this girl road worthy

I'm not wanting to spend a fortune on this CB, so would love pennywise advice. Thanks all!
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1975 CB750 Cafe Racer (finished)
1971,2,4 CB750 Frankenbike Project
1969 CT70 (Trail 70)
2015 Ducati Scrambler Classic (with minor mods to make her mine)

Offline lwahples

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Re: One Piece at a Time CB750
« Reply #1 on: May 17, 2013, 01:03:30 PM »
Nice bike, your vid says it's private. Good Luck on your search for the 71 parts.They tend to get pricey.
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Offline R1gg5

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Re: One Piece at a Time CB750
« Reply #2 on: May 17, 2013, 01:10:01 PM »
Video should be visible now…
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1975 CB750 Cafe Racer (finished)
1971,2,4 CB750 Frankenbike Project
1969 CT70 (Trail 70)
2015 Ducati Scrambler Classic (with minor mods to make her mine)

Offline 70CB750

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Re: One Piece at a Time CB750
« Reply #3 on: May 17, 2013, 01:41:57 PM »
Welcome! Nice score.

The forks can actually work for you - it is easier to do dual disc on later forks.

Where is the oil filter leak?
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Prokop
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Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline R1gg5

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Re: One Piece at a Time CB750
« Reply #4 on: May 17, 2013, 01:47:34 PM »
Quote from: 70CB750 on May 17, 2013, 01:41:57 PM
Where is the oil filter leak?

Dripping straight from where the filter housing cranks on. How tight is tight enough? I cranked it down pretty good. The leak is super slow… is it possible that the o-rings that came with the filter are crap? I put them on properly, wetted with oil, etc. Not sure the best solution on that one.

Thanks for commenting!
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1975 CB750 Cafe Racer (finished)
1971,2,4 CB750 Frankenbike Project
1969 CT70 (Trail 70)
2015 Ducati Scrambler Classic (with minor mods to make her mine)

Offline Johnie

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Re: One Piece at a Time CB750
« Reply #5 on: May 17, 2013, 01:54:38 PM »
You should only have to snug that oil filter bolt down. It is common on this board where we buy a 750 and end up cutting the filter off because the previous owner cranked it down to much. My hunch is the o-ring around the bolt shaft is bad.
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1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline lucky

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Re: One Piece at a Time CB750
« Reply #6 on: May 17, 2013, 01:59:21 PM »
"I cranked it down pretty good." Scares me.  It is not a car.
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Offline Bankerdanny

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Re: One Piece at a Time CB750
« Reply #7 on: May 17, 2013, 02:15:07 PM »
More fuses are better than less fuses, so work on fixing the wiring system you have rather than reverting to a 1 fuse system

Not much tightening should be required to seal the oil filter housing. It is possible that 'cranking on it' did more harm than good, it just needs to be snug, not tight.

Since you don't have the original engine there is no particular value to trying to get the whole bike to '71 spec.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline R1gg5

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Re: One Piece at a Time CB750
« Reply #8 on: May 17, 2013, 02:39:05 PM »
Just to clarify- I didn't over tighten the oil filter bolt. At first I just put it on snug, very little effort (afraid to break something), but it leaked real good. So then I snugged it up more, but with caution. It's by no measure on too tight- I always err on the side of safety so that I don't cause a more expensive problem.

I supposed that's why I'm asking now- I didn't want to tighten it anymore without input from those who know.

I'll pull it all off this weekend, inspect, and replace the o-rings if need be. Is there a torque setting for this?

and seriously guys - THANK YOU for your input. It's much appreciated as I cut my teeth on this exciting new project.
« Last Edit: May 17, 2013, 03:05:04 PM by R1gg5 »
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1975 CB750 Cafe Racer (finished)
1971,2,4 CB750 Frankenbike Project
1969 CT70 (Trail 70)
2015 Ducati Scrambler Classic (with minor mods to make her mine)

Offline Xnavylfr

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Re: One Piece at a Time CB750
« Reply #9 on: May 17, 2013, 04:38:03 PM »
The bare minimum wire needed to get it to run, is on the coils(UNDER THE TANK) is a BLACK with WHITE stripe that is Yd so both coils get power from the one wire...
Make a jump wire Yd and connect to both coils and straight to the + post of your battery.   This elimnates ALL other systems from the circuit except ignition..

IF you have GOOD POINTS(gaped correctly), GOOD sparkplugs and good gas flow circuit (CLEAN and SYNCED CARBS) you also have to include TIMING correct, the bike SHOULD start!!!  NO LIGHTS/NO HORN  just engine running!!


Xnavylfr(CHUCK)
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Offline 70CB750

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Re: One Piece at a Time CB750
« Reply #10 on: May 18, 2013, 04:01:36 AM »
I would check for flateness on the filter housing and the engine. With new o-ring it should not leak.  Used filter housings are quite available if you need replacement.
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Prokop
_______________
Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline Johnie

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Re: One Piece at a Time CB750
« Reply #11 on: May 18, 2013, 06:14:08 AM »
Some guys had problems with aftermarket filter o-rings...they were just a bit narrower and leaked as compared to the Honda brand. Not saying all aftermarkets are bad, just some had issues.
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1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline ekpent

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Re: One Piece at a Time CB750
« Reply #12 on: May 18, 2013, 07:39:37 AM »
Gas tank is off a 75 or 76 if your wondering about donor years. Think you better be looking for some fresher points by the looks of the rust.Extra fuses in later models were for the headlight and tailight loops.
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Offline phil71

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Re: One Piece at a Time CB750
« Reply #13 on: May 18, 2013, 08:10:19 AM »
I think your problem is time management. If you'd have been replacing your points instead of making musical slide shows you might be up and running.  In the pics, what I'm seeing is a wiring harness that's not completely hooked up, or tucked where it should, but I don't see any signs of bastardization . Wiring in the bucket was a rats nest when it was new, and your LH electrical components, while not mounted, all seem to be there and connected.  Get a tetanus shot, and get those barnacled points out of there.
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Offline Johnie

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Re: One Piece at a Time CB750
« Reply #14 on: May 18, 2013, 09:49:07 AM »
Just wondering...how does the gas tank interior look? I did like the video...one thing I have noticed on this board is we like pics here. Good job with the music and all... :)
« Last Edit: May 18, 2013, 09:51:11 AM by Johnie »
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1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline R1gg5

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Re: One Piece at a Time CB750
« Reply #15 on: May 18, 2013, 06:49:57 PM »
Gas tank interior was super clean. I ran some gas through it and it comes out perfectly clear.

My gas lines at the "T" are junk, so I will pick up some replacement hose soon for that.

----

A friend of mine suggested cranking the engine over with the points just to see if they were sparking or not, so that's why I did what I did with the points. I'll likely change them out. I also have new plugs that I picked up and will replace those soon.


----

By the way guys- the video took me all of 2 minutes to pop up on YouTube- even with the music. I figured it was simply the VERY FASTEST way I could present quite a few images in high quality without much trouble. It's more of a slideshow anyway. Adding the song took 10 seconds. It's funny to see the reaction I'm getting over something so simple.
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1975 CB750 Cafe Racer (finished)
1971,2,4 CB750 Frankenbike Project
1969 CT70 (Trail 70)
2015 Ducati Scrambler Classic (with minor mods to make her mine)

Offline ekpent

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Re: One Piece at a Time CB750
« Reply #16 on: May 19, 2013, 04:46:51 AM »
I liked the video,Johny Cash works for me and the song fit yor project well.
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Offline Johnie

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Re: One Piece at a Time CB750
« Reply #17 on: May 19, 2013, 06:39:07 AM »
The next video will be of this bike purrrrrrrrrrrrrrrrrrrrring like a 750 should. :)
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1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline bjbuchanan

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Re: One Piece at a Time CB750
« Reply #18 on: May 19, 2013, 06:33:25 PM »
Don't worry about the video comment. Two finger typers probably think anything like that on a computer takes a while. Check out the link I'm attaching, it can be useful to you possibly with the points

From the looks of it hit the hardware aisle and get some fresh hardware for the points plate

Have fun and enjoy
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The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline R1gg5

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Re: One Piece at a Time CB750
« Reply #19 on: May 20, 2013, 02:21:41 AM »
Quote from: bjbuchanan on May 19, 2013, 06:33:25 PM
Check out the link I'm attaching, it can be useful to you possibly with the points

Hey bj- looks like you missed the link- please send that if you can find it… and thanks for the comment!
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1975 CB750 Cafe Racer (finished)
1971,2,4 CB750 Frankenbike Project
1969 CT70 (Trail 70)
2015 Ducati Scrambler Classic (with minor mods to make her mine)

Offline phil71

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Re: One Piece at a Time CB750
« Reply #20 on: May 20, 2013, 11:38:46 AM »
Sorry, that was just a little joke. Admittedly, I hate making videos, and it may take forever, or just feel that way to me.
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Offline bjbuchanan

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Re: One Piece at a Time CB750
« Reply #21 on: May 20, 2013, 04:09:28 PM »
Quote from: R1gg5 on May 20, 2013, 02:21:41 AM
Quote from: bjbuchanan on May 19, 2013, 06:33:25 PM
Check out the link I'm attaching, it can be useful to you possibly with the points

Hey bj- looks like you missed the link- please send that if you can find it… and thanks for the comment!

http://forums.sohc4.net/index.php?topic=121142.0

That should work

Hey phil,

Depending on time you can whip these videos togther quick, sometimes easier than uploading. My easygoing-ness doesn't translate well to typing, I usually sound like a D!ick really, so I understand
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The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline phil71

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Re: One Piece at a Time CB750
« Reply #22 on: May 20, 2013, 04:31:41 PM »
hahahaha, i know what you mean. Middltown's not too far from brooklyn. Let me know if you're stumped. I don't see much there that couldn't be sorted out in a few hours
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Offline bjbuchanan

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Re: One Piece at a Time CB750
« Reply #23 on: May 20, 2013, 09:25:04 PM »
I actually live in tarrytown now so I'm much closer. Work and school full time but I would really like to cruise with some other guys with my kinda bike, not just wander around Ttown scaring the locals with my smoker lol
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The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline Raul CB750K1

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Re: One Piece at a Time CB750
« Reply #24 on: May 22, 2013, 03:52:03 AM »
Quote from: phil71 on May 20, 2013, 11:38:46 AM
Sorry, that was just a little joke. Admittedly, I hate making videos, and it may take forever, or just feel that way to me.

FWIW, I found the joke real funny and not much offensive to the original poster. Just a hint of sarcasm, I found it funny.
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