[GLENNpm]

Hi all!

I inherited a couple mid 70's model Honda CB's from my grampa when he passed a couple years ago. He was a great mechanic. I am not. But I love him dearly and want to continue his legacy. So, now that I'm finally getting the time and money, I figure this is a good time to start learning. I'm going to start with the one that already runs. It's a '76 CB750 (as I'm told by my dad). From what I understand, it just needs some tires and work on the carburetor. But I'd like eventually overhaul it completely and turn it into a serious Cafe Racer. I figure the carburetor is the best place to start. Since I want it to eventually be a sleek Cafe Racer, I want to tune it for pod filters and performance exhaust. I think I understand the basics of re-jetting the carburetor from some videos I've found on YouTube. But my current knowledge is entry level at best and, depending on the presenter, YouTube isn't always the most reliable source. I'm a bit overwhelmed right now. I've done some Googling and I'm still not sure where/what parts to buy for my exact model of bike. If any of you could point me in the right direction for some good educational reources, I'd really appreciate it! I look forward to interacting with you all over the course of my builds and hope I can eventually learn enough to be of help to others.

 

[TrialsRider]

Hi, very cool that you have interest in fixing up your bikes,
and maybe even learning to ride them?

I have 2 things to say about your cafe racer vision, first is your CB750 has 4 carburetors,
second is; I been doing this motorcycle thing probably as long as your grandpa and pod filters, they were Never a thing, you are highly advised to scrap that part of the vision.

Best luck with your project Glennpm

 

[woodsman]

Grandpa would likely be angered by the trash being made from vintage bikes. Making a great sport bike from a honda 4 has nothing to do with grinders and bonelines. Cafer racers were always about improved performance, it had nothing to do with how a bike looks. Modifications that improved braking, turn in, acceleration out and stability at high speed was what were done and if you want something true to it's heritage then that's the direction you should go. Get the best one running in stock configuration, then start from the ground up replacing, tires, pads, lines, shocks, springs, rearsets, steering damper, bearings, bushings, sprockets, chain, etc. By the time you get to the top it'll be so much fun spanking the cafe posers you might want to leave the rust or dings.

 

[Teazer]

You got it all wrong. It's about skateboard seats clipons and knobby tires - a combination that assures the rider or hero-maker status. A legend in his own lunchtime. That combo assures that it is both uncomfortable and unsafe, and that confirms the hipster hero status.

Seriously though, forget all that you think you know about cafe racers and build the bike back stock and just ride the bloody thing. Then after a few thousand miles and near misses, work out what you want to change to make it work better for how you want to ride it.

Now that 'cafe Racers" are like arse holes in that everyone has one, it's easier to stand out on a stock looking time capsule that is fun to ride as well as cool.

 

[Geeto67]

Hi all!

I inherited a couple mid 70's model Honda CB's from my grampa when he passed a couple years ago. He was a great mechanic. I am not. But I love him dearly and want to continue his legacy. So, now that I'm finally getting the time and money, I figure this is a good time to start learning. I'm going to start with the one that already runs. It's a '76 CB750 (as I'm told by my dad). From what I understand, it just needs some tires and work on the carburetor.

Great! I love your enthusiasm. Here is what you need to do:
1. Get a factory service manual, as well as a Haynes or a clymer manual. You can download the factory manuals from places like the SOHC4.net forum, the other two you may have to buy.
2. Evaluate your tools. use the manual to figure out what basic tools you are going to need. There is a thread about my 1975 CB750F that has a massive tool list in it right around page 7, go look for it.
3. Don't modify a thing. The first step to any custom is building off a solid foundation. The bike needs to run well and be rideable and you need to actually ride it before you start modifying it. Chances are once you modify it the first two things you will want to do are brakes and suspension.

Chances are if the bike has been sitting it will need brakes, tires, a fork rebuild, etc....more than just a set of tires and a carb clean. Why not post some pics of it and we can tell you what it needs.

But I'd like eventually overhaul it completely and turn it into a serious Cafe Racer. I figure the carburetor is the best place to start. Since I want it to eventually be a sleek Cafe Racer, I want to tune it for pod filters and performance exhaust. I think I understand the basics of re-jetting the carburetor from some videos I've found on YouTube. But my current knowledge is entry level at best and, depending on the presenter, YouTube isn't always the most reliable source. I'm a bit overwhelmed right now. I've done some Googling and I'm still not sure where/what parts to buy for my exact model of bike. If any of you could point me in the right direction for some good educational reources, I'd really appreciate it! I look forward to interacting with you all over the course of my builds and hope I can eventually learn enough to be of help to others.

This is where your enthusiasm is causing you to be stupid. Something you will learn playing with these bikes are that pod filters are pretty much worthless on SOHC cb750s. Like they actually steal power out of a stock engine. You will also come to find that the stock 4-4 exhaust is very good (albeit heavy) for a stock engine and also somewhat coveted so if you still have the stock pipes, don't hack them up.

The carb is the best place to start for you to learn how to rebuild a carb and get a bike running. I will say that these bikes don't run like fuel injected vehicles and they are somewhat cold natured. The choke is important to their running and often they don't idle until somewhat warmed up. You will need special tools to rebuild it but the manual will cover it. USE ONLY HONDA PARTS in rebuilding the carbs. There are kits like K&L or keyster where the brass parts (jets, etc) aren't exactly to spec and if you get an out of spec needle or seat the carb will never work right. Honestly, unless your brass parts are damaged or severly worn, you can reuse most if not all after cleaning and just need gaskets.

 

[brad black]

Now that 'cafe Racers" are like arse holes in that everyone has one, it's easier to stand out on a stock looking time capsule that is fun to ride as well as cool.

and it'll make all the originals worth a whole lot more in years to come given how many have been sacrificed to the cafe gods.

 

[GLENNpm]

Wow! What a bunch of friendly and supportive fellows. I read you all loud and clear! It sounds like filters are bad news. I'll be running without any filters from now on. Thanks!

 

[Geeto67]

Wow! What a bunch of friendly and supportive fellows. I read you all loud and clear! It sounds like filters are bad news. I'll be running without any filters from now on. Thanks!

cheeky monkey

The interesting thing about the SOHC cb750 is it was developed with all the most advanced techniques at the time. they even built one with a window into the combustion chamber to see the flame front. It was 1960's GP tech in a street bike - cars weren't even that advanced at the time. The stock airbox uses things like laminar airflow and helmholtz resonance to provide perfect fueling. It isn't like a 350 chevy where they just stuck an aircleaner on a quadrajet and called it a day, if you take it apart you'll see rubber velocity stacks inside, this is one of the ealiest uses of something that has become very common on modern sport bikes. the best thing to do is get a K&N replacement inside the stock airbox. there are also ways to modify the airbox to improve it as well. In a SOHC cb750 the filters aren't the restriction - it's the valve size. If you look at the years they ran big valves or high lift/duration cams, they always make significantly more power than the middle years (like the one you have).

 

[GLENNpm]

Woah, Woah, Woah! I'm not sure what you think you're doing, Geeto67, but you just wrote the first post in this thread that didn't insult me. Are you feeling OK? Considering your previous post called me stupid, are you sure my tiny brain can process that vast wealth of superior knowledge? I tell you what. I'm going to start slow. As you all suggested, I should definitely scrap my trash vision that my late grandpa would be angered by because it doesn't line up with this group's own superior vision of what all motorcycles should be without even the slightest bit of adulterous deviation. One thing that has been made abundantly clear is that no real cafe racer has ever or should ever actually have anything about its looks modified since performance is the only thing that matters for these amazing machines that are only 50 years behind current performance technology. I see now that it's only ever acceptable and righteous to use original parts and to maintain a strict stock appearance. Thank you for the enlightenment. I think I'm good to go with most of it. I'm only having a hard time finding leaded gasoline. Fortunately, I happen to have an old pencil sharpener from that same era. I'll make sure to start shaving down all my old no. 2 pencils to use as an additive. What do you recommend as an appropriate mixture?

 

[Andyshep]

Reductio ad absurdum......

It's simple, get it running, ride it, change what you need to make it ride better, make it as pretty as you want without altering how it runs.

 

[woodsman]

Woah, Woah, Woah! I'm not sure what you think you're doing, Geeto67, but you just wrote the first post in this thread that didn't insult me. Are you feeling OK? Considering your previous post called me stupid, are you sure my tiny brain can process that vast wealth of superior knowledge? I tell you what. I'm going to start slow. As you all suggested, I should definitely scrap my trash vision that my late grandpa would be angered by because it doesn't line up with this group's own superior vision of what all motorcycles should be without even the slightest bit of adulterous deviation. One thing that has been made abundantly clear is that no real cafe racer has ever or should ever actually have anything about its looks modified since performance is the only thing that matters for these amazing machines that are only 50 years behind current performance technology. I see now that it's only ever acceptable and righteous to use original parts and to maintain a strict stock appearance. Thank you for the enlightenment. I think I'm good to go with most of it. I'm only having a hard time finding leaded gasoline. Fortunately, I happen to have an old pencil sharpener from that same era. I'll make sure to start shaving down all my old no. 2 pencils to use as an additive. What do you recommend as an appropriate mixture?

Don't be discouraged, just ignore the naysayers. There have been thousands of good vintage bikes rendered useless in the name of "Cafe Builders". With your lack of knowledge, youtube, Pipeburn and a Clymer manual, you too will be able to do it as well.

 

[seanbarney41]

cheeky monkey

The interesting thing about the SOHC cb750 is it was developed with all the most advanced techniques at the time. they even built one with a window into the combustion chamber to see the flame front. It was 1960's GP tech in a street bike - cars weren't even that advanced at the time. The stock airbox uses things like laminar airflow and helmholtz resonance to provide perfect fueling. It isn't like a 350 chevy where they just stuck an aircleaner on a quadrajet and called it a day, if you take it apart you'll see rubber velocity stacks inside, this is one of the ealiest uses of something that has become very common on modern sport bikes. the best thing to do is get a K&N replacement inside the stock airbox. there are also ways to modify the airbox to improve it as well. In a SOHC cb750 the filters aren't the restriction - it's the valve size. If you look at the years they ran big valves or high lift/duration cams, they always make significantly more power than the middle years (like the one you have).

dude, some pretty simple stuff here that you may not have caught onto-
-no one here is going to hold your hand and lavish compliments while you hack up a cb750, so if you need that loving feeling while doing hateful things to some poor old jap bike, go find another site. SOHC4.net has plenty of members that will simply explode with joy while you turn a later day version of the original superbike into an unrideable amalgamation of poor welds, bad design, modern parts that make the bike handle worse, and cheap chinese gizmos that further decrease performance...but hey, as long as some dickhead in Winnipeg, Canada that learned how to wobble down the driveway 3 weeks after you did likes how it looks on the internet, it must be good
-dudes on here (except me an Geeto and god knows who else) really could give 2 fucks about another cb750 because they got real exotic stuff that you will not see like Ducati's, Kaw H2's, Guzzi's, Norton Dominators, Seeley Hondas and the list continues infinitely...thing is they are still nice enough to actually respond to your thread full of ignorance
-all the information you have recieved so far is correct and helpful

so calm down, listen up, take your time and you will learn plenty of valuable knowledge...you have already been told that pod filters do not work well on your bike. Guess what, it's true! Now what the hell is there to be so offended about?

 

[Stephen J]

-all the information you have recieved so far is correct and helpful
so calm down, listen up, take your time and you will learn plenty of valuable knowledge...you have already been told that pod filters do not work well on your bike. Guess what, it's true! Now what the hell is there to be so offended about?

^^^^Yea this^^^^^ Unlike yourself I'll take sound advice (specially if it's free) no matter how it's delivered. You can get all but hurt and fuck off if ya like. No ones feelings here'll be hurt. You'll be cutting yourself off of a huge amount of knowledge though. The internet is no place for thin skin. Good luck either way. Ride safe.

 

[Register]

GLENNpm. Seriously, it’s worth istening.

You should read the shit fest I endured before the predudice/opinions became a font of knowledge.

Endure

 

[Geeto67]

Considering your previous post called me stupid, are you sure my tiny brain can process that vast wealth of superior knowledge?

Assuming you are gone and not reading this anymore, I want to clarify something to others that may be reading this. You can be an intelligent, capable, person and still do stupid things. It happens to all of us all the time and it is usually a product of being ill informed or inexperienced. If someone is saying "hey that thing you are doing is stupid" they are telling you that you didn't think it through enough and you should probably re-think it, do some research, and maybe ask some more questions. If your only take away from that is "he called me stupid" then maybe you should rethink your hobby, maybe don't go into one where you are relying on the knowledge of others to make up for your own in-experience. Either you are here to learn from people or you aren't and if someone is saying "hey that thing you are doing is stupid" maybe you aren't as willing to learn as you thought.

I tell you what. I'm going to start slow. As you all suggested,

Sound Advice.

I should definitely scrap my trash vision

yeah that is probably wise since....you know....you don't actually have either experience or knowledge and most of your vision is likely based off of google images searches rather than trial and error. At the very least you should be flexible with it as you pick up both knowledge and experience. Actually, how much of it is actually YOUR vision, and not the vision of someone else who posted a pic online and whose level of knowledge and experience you don't know? Just because someone did it and there is a picture of it, doesn't mean it's the smart thing to do.

that my late grandpa would be angered by

he's ded right? pretty sure he's not going to get angry at anything. If he is, you probably have more to worry about than a motorcycle, like say...the zombie uprising.

because it doesn't line up with this group's own superior vision of what all motorcycles should be without even the slightest bit of adulterous deviation.

Do you know what that is? or are you just projecting your butt hurt to the logical conclusion to protect your fragile ego? I mean can you tell me what "This group's superior vision" actually looks like? because I can't and apparently I am part of this group. I can tell you that the only vision you talked about were the product of you lack of knowledge and experience because if you had either you'd realize there are alternate ways to modify things that...you know...actually make them better.

One thing that has been made abundantly clear is that no real cafe racer has ever or should ever actually have anything about its looks modified since performance is the only thing that matters for these amazing machines that are only 50 years behind current performance technology. I see now that it's only ever acceptable and righteous to use original parts and to maintain a strict stock appearance. Thank you for the enlightenment. I think I'm good to go with most of it.

Show me where that is abundantly clear. Please, tell me where anybody has said this outright. Honestly I think you are just mad because you came in here with a lot of preconceived notions and are finding out that many of them are not correct. Motorcycles are not universal - the ethos that works for one genre doesn't always work for another. Either you are here to learn or you are here to fight with experienced people about how your inexperienced decisions should be valued. Your lack of experience has no value, nobody thinks less of you because you don't know and want help, they think less of you when you get that help and act like it's an insult somehow.

I'm only having a hard time finding leaded gasoline. Fortunately, I happen to have an old pencil sharpener from that same era. I'll make sure to start shaving down all my old no. 2 pencils to use as an additive. What do you recommend as an appropriate mixture?

Why do you need leaded gasoline? Pro tip: These old hondas run great on regular old US unleaded 83 octane. You don't even need to put in the hi-test or premium fuel unless it is above 80 degrees and you want to stave off detonation. If you are putting lead additive in this bike all you are doing is making small lead pellets that can get trapped in the valves. This is something experience would teach you, or you could have asked someone with experience "hey do I need leaded gas?". Also pencils are graphite and clay now which is not a good substitute for Tetra Ethel Lead in gasoline, this is something that knowledge and research would teach you. I realize you were being snarky and kind of an asshole, but thank you for giving me a good example of how knowledge and experience are valuable and valuing ignorance is not for others to learn from.

I hope you enjoy this hobby at some point, but since you are determined to make bad decisions I don't have a lot of hope that you will. You are always welcome here, whether we thing you are making stupid decision or not.

 

[Jruff5585]

Do what ever your vision is, start with the carbs and rebuild them with what ever parts you want. Don't listen to these guys WTF do they know anyway. I do pretty good buying bikes from visionary's and unfucking them, I do even better when they pay me to unfuck it for them. Youtube to learn how to tune carbs, who knew. If one of my kids or grand-kids fuck with any of the bikes I leave them, I'll come back and haunt their asses.

 

[Devil Cafe]

I'm super new to this whole scene, as it seems you are too. My first post had plenty of snarky comments, and what felt like attacking remarks, but all of the people who commented had legitimate and helpful advice, just look past the sarcasm and stuff, because I'd much prefer to have my entire build view shattered, than to make something unsafe (or more unsafe) that looks "neat." I'm sure whatever you build will be cool because of sentimental value, but don't just ignore these comments, most of these people want you to be safe on a bike that works properly

 

[kenessex]

Ok Sparky, listen up and remember, this forum is not here to help you. That is not why we are her, it is a by product of who we are. We will help you as much as you are willing to accept, but we will do it in our way, not yours. You are not really a special snowflake that should get a participation ribbon from the "cafe racer builder" crowd. If you want affirmations for all of your grandiose and original ideas, go elsewhere. There are forums like that will tell you how great you and your bike are, brother and welcome to the scene/lifestyle. That isn't here! You may be special to somebody, but not us.

Now that I have that off my chest, I will say that Geeto was, in fact, mean when he called you stupid. I can tell you are not stupid by the fact that you can communicate clearly in English and that you have a nice sarcastic wit. You are ignorant as evidenced by your lack of knowledge about your carbs and your argument about pod filters. Ignorant is not a problem as long as you are not stupid to go along with it.

Here is the real answer to what you need to do with your CB750. I have made this list so many times I should just put it in a word document and cut and paste it in every newby thread.
1. Give the engine a complete service. This will include rebuilding the carbs since they are a known problem for you. You are sure they need to be cleaned, don't you? How do you know that?
2. Once the engine is running well, give the rest of the bike a complete service, tires, brakes with new stainless lines and dual discs by adding a disc, caliper and bracket, cables, steering bearings, fork flush with new seals, oil and some progressive suspension springs.
3. replace the rear shocks
4. put on some superbike bars
5. ride the bike for the whole next summer, fixing all of the other stuff which will break, like the brake switches and the fuse box and the starter button, etc...
6. figure out what the bike wants to be and consider things like a different seat, front end, rear sets wheels that will be based on knowledge and experience.

You're welcome.