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We do mostly go fast performance bikes here, slammed suspension and fat tires do not make a motorcycle do anything better. Uber high performance motorcycle tires are available in a very narrow range of sizes. We like things like uber high performance tires way more then big open triangles and bone lines on a steel fuel tank thing.
 

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Hello, all:
I am a Maryland resident currently working on building a cafe racer out of a 1982 CB750K and 1981 CB750C. This is my first build and I'm a new rider, so although I generally work through the process on my own, I'm hoping to use this site to avoid stylistic or mechanical oversights on account of inexperience. I bought the 1981 CB750C first, then bought the 1982 CB750K after realizing it was an easier starting point (confirming what I read on this site).
Hi. Welcome onboard. Some good conversation here about your build. Keep us posted on progress.
 

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You seem like you are genuinely interested in putting together a good bike as opposed to lawn art and that will get you help here. Stop looking at or reading about these dopey Pipeburn POS motorcycles they have nothing to do with putting together a great riding machine. Look up Steveo's Ducati Imola build, it is a good example of how a pro completely changes the cosmetics of the bike and never loses anything that makes the SS a top notch performance motorcycle.

The other thought to keep in mind is when you are riding with a group is often the time when someone will want to try out a bike that another rider owns. As an example if you and I are together, me on my snotty, beat up, little 620 Monster and you on a Pipeburn special, we aren't swapping. Not just because I don't want to ride yours but also because I can see you know nothing about motorcycles and my Monster isn't your clunker. I don't want to find out you can't ride it but think you can.

Your framework is the real issue at this point. Put the wire spoke rims back on with the normal tires. Cut out your hoop. Take one shock off, put a ratchet strap between the seat pan and the swing arm. You should be able to tighten it down until the shock bottoms out. That's the travel you need. There are a couple ways to correct it. Airtech may have a seat pan you could use to cover the structuring.

Shocks, fork internals, tires and braided brake line upgrades would be money well spent. Wear and maintenance issues should be attended to. And then just ride it until you know something about the bike.

Progressive and Hagon are good suspension vendors. You can ask for tire recommendations. If you are a new rider don't go with clip ons, better a superbike bar. You want to be upright and comfortable when you are learning to ride, it's a survival thing. You want to e able to see what is going on around you because you have no muscle memory until you get many miles under your belt.
 

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Yes, LED lights. I thought AGM batteries worked with the stock charging system because they are still lead acid. If not, do you have suggestions on how to update the charging system? Just an aftermarket rectifier, or is it more involved?
Read all this and tell me if it sounds like your old stock motorcycle charging system is going to do the job.
 

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Discussion Starter · #28 ·
Read all this and tell me if it sounds like your old stock motorcycle charging system is going to do the job.
Sounds like overcharging will be an issue. It also sounds like an ill suited charging system will just shorten the lifespan of the battery, not damage the bike. Do you agree?
 

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Discussion Starter · #29 ·
You seem like you are genuinely interested in putting together a good bike as opposed to lawn art and that will get you help here. Stop looking at or reading about these dopey Pipeburn POS motorcycles they have nothing to do with putting together a great riding machine. Look up Steveo's Ducati Imola build, it is a good example of how a pro completely changes the cosmetics of the bike and never loses anything that makes the SS a top notch performance motorcycle.

The other thought to keep in mind is when you are riding with a group is often the time when someone will want to try out a bike that another rider owns. As an example if you and I are together, me on my snotty, beat up, little 620 Monster and you on a Pipeburn special, we aren't swapping. Not just because I don't want to ride yours but also because I can see you know nothing about motorcycles and my Monster isn't your clunker. I don't want to find out you can't ride it but think you can.

Your framework is the real issue at this point. Put the wire spoke rims back on with the normal tires. Cut out your hoop. Take one shock off, put a ratchet strap between the seat pan and the swing arm. You should be able to tighten it down until the shock bottoms out. That's the travel you need. There are a couple ways to correct it. Airtech may have a seat pan you could use to cover the structuring.

Shocks, fork internals, tires and braided brake line upgrades would be money well spent. Wear and maintenance issues should be attended to. And then just ride it until you know something about the bike.

Progressive and Hagon are good suspension vendors. You can ask for tire recommendations. If you are a new rider don't go with clip ons, better a superbike bar. You want to be upright and comfortable when you are learning to ride, it's a survival thing. You want to e able to see what is going on around you because you have no muscle memory until you get many miles under your belt.
I checked out Steveo's Imola build and that is on point, for sure. Are there more pictures somewhere, as I only found the one. So I have two bikes: the build is 1981 and the other is 1982. Although I am swapping parts for the benefit of the 1981, I'm going to keep the 1982 operational and fully address any necessary maintenance and repairs. That being said, I may ride the 1982 until I feel comfortable enough to start transitioning onto the 1981 build. The ratchet strap idea for testing the swing arm is great. I built the cowl (seat pan is still in progress) and don't see myself ditching it because I like how it turned out and want to apply my personal touch, but I can adapt it as necessary based on the swing arm range test.
Also, I mentioned earlier that a buddy thought he heard a motor knock in the CB750K. I have uploaded two videos to YouTube: one of the bike starting and one of a road test. It would be great if I could get some input on if there is a knock or not (hopefully the video upload worked).
 

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The bike starting video sounded like my lawn mower in my headphones haha. The road test seemed pretty smooth:unsure:
 

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I checked out Steveo's Imola build and that is on point, for sure. Are there more pictures somewhere, as I only found the one. So I have two bikes: the build is 1981 and the other is 1982. Although I am swapping parts for the benefit of the 1981, I'm going to keep the 1982 operational and fully address any necessary maintenance and repairs. That being said, I may ride the 1982 until I feel comfortable enough to start transitioning onto the 1981 build. The ratchet strap idea for testing the swing arm is great. I built the cowl (seat pan is still in progress) and don't see myself ditching it because I like how it turned out and want to apply my personal touch, but I can adapt it as necessary based on the swing arm range test.
Also, I mentioned earlier that a buddy thought he heard a motor knock in the CB750K. I have uploaded two videos to YouTube: one of the bike starting and one of a road test. It would be great if I could get some input on if there is a knock or not (hopefully the video upload worked).
It won't pass the ratchet strap test, you don't even need to try it.
Don't know what the cowl is, unless you're talking sleds but, carry on with your personal touching.
 

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It won't pass the ratchet strap test, you don't even need to try it.
Don't know what the cowl is, unless you're talking sleds but, carry on with your personal touching.
Let him try it, how would you know it’s not enough clearance anyway? We all know old eyes aren’t reliable.
Do the suspension test and let us know (y) you Made the cowl?!? Looks real cool for sure. Always a fan of personal touching haha
 

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Also, I mentioned earlier that a buddy thought he heard a motor knock in the CB750K. It would be great if I could get some input on if there is a knock or not (hopefully the video upload worked).
Sounds like typical Honda clutch throw-out bearing noise. Pretty normal. You can replace the bearing - no big deal, but it will come back.

Easiest way to test is to pull the clutch lever - if it goes away or the sound lessens - there's your answer.
 

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Discussion Starter · #34 ·
Sounds like typical Honda clutch throw-out bearing noise. Pretty normal. You can replace the bearing - no big deal, but it will come back.

Easiest way to test is to pull the clutch lever - if it goes away or the sound lessens - there's your answer.
That sounds like it may be the case. When you say "no big deal", are you talking about the level of effort for the work, or are you saying throw-out bearing noise doesn't lead to or indicate issues that should be dealt with?
 

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That sounds like it may be the case. When you say "no big deal", are you talking about the level of effort for the work, or are you saying throw-out bearing noise doesn't lead to or indicate issues that should be dealt with?
I'm basically saying that if you replace the CTB the noise will come back pretty quickly.

Your CTB only needs replacing if you have serious gear change issues.

It was a 'problem' with the Honda 4s for years, but it's only a noise, not necessarily a real problem.

Don't worry about it.

Have your ever heard a Ducati dry clutch? - sound like a hand full of bolts being shaken around in a tin can, and then amplified - they still worked fine.

Address the other issues with the bike, before worrying about this is my opinion..
 

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Discussion Starter · #36 ·
Let him try it, how would you know it’s not enough clearance anyway? We all know old eyes aren’t reliable.
Do the suspension test and let us know (y) you Made the cowl?!? Looks real cool for sure. Always a fan of personal touching haha
Thanks. I know it doesn't look like much, but it was hard for me to create strait lines and get everything smooth and symmetrical. I should have built this later in the project after getting more comfortable with welding, but I didn't so had to use bondo and epoxy to clean up the awful weld job. What I learned is that it is very hard to tell if lines are strait when the surface you are looking down is three different colors.
 

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Discussion Starter · #37 ·
I'm basically saying that if you replace the CTB the noise will come back pretty quickly.

Your CTB only needs replacing if you have serious gear change issues.

It was a 'problem' with the Honda 4s for years, but it's only a noise, not necessarily a real problem.

Don't worry about it.

Have your ever heard a Ducati dry clutch? - sound like a hand full of bolts being shaken around in a tin can, and then amplified - they still worked fine.

Address the other issues with the bike, before worrying about this is my opinion..
Roger that. The motor we are talking about is a 1982 with 23k miles, and I am in the process of deciding whether I want to use that one or the 1981 motor with 43k miles. Nobody noticed this sound in the 1981 motor, but the exhaust system on that bike was screwed up in many ways, so who knows what sounds will come to light once a proper muffler is installed. The 1982 was shifting great so I think I will go with that one based on your input.
 

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.... I should have built this later in the project after getting more comfortable with welding, but I didn't so had to use bondo and epoxy to clean up the awful weld job. ....
So you melted a bunch of bubble gum weld onto the frame with little to no penetration anywhere, and then filled it to make it look decent when in fact it is about as strong as hot melt glue. What's the plan for this bike are you selling it?

What you should have learned is that you don't learn to weld on your motorcycles.
 

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Discussion Starter · #40 ·
So you melted a bunch of bubble gum weld onto the frame with little to no penetration anywhere, and then filled it to make it look decent when in fact it is about as strong as hot melt glue. What's the plan for this bike are you selling it?

What you should have learned is that you don't learn to weld on your motorcycles.
I have not done anything to the frame that could influence structural integrity. I’m talking about welding the cowl together, which is bolted to the frame. I did have to weld small tabs to the frame to bolt the cowl down, but these are positioned outside of load bearing areas.
 
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