1971 cb350 custom (rolling chassis)

H

hindesjake

New Member
Hey everyone, my name is Jake, im 21 year old mechanical engineering student at a school in Charlotte, NC and this is my first bike build so I might need lots of help. Its a 1971 cb 350. Due to my busy schedule i will most likely only be posting a couple times of week. I hope you enjoy!

The look I will be going for on this bike is a brushed aluminum and semi-gloss black. I will be powdering some of the parts while using duplicolor engine enamel on the others. I will also go through the motor and basically do an "overhaul." My brother is a fabricator and will be making the tank, as well as the fenders. Im looking for other ideas in general, brake light, headlight, electrical, exhaust etc... If you have any ideas just let me know!

Today was my first day of "getting" into the bike. I would consider it a pretty successful day due to the fact of the bike came from being completely ride-able, to all the parts laying on the workbench.

The very first thing i noticed on the bike was the poor electrical wiring job. It had obviously been messed with before. So, that brings me to my first question. I'm eventually going to hide the battery under a brat style seat and i want as little as possible electrical wiring on the bike. What can I do? Can someone try to give me a detailed list of parts that i will need and some type of wiring schematic? Thanks

The next thing I noticed was how minimal the rust was! This made me extremely happy!

Let me know what you think!


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Re: 1971 cb350 cafe build

I also will be selling some odds and ends through here on out. The first is my exhaust and it is in nearly perfect condition. Let me know if interested

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Re: 1971 cb350 cafe build

hindesjake said:
I also will be selling some odds and ends through here on out. The first is my exhaust and it is in nearly perfect condition. Let me know if interested

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Welcome tothe site man, your frame is indeed really clean, glad you found this site. I'm in the Raleigh Durham area. I'm interested in your exhaust pipes, i sent you a PM.
 
Re: 1971 cb350 cafe build

What a great bike to get started with. It already had the Mikuni carbs ad the aftermarket shocks?? Thats awesome, if your ever looking to part with those, let me know!

As the the electrical, im working on a simplified wiring diagram for my '71 CB350 that might come in handy, should be worked out by tomorrow, I'll send you a link.

Keep on it!

bob.
 
Re: 1971 cb350 cafe build

*EDIT* It appears that Photobucket took the resolution and pooped all over it. If you're interested PM me and I'll email you the original PDF file.

Alright, here's what I got. Mind you I havent actually run the wires yet, but according to the original wiring diagrams it works. Also note that its not the stock wiring as I have removed certain things on my bike, but it'll still do the job.

CB350TWiringDiagram.jpg


Direct link to the full size image here: http://i293.photobucket.com/albums/mm60/bobdotdesign/CB350TWiringDiagram.jpg
The image is 12" x 24" true size so it should maintain resolution if you want to print it.

bob.
 
Re: 1971 cb350 cafe build

Bobdot! great job! really well done! thanks again! Now, obviously this is for a non electric start bike. Is the minimum size battery im going to need to run the headlight, brakelight, etc... a 12v? Once again, i'm trying to figure out how to hide this.
 
Re: 1971 cb350 cafe build

Bobdot said:
What a great bike to get started with. It already had the Mikuni carbs ad the aftermarket shocks?? Thats awesome, if your ever looking to part with those, let me know!

As the the electrical, im working on a simplified wiring diagram for my '71 CB350 that might come in handy, should be worked out by tomorrow, I'll send you a link.

Keep on it!

bob.
Click to expand...

Yes it already had the mikuni carbs and aftermarket shocks. Why are the springs on those shocks two different colors? what kind of shocks are they?
 
Re: 1971 cb350 cafe build

Yea, you need a 12V. As for amp hours, I've run a 7.5ah just fine and looking to downsize even more since nicking the elec start. Won't know for sure until I test it out. Look around the site for more answers, i know they're out there.

bob.
 
Re: 1971 cb350 cafe build

The voltage has nothing to do with the capacity of the battery. The cb350 runs on a 12v system, as do most bikes made after the late sixties. Enduro bikes are sometimes exceptions to this. But anyways, the capacity of the battery is measured in amp hours. To run electric start you probably want to be somewhere in the 7.5+ amph range, but don't hold me to that. Just food for thought, I'm successfully running kick start only on a cb350 with just 3.3 amphs... And if you maintain your bike, it really shouldn't take more than a few kicks...
 
Re: 1971 cb350 cafe build

Ok so i think this week im going to try to run the electrical and get all of that straightened out before i start rebuilding, sanding, painting, etc.

Im trying to make this an everyday comfortable driver and hopefully and interstate driver also. I know its not going to be the most comfortable ride ever but thats ok! Are they anyways i can reduce vibration/ increase top speed at high rpms? I know i can reduce the size of the rear sprocket or increase the size of the front sprocket to mess with top speed. What is everyones teeth number they are running on these? whats stock teeth number? etc... And im not sure if the vibration was due to the wheels being out of balance or not. Does everyone have this problem at about 55mph?
 
Re: 1971 cb350 cafe build

All the parallel twins vibrate, but it shouldn't be so bad that you don't want to ride the bike or anything.

The four cylinders of the 750s, 550s and other inline fours don't vibrate as much, because the cylinders are on opposing strokes and counter balance each other. Not sure if that's the best way to put it, but the bottom line is your bike will be have some vibration. It's been a topic of conversation for as long as cafe racers have been around, whether it's a Honda, Triumph, BSA, etc.

I'd love to get my hands on the right inline four, but to me, the vibration is part of the experience.

I can't answer definitively on the sprocket thing, but I <u>believe</u> you would go up in teeth on the front sprocket to increase your top end, but you risk losing some quickness off the line. One thing I'd suggest is replacing both sprockets and chain at the same time, though, to make sure they all wear evenly. From what I understand, going up in teeth on the rear sprocket will bring down your top speed, so keep that in mind when replacing that as well. I'm not sure how many teeth are in your front sprocket.

I've thought about going up a tooth on the front sprocket as well. My bike sits at 6000 in top gear at 60mph. I wouldn't mind having that at 5300 or 5500.

See if you can find a Honda shop manual for that thing online. I'm sure someone has one.
 
Re: 1971 cb350 cafe build

Looking through my honda manual now and can't find any info on sprocket size. BUT, I came accross this site yesterday: http://home.brisnet.com.au/~jmiller/honda/index.html

Says there the stock is 16 (front)/ 36 (rear) and then gives a couple of options for different results. I havent personally messed with my gearing but it's in the plans.

bob.
 
Re: 1971 cb350 cafe build

larger front sprocket = higher top speed, slower acceleration
smaller front sprocket = lower top speed, faster acceleration
larger rear sprocket = lower top speed, faster acceleration
smaller rear sprocket = higher top speed, slower acceleration

1 tooth change (up or down) is roughly equivalent to 3 teeth in the other direction on the rear.

Dividing your rear sprocket # by your front # will give you your final drive ratio.
Example: 36/16= 2.25

One thing to watch out for when changing sprocket is engine case clearance (if going up in the front), and chain/swingarm interference with any significant change front or rear.
 
Re: 1971 cb350 cafe build

atvpyrofreak said:
smaller front sprocket = higher top speed, slower acceleration
larger front sprocket = lower top speed, faster acceleration
smaller rear sprocket = lower top speed, faster acceleration
larger rear sprocket = higher top speed, slower acceleration

1 tooth change (up or down) is roughly equivalent to 3 teeth in the other direction on the rear.

Dividing your rear sprocket # by your front # will give you your final drive ratio.
Example: 36/16= 2.25

One thing to watch out for when changing sprocket is engine case clearance (if going up in the front), and chain/swingarm interference with any significant change front or rear.
Click to expand...

The bold text incorrect. Taller gearing (a relatively smaller rear) produces a higher top speed. Shorter gearing (relatively larger front sprocket) produces faster acceleration. For evidence of this, check out any dirt bike or especially a trials bike. The gearing is very short (big rear sprocket) because they don't care about top speed, instead they need instant power from a stand still to climb over obstacles.
 
Re: 1971 cb350 cafe build

boomshakalaka said:
The bold text incorrect. Taller gearing (a relatively smaller rear) produces a higher top speed. Shorter gearing (relatively larger front sprocket) produces faster acceleration. For evidence of this, check out any dirt bike or especially a trials bike. The gearing is very short (big rear sprocket) because they don't care about top speed, instead they need instant power from a stand still to climb over obstacles.
Click to expand...

AHH!
I think I had a failure to communicate between brain and finger, all 4 were wrong... I blame mental fatigue. I have amended my previous post with the proper information.
 
Re: 1971 cb350 cafe build

atvpyrofreak said:
AHH!
I think I had a failure to communicate between brain and finger, all 4 were wrong... I blame mental fatigue. I have amended my previous post with the proper information.
Click to expand...

no.. the first two are correct. Rear sprocket getting smaller = front sprocket getting bigger. Rear sprocket getting smaller = front sprocket getting bigger.

take a look at this: http://www.sportbikesolutions.com/sprockets_and_gearing.htm
 
Re: 1971 cb350 cafe build

The first two were not correct. What I have posted now is correct. As you stated, For more speed, rear smaller, or front larger. For acceleration, rear larger, or front smaller.

If I had only changed the last two, it would have read: top speed = rear smaller or front smaller. Acceleration = rear larger or front larger. Which is wrong, as there has to be an inverse relationship.
 
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