81 CB650C build and introduction

Bcon615

New Member
Hello everyone, been a member here for a little over a year just reading and learning. However, with the weather warming up I finally took the plunge and bought my first project. A 1981 Honda CB650C for $700. Also, I want to start this build thread because I'm hoping it will motivate me to take more pictures and track my progress.

Here's a picture from when I bought it so we can all bask in its tankless glory:

TkAav4i.jpg



Beautiful isn't she? I put a fresh battery in it and all the lights, signals, and horn work just fine. Now, time for what's wrong...won't start. Whenever I try and start it, you can hear the relay click. I've checked the battery and I'm getting 12V, and I've also removed the starter and tested it with a battery charger and it seems to be working fine as well. Through researching online it seems that the problem could be the starter clutch? So I have purchased a starter clutch repair kit that comes with: springs, spring caps, and rollers. I also bought a replacement starter relay and solenoid because it's inexpensive and why not. I will be away for the next two weeks though because of military obligations, but plan on taking lots of pictures and making some video tutorials as well when I get back.


Right now here is the current state of the bike:

KqsuVwb.jpg



Just removed the sissy bar and that chrome highway foot rest thingy. The tank is actually off of a 1981 Honda CM200. It's just sitting on the bike for the time being. I bought the POR-15 tank sealer kit and will be doing that soon as well. Not sure if I will be sticking with that tank or if it is even possible to mount on that frame without heavy modifications, but right now I am more concerned with having a running, legal, and registered bike. I know very little about tank mounting and fabrication so I will address this issue later once I know more.


Here is a quick photo of my inspiration bike, but I want a matte/flat black gas tank.

eF5frLR.jpg


I learned about these bikes having that "step-up" in the frame back by the seat after I had already bought it and how it can sometimes be challenging to get a good line and have a nice looking seat. But this bike above gives me a lot of hope and motivation!

That's all for now, look forward to hearing from you guys and being apart of this community!
 
its not your starter clutch so dont mess with it

if it were your starter clutch you would here the starter whirr and spin but not engage

so its either your starter or you starter solenoid

try jumping the contacts on the solenoid with a screwdriver

MAKE SURE THE BIKE IS ON THE STAND AND IN NEUTRAL

wear safety glasses as this will create a spark when you jump the terminal

if the starter is good then the motor will crank over
 
cxman said:
its not your starter clutch so dont mess with it

if it were your starter clutch you would here the starter whirr and spin but not engage

so its either your starter or you starter solenoid

try jumping the contacts on the solenoid with a screwdriver

MAKE SURE THE BIKE IS ON THE STAND AND IN NEUTRAL

wear safety glasses as this will create a spark when you jump the terminal

if the starter is good then the motor will crank over

Thanks man! The starter actually does whirr and spin but it is only for a split second. Even if I continue to press and hold the start button. I'm not sure if that is typical or a sign of a bad starter?
 
Make sure that "fresh battery" is actually fully charged and holding. Also make sure it has as many or more cranking amps than the stock battery.
 
coyote13 said:
Make sure that "fresh battery" is actually fully charged and holding. Also make sure it has as many or more cranking amps than the stock battery.

I didn't even think about cranking amps. I'm reading 12V on the terminals with an ohmmeter. I even tried using the battery from my R6 and still no luck. But I will look into the cranking amps of the battery and requirements. Thank you
 
does the motor turn if you pull the plugs

and put it in gear and rock the bike forward?
 
Like above make sure the motor turns over. Put it in 5th gear and see if you can get the motor to turn over. If it's good and your sure the started is trying to go next I would pull the starter for a good cleaning and inspection.

Sent from my SM-G903W using Tapatalk

Psy
 
cxman said:
does the motor turn if you pull the plugs

and put it in gear and rock the bike forward?

Finally had some time to work on the CB650C, been busy trying to buy my first house and put together a YZ450F engine. So I pulled the plugs and tried rocking the bike back and forth, and no luck. Is there a way to manually crank the motor? Also, it seems the transmission is only willing to go from 1st to Neutral and vice versa, not sure if this is typical? Also, got some new handlebars, grips, brake lights and tail lights. Will post progress pictures soon!

- Thanks guys,
Bill
 
[font=verdana, arial, helvetica, sans-serif]If you take the cover off the front rhs of the engine there should be a bolt with a larger nut behind it. Use a socket on the larger nut to rotate the engine.[/font]

[font=verdana, arial, helvetica, sans-serif]HOWEVER.....if you cant move the bike when it's in 5th with the plugs out it's seized. You should use some PB Blaster or something similar to squirt into the cylinders to try and free them up. Be patient, this will take time.[/font]

[font=verdana, arial, helvetica, sans-serif]Or just bite the bullet and re-build the engine (the best option in the long run).[/font]

[font=verdana, arial, helvetica, sans-serif]BTW - the gearbox needs to "move" to shift between gears. With the bike on the centrestand, move the back wheel and the shifter at the same time. You should be able to shift through all the gears this way. [/font]
 
Welp the engine is out...

2dc73b78f4cc076f5bd50c20b1d2e17e.jpg


At least now this will give me an opportunity to paint the frame. Also was able to get the grips and handlebar installed.

44e2b981494896f005bbefc6bd2cd919.jpg


I ordered a gasket set and piston rings so until they get here I am just taking apart the engine, then cleaning and painting all the covers. Put a breaker bar on the bolt in the middle of the alternator and still no luck. Which wouldn't be a big deal since I already have the engine out and planned on replacing the rings, but because of the engine being seized I wasn't able to rotate the camshaft to get the second bolt off of the cam sprocket. So unfortunately I had to cut the chain. So if anyone knows where I can get a replacement chain it would be greatly appreciated!

Also made my first attempt at an electrolysis tub :)

6e89938f206f284b1cb1081b6afbf546.jpg


It worked decently on the rear fender, although I didn't add any washing soda, but it still worked well enough that it probably saved me hours of cleaning and sanding.





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try http://www.partsnmore.com/ for a cam chain and some other bits Mother Honda may have discontinued however many of the stuff you need may still be available OEM from the dealer.

Psy

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Time for an update...

yQeUtPl.jpg


Put the shocks on and just laid the seat on the frame since I haven't started modifying that yet :eek:

Once I was able to get the cylinder jug off (which took hours) I think I have found what was causing the engine to be seized up.

benLATe.jpg


The next two pictures are from the piston closest in the previous picture:

2IAAH6v.jpg


The piston rings are pinched tight in their grooves:

qXp3UoN.jpg


On a better note, I'm really happy with the way painting the engine is going!

C6NRcW0.jpg


Now looking into the future, this bike still does not have a gas tank. So I was wondering, will a 79 CB650 tank fit on my 81 CB650C?


- Bill
 
Soak that piston in ATF or Marvel Mystery oil for a couple days... the rings should pop right out.

As for the cylinder, a mild hone will take care of most of the crud... hopefully it's not pitted.
 
AimlessMoto said:
Soak that piston in ATF or Marvel Mystery oil for a couple days... the rings should pop right out.

As for the cylinder, a mild hone will take care of most of the crud... hopefully it's not pitted.

So I was looking back at this old post, and was shocked when I saw "Aimless Moto". You're the guy with the KZ400 on YouTube!!!!!
I'm currently working on a '76 KZ400 and you're bike is 100% my inspiration (I even bought that same seat cover haha). But yeah, this CB650C project is on hold until the Kawi is finished.
- Cheers dude



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