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Author Topic: 81 CB650C build and introduction  (Read 1843 times)

Offline Bcon615

  • Posts: 10
81 CB650C build and introduction
« on: May 04, 2016, 17:00:08 »
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:




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:

 


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.



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!

81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2317
Re: 81 CB650C build and introduction
« Reply #1 on: May 04, 2016, 17:10:40 »
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
1978 CX650 Super Deluxe
1979 XS1100 Special
1980 XS650
1980 cx500  The Beast
1983 GL650 i
1983 cx650 Custom
1973 CB450
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1977  gl1000
1976 gl1000 LTD
 1983 GL1100 Nekid
and a bunch of others

Offline Bcon615

  • Posts: 10
Re: 81 CB650C build and introduction
« Reply #2 on: May 04, 2016, 17:17:44 »
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?
81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F

Online coyote13

  • Posts: 1139
Re: 81 CB650C build and introduction
« Reply #3 on: May 04, 2016, 17:46:26 »
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.
Half the fun's in the get there...

Offline Bcon615

  • Posts: 10
Re: 81 CB650C build and introduction
« Reply #4 on: May 04, 2016, 17:57:13 »
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
81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2317
Re: 81 CB650C build and introduction
« Reply #5 on: May 04, 2016, 21:04:32 »
does the motor turn if you pull the plugs

and put it in gear and rock the bike forward?
1978 CX650 Super Deluxe
1979 XS1100 Special
1980 XS650
1980 cx500  The Beast
1983 GL650 i
1983 cx650 Custom
1973 CB450
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1977  gl1000
1976 gl1000 LTD
 1983 GL1100 Nekid
and a bunch of others

Offline Psycrow

  • Posts: 78
Re: 81 CB650C build and introduction
« Reply #6 on: Jun 14, 2016, 12:41:52 »
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

Offline Bcon615

  • Posts: 10
Re: 81 CB650C build and introduction
« Reply #7 on: Aug 08, 2016, 10:02:35 »
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
81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F

Offline hillsy

  • Posts: 4094
Re: 81 CB650C build and introduction
« Reply #8 on: Aug 08, 2016, 21:24:44 »
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.

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.

Or just bite the bullet and re-build the engine (the best option in the long run).

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.

Offline Bcon615

  • Posts: 10
Re: 81 CB650C build and introduction
« Reply #9 on: Aug 21, 2016, 12:32:22 »
Welp the engine is out...



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



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 :)



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.





Sent from my iPhone using Tapatalk
81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F

Offline Psycrow

  • Posts: 78
Re: 81 CB650C build and introduction
« Reply #10 on: Aug 21, 2016, 16:53:33 »
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

Sent from my SM-G903W using Tapatalk


Offline Bcon615

  • Posts: 10
Re: 81 CB650C build and introduction
« Reply #11 on: Aug 30, 2016, 12:59:43 »
Time for an update...



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

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.



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



The piston rings are pinched tight in their grooves:



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



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


81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F

Offline AimlessMoto

  • Posts: 150
  • Blood, sweat and beers.
Re: 81 CB650C build and introduction
« Reply #12 on: Aug 30, 2016, 21:29:00 »
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.

Offline Bcon615

  • Posts: 10
Re: 81 CB650C build and introduction
« Reply #13 on: Jul 11, 2017, 23:12:52 »
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



Sent from my iPhone using DO THE TON
81 Honda CB650C
78 Yamaha XS400
76 Kawasaki KZ400
03 Yamaha YZ450F