My "new" 1980 CB650

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Tue Oct 22, 2019 12:15 am

So my bike sat, I'm sad to say, all of this year. The CB650 had an oil leak from the cylinder head that was a slow seep when I got it, and a mechanic told me how much it would cost to fix it and suggested I just live with it. So I put about 8,000 miles on the bike, filling up the oil whenever it went down, and I was happy.

Until it started spraying oil on my pants leg. Gah. This is why it sat out the riding season... I knew what the fix was going to cost, and I had to save up my pennies to pay for it. I can do a lot of mechanical stuff, but I knew beyond a shadow of a doubt that I had no business taking the top end apart myself.

Week before last I loaded her up and hauled her to Reo's Rides in Kirksville, MO. I'm told Reo is good, and he's just a bit less expensive than Cycle Tech up at Fremont, IA where I got the carbs rebuilt. And he's a lot closer to home, making it less of a production to take the bike there and then retrieve it.

Here's hoping everything goes well!

Image

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GeorgeSweety
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Re: My "new" 1980 CB650

Postby GeorgeSweety » Tue Oct 22, 2019 3:08 am

Nice, hope you get it sorted. I've got to replace the cylinder head, cam and rocker box on mine due to a PO managing to get some crap in the cam bearing face, it has destroyed the cam and both bearing seats. I'm actually looking forward to doing it though :D

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Fri May 08, 2020 1:27 pm

It’s really nice to have the CB650 back in service after doing without it last year. The head gasket repair seems solid, and the repairman changed the plugs while he was at it. I had Reo’s Rides in Kirksville, MO do the work for me, and I couldn’t be happier.

https://www.facebook.com/speedwagon82/

At a literal garage sale (aka a sale in an old automotive garage), I got a pair of Honda turn signals, supposedly from an early '70's CB350. That's what the guy thought anyway. They're smaller than the rear signals on my CB650, but in a very similar style, so I thought they'd look good on the front in place of the cheapos I installed when I pulled the fairing.

Here they are installed:

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Nice, eh? While I had the headlight off and was figuring out the usual installation issues, I noticed that the bike turns off the marker light function when it turns on the blinkers. I realized correctly that I could hook both functions up to the blinkers and they would work fine, even though there’s only one filament in each. What I failed to understand is that the marker light voltage would go the “wrong” way back toward the blinker circuits, making the rear signals into marker lights and keeping the turn signal idiot lights on solid when the blinkers are not engaged.

I had a similar problem with a DIY model rocket launch system a few years ago; arming one of the four launch positions would light up all the arming indicator lights, due to voltage going the “wrong” way through the circuit. The solution was obvious… I needed a diode in each arming switch circuit, ensuring that the voltage only went the way I wanted it to go. That answer worked here as well… a diode in each line between a turn signal output connector and the matching front turn signal allows the blinking voltage to go where it’s supposed to, while blocking the marker light voltage from going the wrong way down that wire.

Looking through Amazon’s listing, I found these:

https://www.amazon.com/gp/product/B01CXOQMJ8/

They say they are for solar cells; the main thing is, they are rated for 15 amps, ensuring they have plenty of capacity for my purposes. Better yet, the 20 pack cost me less than $7.00 US.

A smart man, one who knew he needed diodes in the first place, would have incorporated them into the Y adapter. I’m not that smart, obviously. So I decided to just put bullet connectors at the ends and put it between the Y connector and the blinker output connector, inside the headlight. Here's what they look like fully assembled:

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To make an unnecessarily long story short, they work great, though I do notice some fluctuation in the marker lights at idle.

Another annoyance on the CB650 was the kickstand; the tang you’re supposed to push with your foot to lower and raise the kickstand. You see, the original broke off a couple of years ago, just before I benched the bike because of the head gasket leak. So I got this:

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It's not the Kuryakn part, it's the Krator; probably the Kuryakn would have been worth the money. This wasn't.

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A picture, as they say, is worth a thousand words. That bend came from pressing down on the tip of the extension with the edge of my rubber-soled sneaker. What a disappointment.

So I dug around my shop and found a piece of 3/16″ thick, 1″ wide steel bar, got out my grinders (one with a cutting wheel, the other with a grinding wheel), and with the added assistance of my bench vice I made this:

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I didn’t take a picture of it folded up, but it tucks nicely up under the exhaust with just a bit sticking out for my shoe to catch. And it’s a lot thicker and stiffer than the Krator part. Honestly, I cannot recommend that item to anyone… it’s just not strong enough.

Finally, I changed the bars on my 1980 CB650 to a set of CB750K replicas; they are lower, straighter, and a bit wider than the stock bars. I knew I liked them on my 1980 Yamaha XS650, but the "wheelbarrow" handlebars that came on that bike were so bad that anything would be an improvement. What I did not expect is what a difference they'd make on the Honda. It feels like a different bike... the small change to the riding position not only makes it feel more surefooted, but amazingly made the seat more comfortable.

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And that's all, for now.

I should mention that additional details of this project are on my blog here: https://dream.gonnerman.org

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Sun May 30, 2021 5:40 pm

I got the 1980 CB650 out one time earlier this year. It was, as always, a struggle to get it started after it sat for about two months, and I vowed to keep starting it every few days to avoid the battle in the future. I had replaced the front tire with a Bridgestone Spitfire S11F 100/90H-19 in place of the discontinued Bridgestone Battlax BT45 I've been running. I hope the BT46 model is as good, since I still intend to run it on the rear. I did pinch the new tube (gah) and rather than patch it I bought a heavy duty Kenda tube instead.

So as I say, I took the CB650 for a nice 20+ mile ride, one of my local ridge loops, and was pretty happy. Until the next day when I saw an oil spot under the bike. I wasn’t 100% sure the oil was from that bike, so I got a flattened-out cardboard box and parked the bike on it to be sure.

Yup. Oil leak.

Lying down on the box, I could see that the bike seemed to be leaking around the edge of the sump. Another bad gasket, I assumed, and I started making plans to get a new one and get it installed.

Then I remembered how I quelled the top-end oil leak of my Yamaha XS650 by retorquing the head. I decided to try retorquing the sump bolts, but to do that I needed to know the torque specs. Honda, it seems, did not publish torque specs for the sump bolts. Gah, again.

The slightly larger bolts securing the sump plate to the XS650 had a 7 ft-lb spec, I noticed; so I set my torque wrench for 5 ft-lbs and retorqued the Honda’s sump bolts, starting with the one in the middle of the left side and working out, in alternation, first one more in front, then one more in back, and so on until I had readjusted the entire left side to that torque. I decided, based on where I saw oil on the sump, to stop there rather than going on around, and maybe later I’ll regret that. Who knows?

What I do know is, I took the bike out for another similar loop and parked it over a fresh clean white paper towel. So far, after about four days, no signs of further leakage. Keeping my fingers crossed…
Last edited by Solomoriah on Thu May 19, 2022 9:00 pm, edited 1 time in total.

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Wed Jun 09, 2021 9:27 pm

So, story time.

I pulled my bike out to run some errands, and while I was out I filled up with gas. It's about 3 miles from the FS station where I filled up back home, and I came home without incident and parked the bike for about an hour. I was planning to ride it about 25 miles to see a customer, and so about an hour later I started it up and took off.

I went about another 3 miles or so, and the bike died like it ran out of fuel. I rolled into a driveway and tried to restart it, and while the bike was cranking good and hard it wouldn't go. It really did sound like it was out of gas, so I flipped the petcock to reserve, and it started up after a very little bit of cranking.

I turned it back from reserve to "run" or whatever you call it, and rode back home and parked it without difficulty.

I'm guessing something plugged the upper end of the petcock tube, and flipping it to reserve and then back must have cleared it. But now I'm nervous, and very much open to suggestions about how I should proceed.

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Volker_P
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Re: My "new" 1980 CB650

Postby Volker_P » Fri Jun 11, 2021 2:04 am

The petcock has a filter screen that is too coarse to avoid idle issues but fine enough to get clogged with time.
You may pull the fuel line from the carbs and leave some fuel running into a jar to see how much fuel is coming out at the different petcock positions before you consider to remove the petcock for inspection.

Also worth to try this with and without the tank cap, i.e. let it run for a while with a full tank and closed cap and see if flow decreases with time and becomes more again as soon as you open the cap. In this case it would be time to check out the vent in the tank cap.

Interesting turn signal solution. You need to know that this is not stock. Makes the bike look more "classic" :) .
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Fri Jun 11, 2021 8:15 am

Volker_P wrote:The petcock has a filter screen that is too coarse to avoid idle issues but fine enough to get clogged with time.
You may pull the fuel line from the carbs and leave some fuel running into a jar to see how much fuel is coming out at the different petcock positions before you consider to remove the petcock for inspection.

Also worth to try this with and without the tank cap, i.e. let it run for a while with a full tank and closed cap and see if flow decreases with time and becomes more again as soon as you open the cap. In this case it would be time to check out the vent in the tank cap.

Thanks for the suggestions.

I asked on Facebook and got a lot of answers; many were screwy, or obviously only read part of my post. Par for the course for Facebook. But based on my experience and the less useless suggestions there, I rode a short loop (20 miles) where I knew I could get a rescue from my wife, and had no problems; I got bold then and ran a longer loop, 50 miles through roads my wife is not as familiar with, and again had no problems.

I'm guessing that whatever blocked the petcock either fell off in the tank or got sucked through to the inline fuel filter (probably a mod by the original owner, based on prior experience). It looks just like the K&N filter, so I've ordered one of those and plan to replace it.

Volker_P wrote:Interesting turn signal solution. You need to know that this is not stock. Makes the bike look more "classic" :) .

Well aware it isn't stock. I'm honestly perfectly happy with the aftermarket headlight and '70's rear signals on the front... looks "good enough" and it is my daily rider.

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Thu May 19, 2022 10:07 pm

The sump oil leak was still ongoing when I rolled the CB650 out of the garage for the first time today. I reviewed the shop manual and found the torque specs I had previously missed: 7-10 foot-pounds for the M6 bolts in the crankcase area, which is obviously higher than the 5 lbs. torque than I used before. So I retorqued the suspect bolt and the two next to it after running the bike enough to get it up to operating temperature. We'll see, but I'm afraid I will be dropping the sump to put in a new gasket after all. The bike is about due for an oil change, so I won't be wasting the oil I dump out of it.

I have to say, it felt really good riding it the 3 miles down to the FS to fill it up with fresh gas.

I will be replacing the back tire soon; however, this is presenting a problem. The last time I replaced the back tire, I put on a Bridgestone Battlax BT-45 130/80H-17; I got the tubeless model by mistake, but got it mounted with some difficulty (with a tube, of course) and all has been well up to now. Previous research indicated that the "correct" size is 120/90-17, but you just cannot buy a rear tire in that size anywhere anymore. The 130/80-17 size I've been running is nominally 104mm tall, while the 120/90 would be 108mm. 130/90-17 tires do exist, but they would be 117mm tall, 9mm or almost 3/8 of an inch more than the 120/90 and 13mm or right at half an inch taller than what I've got on the bike now.

I should say, 130/90-17 tires do exist, if you can get them. They seem to be out of stock everywhere.

I can run the tire I have for a while yet, but I'm open to suggestions here.
Last edited by Solomoriah on Sat May 21, 2022 11:42 pm, edited 1 time in total.

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Thu May 19, 2022 10:10 pm

Okay, so I just found out that the BT46 Bridgestone is available in the 130/80H-17 tubeless style from Chaparral (or at least, it doesn't SAY it's out of stock). So that may be my solution.

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Volker_P
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Re: My "new" 1980 CB650

Postby Volker_P » Fri May 20, 2022 2:43 am

I do not know for the 17" rear hub but for 130/90-16 tire width is the crucial factor. There is even a cutout in the chain guard as dimensions are very close there. Width variations between manufacturers or tube type vs. tubeless tires might play a role in this case so have a look.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Fri May 20, 2022 11:54 pm

Huh. The Bridgestone 130/80-17 isn't really all that close on the sides at all. I was/am mostly worried about the extra height of the 130/90-17.

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Sat May 21, 2022 10:14 am

Okay, this is going to sound a bit weird, but... I'm now strongly considering the Kenda K761 dual sport tires. They are 80/20 tires, and look rather a lot like some of the other modern street tires, just with wider grooves/sipes. But they are available in tube type for the front and rear of the CB650, with basically the same speed and load rating on the rear as with the Bridgestone Battlax I've been running, and a bit less load index on the front than the Bridgestone Spitfire I have on the front. And they are much cheaper. They may wear faster, I don't know, but honestly I may go for the short-term savings over the long-term lifespan in this case.
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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Sat May 21, 2022 11:47 pm

And, a note on that last bit... the Kenda K761 is not available in "tube type" after all. The site I found those specs on was incorrect, it seems; Kenda's own list says they are all tubeless.

https://powersports.kendatire.com/en-us ... ual-sport/

This does not trouble me in the least, as the tire I'm about to wear out is a tubeless tire with a tube in it (a heavy-duty Kenda tube, actually).

I'm also considering another Kenda dual sport tire, the "Big Block Paver" K678. Like the K761, it's officially an 80/20 tubeless adventure tire. Choosing between the two is, for me, a matter of availability and cost when I actually place the order, so only time will tell.

That latter tire is detailed here:

https://powersports.kendatire.com/en-us ... ock-paver/

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Solomoriah
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Re: My "new" 1980 CB650

Postby Solomoriah » Sun May 22, 2022 4:20 pm

Okay, so go ahead and call me nuts, but I just ordered a Kenda Big Block Paver 130/80-17. We'll see how it works out.
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Old_German
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Re: My "new" 1980 CB650

Postby Old_German » Mon Jun 20, 2022 5:27 pm

Your bike has very nice wheels . . .
Honda did not sell these in Germany.
I did hard work to switch my wheels to spoke wire.

With Greetings from Cologne


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