1981 CB650 beater

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1981 CB650 beater

Postby Guest » Tue May 09, 2006 1:56 pm

Hey everyone,

I am pleased to announce that I just picked up a 1981 CB650 to complement my 81 CB650C. The seller bought it 4 or 5 months ago from a dealer and took it straight to a mechanic. The mechanic told him its not firing on cylinder number 3, and "not pulling oil into the upper part of the engine." When I asked the seller more details, he said, "The mechanic said he could tell by the way he heard it running". So, the seller managed to roll it home and it has been now just sitting for the last few months under a tarp.

Its in pretty rough shape. There is quite a bit of rust and oxidization on all the chrome and the engine, it appears to be leaking oil from the head gasket and from another location that looks to be the valve cover on cylinder 1. I took over a battery and did a quick check on the electrical system. The starter turned the engine over, the head light worked, horn works, blinkers didn't really work, it sounded like the relay was broken. The entire airbox/filter assembly was removed from the carbs, and the rear drum brake is partially dissasembled so I am expecting to be short a few parts.

The good news is that the tank looks to be in good shape, side covers are in good shape, it has a big fairing and hard luggage cases and the rubber is in not bad shape. I am hoping that under all that rust, corrosion, dirt and fairing that there is a decent bike under there waiting to come out.

Anyone have any idea on what the mechanics comments may mean in terms of the oil problem? Does this mean that oil is not getting to the cam shaft/valves? Are there diagnostic tests that can be done to check the oil system?

Attached are some pics. This will probably be my summer project bike, so if anyone has any cool ideas on modifications please pass them on, as I am still throwing several ideas around on things to do (besides get it running of course).

Rob



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Postby rob » Tue May 09, 2006 1:58 pm

Sorry, forgot to login. Do picture posts not work for Guests?

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Rob
'81 CB650 Custom

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Ibsen
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Postby Ibsen » Tue May 09, 2006 2:16 pm

The best way to check the oil feed to the camshaft will be to take off the valve covers and check if there is any oil there. Then turn the engine kill switch to off and crank the engine with the starter. You should see if oil is pumped up to the top of the engine.
An exparienced mechanic should be able to tell if anything is wrong with the camshaft lobes, or the cam bearings, if there is any unusual knocking and rattle from the top of the engine. And since you already have one running 650, you should be able to hear the difference between them.
Did the seller do anything to the engine before he started it btw? If it has been sitting for a periode of time, I would have taken off the oil pan and cleaned the oil pump screen, and changed oil and oil filter as a minimum before the engine was started.

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Postby rob » Tue May 09, 2006 2:27 pm

Thanks for the reply Ibsen. Will cranking the engine over with the valve covers off send oil flying?

We never started the engine, just turned it over for a second with the engine kill switch off. The seller wasn't mechanically inclined and hasn't touched the bike, so I would say that nothing has been done in terms of changing the oil, oil filter, etc. He had another 80 CB650 which was running, but from the condition of the bike I would say that it doesn't get much TLC.

Can taking out the oil pan, cleaning the sceen and everything be done with the engine still in the bike? Or does it require a more involved dissasembly?

I am not bringing the bike home until the weekend, but can't wait to get wrenching..

Rob
'81 CB650 Custom

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Ibsen
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Postby Ibsen » Tue May 09, 2006 3:41 pm

Yes, you can take off the oil pan with the engine in the bike.
Cranking the engine with the valce covers off won't send the oil all over the place. But you should see it flowing.

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Postby Vatch » Tue May 09, 2006 4:27 pm

That one was really set up for some touring. How much did you get it for?

There is a guy over on the SOHC forum parting out a 79 650. He may have some parts you could use.
'99 1500 Drifter

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Postby rob » Tue May 09, 2006 5:53 pm

Yeah, really setup for touring. The fairing even has speakers in it! No stereo though. Are the stereos usually setup to have they're own battery hooked up to the alternator? Or does it just run off the bikes battery? With the combination of wind, motor and full face helment, I think that you'd have to have it cranked pretty good to be able to listen to music.

The latches on the hardcases are iffy at best, so I don't know if they'll work out for me.

I picked it up for $200 USD, a pretty good deal, but again, its in pretty rough shape. I would really like to turn this bike into more of a chopper/bobber and ditch the touring gear, but will probably just set my sights on getting it road worthy first. If I can't get it going after a few months it may just become spare parts for the 81 CB650C I have on the road.

Rob
'81 CB650 Custom

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Vatch
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Postby Vatch » Tue May 09, 2006 7:12 pm

Hard to go wrong for $200!

Sort of looks like the old Honda SilverWings , GL650 or 500 (I can't remember which). A guy I used to know had one. The sound coming from those speakers was not good. He had to blast it to hear anything. Some music sounded better than others out of the speakers. AC/DC - good. Tiffany - bad. :lol:
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Chris
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Postby Chris » Tue May 09, 2006 10:32 pm

Wow, what a bargain!
1980 CB650c

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Re: 1981 CB650 beater

Postby Volker_P » Wed May 10, 2006 1:11 am

Well, when there is a oil leak at the cylinder head, there seems to be oil pressure there. :wink: When you open the valve covers to have a look on the running engine, first check if the camshaft or the rocker arms already started to get blue. In this case you should not run it. To hear special things from the top of the head, valve and tensioner adjustment should be allright.

You can easily find out about not firing cylinders by checking whether an exhaust stays cold.

It is a good idea to remove the oil pan to clean the screen and to check for metal parts. Be prepared that some oil will come out as soon you pull the screen out of its socket! I was not last time :shock:. Check the two O-rings at the screen socket, if both should be damaged, the oil pump may suck air. If you find much stuff on the screen, possibly also the oil filter is plugged what together might be the origin of the mechanic's comment. The oil sump provides a first impression whether the engine is allright from inside or needs to be opened. Anyway, you will have to strip it down at least to the head gasket to replace the two 2.5x5mm O-rings if the head oil leak is severe. That's also possible with the engine in the frame. Clean the head bolts heads carefully for good contact to a 12mm nut to avoid further trouble. Use a small torque wench to fix the 22 6mm head cover screws to avoid thread failure.

All in all, does not look like not a bad buy for 200U$.

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Postby rob » Wed May 17, 2006 1:11 am

Hey everyone,

Just a quick update: got this bike home and have started working on it.

The bad: no brake lever, master cylinder, or reservoir, front caliper sized pretty solidly. Throttle and clutch cables pretty stiff, needs lubing. Chain and sprockets in pretty rough shape, oil pan bolt is stripped. One of the bolts on the cylinder head cover was helicoiled in , so that may be a little bit of a pain. Going to need a new cylinder head cover gasket.

The good: carbs seem in good shape, just a few flecks of rust in the floats. Removed the oil pan to drain the oil as bolt is stripped (god did that ever make a mess). The screen looked pretty good, and there were no metal bits in the oil pan.

Rob
'81 CB650 Custom

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Chris
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Postby Chris » Wed May 17, 2006 9:44 am

Hey Rob. I just saw a complete front brake assembly posted on ebay last night. Here's the link for ya:

http://cgi.ebay.com/ebaymotors/CB650-CB ... dZViewItem

This is the whole thing from the handle/resevoir to the caliper :wink: Personally, I've never bought or sold anything on Ebay, but I might find a way to start buying there considering all the CB650 parts I keep finding. If I had million dollars...
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Postby cb650 » Wed May 17, 2006 8:09 pm

Vatch wrote:Hard to go wrong for $200!

Sort of looks like the old Honda SilverWings , GL650 or 500 (I can't remember which). A guy I used to know had one. The sound coming from those speakers was not good. He had to blast it to hear anything. Some music sounded better than others out of the speakers. AC/DC - good. Tiffany - bad. :lol:

They also made a 500 and 650 turbo on the cx500 platform. The 650 is very rare.



Terry


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