Newbie with a few questions

If it's broken or just needs tweaked

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Markk71
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Joined: Sun Jul 19, 2015 7:25 pm

Newbie with a few questions

Postby Markk71 » Sun Jul 19, 2015 7:38 pm

Hello and good day!

Brand new to the forum with the recent purchase of a beautiful 1980 CB 650 (couldn't pass up the great deal) Little history to the bike, it sat for 4 years and owner said it didnt run but had drained fuel before storage.

Put gas and new battery and fired right up. Now onto a few issues, i changed my oil to a Motul oil he had provided but will switch to Rotella (run in my motocross bikes and love it) The clutch currently slips a bit when you grease on the throttle at high speeds. I have seen a few threads in regards to adjusting it so not to concerned until I tackle that

Now the way it runs and starts is honestly excellent. Right up untill 6500/ 7000 rpm and it pukes its guts unless you role nicely onto the throttle, It has pod filters currently. And when it is at idle and only low rpm when its warm its making an odd clunking noise that does not go away with the engagement of my clutch. Any ideas on this?

I should add that the clunking noise is quite faint but is noticeable. Maybe timing chain? Or is this a normal sound and I should quit worrying.

Thanks in advance for your help!

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tario
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Re: Newbie with a few questions

Postby tario » Mon Jul 20, 2015 2:43 pm

The noise could be cam chain tension. There is a nut on the back of the engine you loosen then tighten and it fixes itself. My 79 has a similar sound to what you describe. After some research I found that these engines have some noise that can't be helped. It's hard to figure out how much is too much noise on the internet though.

The pod filters could be connected to your problems at high rpms. Possibly incorrectly sized main jets. Does it run lean or rich? Have the carbs been cleaned? Dirty carbs cause lots of problems too.
1979 cb650
1980 cb650

cb650
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Re: Newbie with a few questions

Postby cb650 » Mon Jul 20, 2015 4:01 pm

The clunking is most likely your clutch. If its slipping why not adjust it?
It will make some noise anyway.
Did you clean the tank out?!?!?!?!

Markk71
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Joined: Sun Jul 19, 2015 7:25 pm

Re: Newbie with a few questions

Postby Markk71 » Mon Jul 20, 2015 9:17 pm

So i tinkered quickly with the cam chain tensioner, wondering how exactly does it tighten itself? I did what you said @tario and its still making the same noises. I made a quick video which illustrates the sound quite well. Maybe I am just over reacting? The bike runs well and no vibrations coming from it, its quite smooth from idle to high rpms

I havent gotten to far with the carburetors but i have disassembled them once and they were nearly spotless. It has a K&N inline fuel filter on it, ill browse around for jetting ideas, seen some great threads in regards to jetting the pod filters.

Ill try playing with the clutch this week as well and see if it helps

Here is the video

https://www.youtube.com/watch?v=8BvMmfalb5s

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Folsoml
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Re: Newbie with a few questions

Postby Folsoml » Tue Jul 21, 2015 7:40 am

Markk71 wrote:So i tinkered quickly with the cam chain tensioner, wondering how exactly does it tighten itself?


Picture this, but ignore all the text in the image:

Image

The tensioner would be where the picture reads "push here" and would be spring loaded. When the tensioner nut is tight, it is held in place, and is not under spring power. As your engine wears, the cam chain can get stretched. When you adjust it, you are turning the bottom sprocket counter-clockwise. This tightens the chain on the opposite side of the tensioner, and puts all the slack on the tensioner side. When you release the tensioner nut, the spring pushes the tensioner against the chain and takes up all the slack. You then tighten the nut and it holds the tensioner in this position.

Disclaimer: This illustration is just one that I found in a google search. It is not intended to show how to adjust the cam chain tension on a CB650, but only to give an idea of how a cam chain tensioner works.

PS: Your link to your video shows it is private.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

Markk71
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Joined: Sun Jul 19, 2015 7:25 pm

Re: Newbie with a few questions

Postby Markk71 » Tue Jul 21, 2015 12:46 pm

That was a great explanation. I ran the bike at idle power and loosened it off maybe two turns and I could hear the cam chain tensioner make a bit of noise which has canceled that out as an option. Thank goodness.

Now I'm positive it is coming from the clutch, I have set the video to public and if you could give it a listen and give some feedback that would be great ! It's only 14 or so seconds long.

Markk71
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Re: Newbie with a few questions

Postby Markk71 » Thu Jul 23, 2015 9:39 am

So I've dug a little deeper into the noise. I've drained the oil only to find a particle or two of ferrous material. (Which seems like it could be normal due to the fact that of the bikes age? ) regardless they were very small.

So I pulled the clutch apart to see if maybe my basket was loose with the hub, there was some play there but no indications of grooving or bad wear.

I pulled the oil pan off which had no indication of wear anywhere either aside from one sliver of ferrous material in the screen about half inch in length. With no background on when the last time this has been checked I'm uncertain this is any indication either. The bike has 52xxx on the drive train. So lastly I'm beginning to believe it could be the connecting rods and or crank? I've checked all the valves and they are all within limits. Anybody have any ideas?

Any feedback would be great by this point
https://www.youtube.com/watch?v=8BvMmfalb5s

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tario
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Re: Newbie with a few questions

Postby tario » Thu Jul 23, 2015 7:22 pm

Did you set the valves yet? I hear they go on SOHC's pretty often. Just involves adjusting 8 screws under some covers if your not familiar with the procedure. You'll need a set of feeler guages. I think they were .004 and .003 for intake/exhaust ... or the opposite... check in a manual. Some of the noise at low rpm is normal. Hopefully someone with a bit more experience than me can weigh in on this. I just started a few months ago...
1979 cb650
1980 cb650

AndrewCB650
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Re: Newbie with a few questions

Postby AndrewCB650 » Mon Sep 19, 2016 5:59 pm

I have the same noise on my '81, does anyone else have any insight to this noise and a resolution? Thanks!


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