New to me cb650 custom 1980. Where to start

If it's broken or just needs tweaked

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Jr102893
Posts: 8
Joined: Sat Aug 13, 2016 1:17 pm

New to me cb650 custom 1980. Where to start

Postby Jr102893 » Tue Aug 16, 2016 6:42 pm

Hello, I've just got a running honda cb650 1980 custom and I plan to do a full rebuild over the winter in the mean time I want to fix it just enough to ride it around for the summer. Since this is my first bike I am not sure where to start but here is what I've noticed so far.

On start and idle cylinder 1 does not heat up but it does heat up quickly at riding speeds

Cylinders 1 & 2 smoke lightly but noticably after warming up but do not start smoking until revved

On my first ride from the seller the idle was set too high and the bike began to smoke from the air box half way home It was overheating aswell ( idles well enough now)
The oil filter was installed incorrectly and it was one quarter low on oil.(fixed)

I have preformed a compression test after warming up the results as follows
Cylinder 1 145 dry 175 with oil
Cylinder 2 130 dry 155 with oil
Cylinder 3 120 dry 135 with oil
Cylinder 4 125 dry 145 with oil

I'm not sure where to start I assume it will need a complete upper end rebuild (the clymer manual says this can be preformed in the frame... thoughts?)

Any feedback would be great. Any ideas on what I should do first/will riding it in this condition be detrimental to the engine not really including parts that would be replaced during a rebuild.

Thanks
JR

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Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: New to me cb650 custom 1980. Where to start

Postby Volker_P » Wed Aug 17, 2016 1:35 am

Welcome here! :D

This sounds like an engine that suffered considerably and is not in good shape any more.
So your plan for a full rebuild over winter seems a good one.

My main concern for riding until then is this one:
Jr102893 wrote:The oil filter was installed incorrectly and it was one quarter low on oil.(fixed)

Because if this means the collar was placed over the openings in the oil filter bolt the engine might have suffered considerably.
I would at least remove the valve covers and inspect the rocker arms and camshaft as good as possible from there.
And I would drain the oil and remove the oil pan.
From how it looks in there (filings, sealant?), one might better decide if the engine may survive reasonably further riding until winter.

Good luck!
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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