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by Volker_P
Wed Sep 07, 2016 12:35 am
Forum: General Discussion
Topic: PLUG B, OIL PATH CB650 1979 (Z)
Replies: 3
Views: 1528

Re: PLUG B, OIL PATH CB650 1979 (Z)

Heat usually is a good idea but be careful there. Especially if there should be traces of "ground contact" at the bottom.
Possibly worth to consider if you really need to have it out.
by Volker_P
Tue Sep 06, 2016 1:24 am
Forum: Technical Discussion
Topic: Solution to Not running on 1 or 4 Cylinder + ticking sound
Replies: 1
Views: 794

Re: Solution to Not running on 1 or 4 Cylinder + ticking sound

Yes, tricky issue.
Because everything looks fine as soon as you remove the cover to check out.
Good you found it before you tore everything apart. :)
by Volker_P
Fri Sep 02, 2016 1:03 am
Forum: Technical Discussion
Topic: 80s cb650 c tuning and potential rejeting?
Replies: 1
Views: 878

Re: 80s cb650 c tuning and potential rejeting?

It runs and idles very quietly though it takes maybe 30 seconds and a rev or two for cylinder 1 to start firing and heat up noted by a slight backfire pop on cylinder one as the throttle is letting off. It also smokes less now. 30s until it runs at all four is all right. Do not worry. The only prob...
by Volker_P
Fri Sep 02, 2016 12:44 am
Forum: Technical Discussion
Topic: 1979 CB650 tail light
Replies: 6
Views: 1565

Re: 1979 CB650 tail light

Here is a question I have: If the brown wire associated with the tail light when the bike is running has power coming out of the ignition switch but a break at some later point, could I just splice that wire with the other brown wire? From my understanding of the the US model tail light circuit the...
by Volker_P
Thu Sep 01, 2016 1:01 am
Forum: Technical Discussion
Topic: 1979 CB650 tail light
Replies: 6
Views: 1565

Re: 1979 CB650 tail light

The brown cables are the power supply for the tail light. And e.g. for German bikes there is also a small 3Watts bulb in the headlight for the front parking light. This might explain no second cable comes out from your harness (US model assumed). Here are some hints how to get into the ignition swit...
by Volker_P
Fri Aug 26, 2016 12:39 am
Forum: Technical Discussion
Topic: Throttle butterflies dont retract?
Replies: 5
Views: 1532

Re: Throttle butterflies dont retract?

You are right, I mixed that up.
It has been three years now that my CB is gone and obviously I start to forget some things with time.
Or in other words: I'm getting old! :lol:
by Volker_P
Thu Aug 25, 2016 1:54 am
Forum: General Discussion
Topic: PLUG B, OIL PATH CB650 1979 (Z)
Replies: 3
Views: 1528

Re: PLUG B, OIL PATH CB650 1979 (Z)

I think you should get it out with a 12mm Allen key. You may make a tiny steel plate to shim a possible gap so you get it out safe without damage. It should come out easily, it is just a plug with an O-ring. At least I don't remember trouble there. I won't be surprised if it already would come out w...
by Volker_P
Thu Aug 25, 2016 1:47 am
Forum: General Discussion
Topic: Cylinder Head Temps
Replies: 8
Views: 2250

Re: Cylinder Head Temps

Despite the millions of online horror stories, I think my next move will be to switch to amsoil 10w-40 synthetic metric motorcycle oil. If you know your engine is clean inside (e.g. after you did a complete rebuild) no real problem. But synthetic oil may dissolve all the stuff from decades more or ...
by Volker_P
Thu Aug 25, 2016 1:23 am
Forum: Bikes
Topic: CB650 Custom
Replies: 3
Views: 1595

Re: CB650 Custom

Quite good shape for a daily use bike in the UK!
Interestingly this seems to be a US model. The European 1980 Custom had double disk front from the beginning on.
Stock rear sprocket. :)
Interesting exhaust, don't remember I ever saw this one.
by Volker_P
Thu Aug 25, 2016 1:11 am
Forum: Technical Discussion
Topic: Engine
Replies: 8
Views: 2288

Re: Engine

You can figure out for every part yourself for the most Hondas (and also other brands if you click up one level) at: http://www.partzilla.com/parts/search/Honda/parts.html You find the CB650 head cover at: http://www.partzilla.com/parts/search/Honda/Motorcycle/1980/CB650+A/CYLINDER+HEAD+COVER/parts....
by Volker_P
Wed Aug 24, 2016 12:28 am
Forum: General Discussion
Topic: Cylinder Head Temps
Replies: 8
Views: 2250

Re: Cylinder Head Temps

Stop and go in summer is the worst case for an airhead engine. You can kill every airhead that way (or even by infinite idle on the side stand). No real criterion for engine modifications. ... the bike started overheating to the point that it felt critical that I ride the breakdown lane to get some ...
by Volker_P
Tue Aug 23, 2016 3:31 am
Forum: Technical Discussion
Topic: Throttle butterflies dont retract?
Replies: 5
Views: 1532

Re: Throttle butterflies dont retract?

Throttle butterflies and choke butterflies are two different things. The throttle butterflies only exist for the CV carbs, the throttle for the piston carbs directly acts on the pistons. The choke is purely mechanical for both, the choke cam is two halves connected by a spring mechanism shown below ...
by Volker_P
Tue Aug 23, 2016 2:58 am
Forum: General Discussion
Topic: Cylinder Head Temps
Replies: 8
Views: 2250

Re: Cylinder Head Temps

Seems awfully hot but there's no real spec so who knows. I am not aware of overheating problems reported for the CB 650. If you just ride on the road this should be no issue. For a time I had a thermometer at my oil pump but it never exceeded 100°C. This is low compared e.g. to a Honda 650 RFVC sin...
by Volker_P
Thu Aug 18, 2016 4:52 am
Forum: Technical Discussion
Topic: Engine
Replies: 8
Views: 2288

Re: Engine

Well, in the manual linked below there are some drawings that provide some visual hint. So you roughly get to know where the longer bolts go in. E.g. page 10-0 is for the crankcase and there are other drawings like that, too. But if your really want to know and compare the correct millimeter lengths...
by Volker_P
Wed Aug 17, 2016 1:35 am
Forum: Technical Discussion
Topic: New to me cb650 custom 1980. Where to start
Replies: 1
Views: 936

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

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: The oil filter was installed incorrectly and it was one quarter low on oil.(fixed...

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