Cylinder #1 is not firing

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

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Corvus
Posts: 21
Joined: Tue Jun 19, 2012 9:58 pm
Location: Ashland, OR

Cylinder #1 is not firing

Postby Corvus » Fri Sep 28, 2012 12:53 am

Hello again, My '81 cb650c is having troubles again, the worst of which is me. Yes, the same me that decided the oil leaks were just too bad and the gaskets all needed to be replaced. Everything is back together and happy except Cylinder #1 isn't firing.


I am compression testing it in the morning.

here is the summary so far:
Carb float/jet/etc are fine
Spark plug is fine
Crank to Cam timing is manual and theory correct
Ignition timing and static timing are perfect
Rocket valve clearances got tuned to manual specs
Airfilter is dirty, but fine for the moment
I've tested the (the word fails me, thing that sends power to the spark plugs) and it is not the issue.

so, it has gas, spark, and air, but no combustion? If tomorrow I check the compression and it says it is correct, what should I do?

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bolo79
Posts: 65
Joined: Sun Aug 15, 2010 9:51 pm

Re: Cylinder #1 is not firing

Postby bolo79 » Fri Sep 28, 2012 9:42 pm

Hi.81 These pressed into slow jets. :x If a compression test will be acceptable,you have a spark and the fuel in the float bowl,then it's time for honest question.How clean are yours slow jets? :lol: I hope this is jet or something else not a gasket.Good luck tomorrow.

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Corvus
Posts: 21
Joined: Tue Jun 19, 2012 9:58 pm
Location: Ashland, OR

Re: Cylinder #1 is not firing

Postby Corvus » Fri Sep 28, 2012 10:36 pm

I had time today so I took it apart. Compression was the issue. I have a bent intake valve. Any idea where to get one?

It gets better though. It looks like the cylinder has never fired since I bought the bike. This is the largest bike I've had so I didn't notice the severe lack of power. We looked at the exhaust and there was no soot of any sort in the pipe on cylinder one versus enough to dirty a finger in all of the others.

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

Re: Cylinder #1 is not firing

Postby Volker_P » Thu Oct 04, 2012 1:48 am

Check out the other valves, too!
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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Corvus
Posts: 21
Joined: Tue Jun 19, 2012 9:58 pm
Location: Ashland, OR

Re: Cylinder #1 is not firing

Postby Corvus » Thu Oct 04, 2012 3:25 am

Volker_P wrote:Check out the other valves, too!

I checked them with a feeler gauge and them all seemed to seal except cylinder 1's intake. After getting a new valve in I'll try a liquid test.


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