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Author Topic: Help trouble shooting  (Read 238 times)

Offline DanielK

  • Posts: 57
Help trouble shooting
« on: Sep 17, 2018, 14:26:07 »
I've gotten some problems with my cb650.
Specs are:
Dyna S ignition
OEM coils with extra resistor
Pod filters
120 main jet
42 pilot jet
Mixture screw 1.75 turns out

My problem started with a clogged fuel filter. Changed to a new one. Then I drove the bike about one tank of fuel. Then i leaned out after some riding and died. Change fuel filter again and it ran for less than one tank of fuel. After this i cleaned the carbs with brake cleaner and compressed air.

After this the bike ran fine for 100 miles. Maby with some rpm overshoot when changing gear when warm. After this it missfired and ran on 2-3 cylinders. Managed to get to a gas station and it cut out at the pump. Filled up and it started and i drove the last mile to work.

After this it started to just run for 10 minutes and then I hade to let it rest for a few minutes before I could drive for a few minutes. I think it runs lean before it dies and after restart. When i release the throttle and pull the clutch it revs up and then idles.
Today I could only ride for 5 minutes before it missfired and cut out 1 or 2 cylinders. Let it rest for a good 5 minutes but could not get it to run good. Drove the last 1/2 mile home sounding like crap.. not the 4 cylinder sound.

Any ideas? Float hight? Bad coil?
--Daniel
CB650 -80

Offline DanielK

  • Posts: 57
Re: Help trouble shooting
« Reply #1 on: Sep 17, 2018, 14:47:27 »
Forgot one thing. It does not help to twist to full throttle when it starts to run crappy.
--Daniel
CB650 -80

Offline jpmobius

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Re: Help trouble shooting
« Reply #2 on: Sep 17, 2018, 15:27:04 »
Make sure your gas cap is venting.  If this is the problem, it likely will be much more pronounced on a full tank than on a mostly empty tank. 
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline DanielK

  • Posts: 57
Re: Help trouble shooting
« Reply #3 on: Sep 18, 2018, 15:56:43 »
Will check tank vents, but I think I have another odd thing. When I start it cold at full choke it has very low revs. If I push the choke in a bit it revs up alot. Push it in some more and I get more of an idle.

This weekend I'll measure float level and check float level with the clear tube method.
--Daniel
CB650 -80

Offline advCo

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Re: Help trouble shooting
« Reply #4 on: Sep 18, 2018, 15:57:57 »
Sounds like a potential vacuum leak.
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline DanielK

  • Posts: 57
Re: Help trouble shooting
« Reply #5 on: Sep 22, 2018, 03:37:23 »
My major problem is solved! It was a bad coil.

Still have som issues. I think it runs a bit lean. When I pull the clutch for a gear shift with a hot engine the rpm increase and then comes down.


Sent from my iPhone with Tapatalk
--Daniel
CB650 -80