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CB750 Barn find project - First Timer
sye:
Could be vacuum in the tank caused by a blocked breather. Take the fuel cap off when it conks out and if air rushes in it could be the culprit.
Underdog1:
--- Quote from: Rob62 on August 25, 2018, 04:14:21 PM ---Conking out after 15 mins then not starting till cooled down sounds like an electrical component failing at higher temperature... coil maybe. Or it could be fuel starvation but unlikely....
--- End quote ---
Could be the condensers, they are the original ones.
Didn’t have any tools with me to check the spark, was thinking at the time it would be ideal to have a spare spark plug in my pocket as I could do it with no tools
Underdog1:
--- Quote from: sye on August 25, 2018, 04:38:58 PM ---Could be vacuum in the tank caused by a blocked breather. Take the fuel cap off when it conks out and if air rushes in it could be the culprit.
--- End quote ---
Tried this at the time, didn’t make a difference
K2-K6:
Not too rich is it? Just chokes it when warm possibly.
What colour are the plugs? Do they indicate rich setting or the opposite?
If rich, crank it with throttle wide open to get more air in and it may go.
There are breathers into the float chambers of each carb that allow the fuel level to stabilise, you can run into problems with filling if these are not all clear.
As a means of diagnosis, when it stops you can open the throttle and spray some easy start into the carbs via the filters to see if it'll fire again straight away.
Underdog1:
--- Quote from: K2-K6 on August 25, 2018, 07:25:43 PM ---Not too rich is it? Just chokes it when warm possibly.
What colour are the plugs? Do they indicate rich setting or the opposite?
If rich, crank it with throttle wide open to get more air in and it may go.
There are breathers into the float chambers of each carb that allow the fuel level to stabilise, you can run into problems with filling if these are not all clear.
As a means of diagnosis, when it stops you can open the throttle and spray some easy start into the carbs via the filters to see if it'll fire again straight away.
--- End quote ---
Just popped back out to ensure the battery was charging properly and it roared to life on the button no problems.
I did try cranking it with open throttle when I was stranded earlier and anything it seemed even more reluctant to start some how. By breathers into each float chamber do you mean the little tubes that join each carb bowl pair together (connected by a rubber tube)? I was meticulous in cleaning the carbs - soaked in carb cleaner, scrubbed, wire pushed through holes, multiple passes fully stripped down in a US cleaner, blew through with compressed air rebuilt with all new bits etc..
I’ll check the plugs out tomorrow, jetting is probably out and they haven’t been synced yet.
What’s a symptom of a dodgy condenser?
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