SOHC.co.uk Forums > CB350/400
cheap ultrasonic cleaner
Bryanj:
You really need to instruct the owners that dishwashers ain't toilets!!!
mike the bike:
Already done
paulbaker1954:
Just to add my 3 cents. It is important to make sure thatt he internal passages are clear ESPECIALLY the idle circuit. Below is a description I posted a while ago of how I checked these were clear.
The idle circuit consists of 3 holes and the pilot jet.
hole 1 can be seen on the carb wall on the inlet side throat at 90 degrees from the top before the throttle slide, this actually joins in to the hole from the air screw by the way.
Hole 2 is a VERY small one at the base of the throat on the exhaust side at 180 degrees from the top just in front of the throttle slide. This is where the idle mixture is fed in to the cylinder.
Hole 3 is where the air bleed screw goes in.
At idle air is drawn from hole one and the air screw then adjusts the amount of incoming air, this is then mixed with fuel from the pilot jet To provide the idle mixture.
The resulting mixture then squirts out of the very small hole (hole 2) at the front of the throat in to the cylinder.
I found the best way to check for blockage in the whole pilot circuit is to remove the pilot jet and air screw and blow down the air screw hole and at the same time cover the pilot jet hole and the other 2 holes with some combination of fingers and thumbs. You can then lift a finger or thumb from each hole in turn and hear if you get air blowing through.
It's a bit like mastering playing the bagpipes but an effective way to check the circuit for blockage.
This may sound complicated but if you find the holes and study the plenum chamber in the base of the carb it's pretty obvious how it works.
Hope this helps fellow owners with idle/suspected blocked carb issues.
I must apologise for my lack of foresight in that I should have taken some pics whilst the carbs were off. If I take them off again in the near future I will post pics to show where the relevant holes are.
Pops400:
--- Quote from: paulbaker1954 on October 31, 2016, 10:21:19 AM ---
I found the best way to check for blockage in the whole pilot circuit is to remove the pilot jet and air screw and blow down the air screw hole and at the same time cover the pilot jet hole and the other 2 holes with some combination of fingers and thumbs. You can then lift a finger or thumb from each hole in turn and hear if you get air blowing through.
It's a bit like mastering playing the bagpipes but an effective way to check the circuit for blockage.
--- End quote ---
The mental image this has conjoured up has still got me chuckling... ;D
mike the bike:
As I was reading it, my brain was already thinking of bagpipes before you mentioned it. Uncanny, or was it the haggis I had for breakfast?
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