Author Topic: cb250rs carb question  (Read 92 times)

spooky

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cb250rs carb question
« on: January 02, 2022, 11:01:14 AM »
On the bottom near side of the carb float bowl there is a drain screw, if this is removed should petrol run out with tap on or even with tap off ? I am wondering if there is something in float bowl that is occasionally blocking it , I don`t want to take float bowl or carb off until I know, 
Classic efi squadron blue, Conda 250, Terrot 125, Negrini 50,

themoudie

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Re: cb250rs carb question
« Reply #1 on: January 02, 2022, 04:54:12 PM »
Aye Rufus,

Back in from a canter on the Ducati, a wee bit blowy and rain coming in fast from the west, but not a bad run.

Now for your carbie query! Although I have never had to deal with one these beasties, I suspect that they are not disimilar to other Honda carbs. If the fuel tap from the tank is turned 'OFF', you should be able to drain the carb bowl by slackening the drain screw. N.B. these have a taper and a rubber 'O' ring seal to keep them fuel tight!

So, yes, you will have an initial fuel flow, with the fuel tank tap 'ON' or 'OFF'. But, in the 'OFF' position, the fuel flow should only be the contents of the fuel line and carburettor float bowl.

Spare parts prices on the CMSNL site aren't cheap, but then what "Classic" Jap parts are these days ?!  :(  A complete carb is £405 and a rebuild gasket kit is £28-74 inc 20%VAT, but no P&P.

I thought AMAL parts were expensive, but not compared with these. However, these were a better carb and have a diaphragm pump in them.  :-\

A good exploded diagram for the carb is available on the CMSNL website and this can be enlarged in a separate tab.

Here is the link: Honda-CB250RS-1980-a-England_model_carb

Here is the separate link to the exploded parts diag: Honda-CB250RS-1980-a-England-carb_exploded_diagram

Fowlers, Dave Silver, WeeMoto for parts.

Good health, Bill

spooky

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Re: cb250rs carb question
« Reply #2 on: January 02, 2022, 06:06:11 PM »
Thanks Bill, interesting, when i take drain screw out nothing flows, with tap on or off  ?, if I pull the fuel pipe off the carb petrol runs well from tank,  something stuck somewhere ?
Classic efi squadron blue, Conda 250, Terrot 125, Negrini 50,

themoudie

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Re: cb250rs carb question
« Reply #3 on: January 02, 2022, 11:41:21 PM »
Aye Rufus, sounds like sludge etc in the float bowl. Be warned that float needle is no cheap!

However, with a wee clean and rebuild you might find those missing Freiberger or Haflinger horses. Or should that be a Noma uma?  ;)

Good health, Bill