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SOHC.co.uk Forums => CB750 => Topic started by: adriangsmith on May 13, 2017, 03:32:19 PM

Title: CR carb issues CR750
Post by: adriangsmith on May 13, 2017, 03:32:19 PM

Hi All,
Just finished rebuilding the engine for a friends CR750.
All up together and would not start.
Traced to blocked jets in the carbs.
I removed all the jets and cleaned them out but now have petrol coming out from the overflow holes as marked in the picture below.
Floats valves still shut off manually so not sure if floats have perished or somehow the levels have changed.

So is there anyone who services these carbs in the UK?
Looking for a quick turnaround as he wants to take it to the classic TT in a couple of weeks.

Thanks All

Title: Re: CR carb issues CR750
Post by: philgresty on May 13, 2017, 04:49:06 PM

remove the floats and submerge them in water, if there is a crack in the float, it may be filling with petrol and sinking

Title: Re: CR carb issues CR750
Post by: royhall on May 13, 2017, 05:19:51 PM

The Classic TT is not until the end of August. Matt Harper at "Harpers ultrasonic" is a carb genius  http://www.harpers-ultrasonic.com/ (http://www.harpers-ultrasonic.com/) Ironically he builds the carbs for a number of the teams racing at the Classic TT.

Title: Re: CR carb issues CR750
Post by: westfieldandy on July 17, 2017, 03:03:30 PM

I use cr's on all the customer racers,

they are prone to flooding, usually just fine dust in fuel is enough,

always use a clear in line filter, do not rely on the gauze around fuel tap.  make sure float valves are good

make sure floats are good and set correctly,  my guess its just dirt, so many customers bring them to me swearing they've cleaned them out, and the tank, and there is still stuff getting through, the clear in line filter give a visual indication as to whats getting through.

andy
www.good-bits.co.uk