Carburettor problems

[redroadster]

Hi,
I bought this vtr knowing that it need looking at. Today I have had a good look, got it started but it is only running on 1 cylinder. Stripped the top down, checked the plugs and spark ok. Started up again and tried feeding fuel into the carb air intake, when done on the front cylinder she ran on 2 cylinders. I removed the carbs, removed the float bowls, all looked reasonably clean, removed the jets, clean in ultrasonic bath, blew out and reassembled everything. Checked the diaphrams, refitted to bike but the same fault occurred. The bike has been stood for a couple of years, the inlet rubbers etc all look ok. Has anyone any suggestions what else to look at?

Cheers Mike

[jchesshyre]

Check that the blanking screw in the port for fitting a vacuum take-off in the front inlet isn't missing, or if it's been replaced with a stub and hose, that the hose is capped with something.

Location is on page 3-12 of the Honda workshop manual.

[redroadster]

Only have the Haynes, is this on the carb or on the cylinder head? The reason I ask is there is a discoloured tube coming from a the cyl head with a bolt screwed in the end, it does not look like a factory fit. The vacuum tube coming from the same point on the rear cylinder goes to the fuel tap

[tony.mon]

That's a good thing re the tube, it's been fitted with vacuum take off point for carb balancing.
Is there a spark on the missing cylinder?

[alanfjones1411]

Only have the Haynes, is this on the carb or on the cylinder head? The reason I ask is there is a discoloured tube coming from a the cyl head with a bolt screwed in the end, it does not look like a factory fit. The vacuum tube coming from the same point on the rear cylinder goes to the fuel tap

If the bolt screwed into the discoloured tube is threaded all the way to the bolt head could be taking in air along the thread.I have a golf tee in mine.

[tony.mon]

Only have the Haynes, is this on the carb or on the cylinder head? The reason I ask is there is a discoloured tube coming from a the cyl head with a bolt screwed in the end, it does not look like a factory fit. The vacuum tube coming from the same point on the rear cylinder goes to the fuel tap

If the bolt screwed into the discoloured tube is threaded all the way to the bolt head could be taking in air along the thread.I have a golf tee in mine.

A smear of grease or silicon sealer ensures an airtight fit.