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Carby

Posted: Sat Sep 17, 2016 4:29 pm
by whitehillbilly
Hi,
Just wondering if the two yellow tubes from the carby should actually be one piece and have snapped into to separate ones.
I have some new green chainsaw fuel pipe to replace it with.

Thanks.

Whitehillbilly

Re: Carby

Posted: Sat Sep 17, 2016 4:54 pm
by Gomey
That looks correct. There are vents.

Re: Carby

Posted: Sat Sep 17, 2016 6:08 pm
by Rod
As Mark states, they are vents and on most carbs they are separate and are angled downwards, however, I have a Fantic 300 in a very original unmolested condition with the Dellorto PHBH 26 BS and it's vent elbows are angled upwards and are linked together by the tube, the owners manual also shows a pic showing them angled upwards and linked. It runs nicely, so I've left it as is. The alloy elbows are only a press fit and can easily be removed or rotated. Also note that this particular carb, PHBH xx BS, doesn't have an air screw as such, it's actually a fuel screw, same function in essence but on a fuel screw in = lean and with an air screw in = rich.
I can't remember which model Dellorto's were which, but if you have an adjustment screw located closest to the motor then it's a fuel screw, if it's closest to the air filter then it's an air screw. Clear as mud really :? Hope this helps somehow.

PS: Just looked at your pics again, your Dellorto runs an 'air screw' unlike mine which has a fuel screw. Don't know whether this has any bearing on the type of vent tube setup (linked or open)?

Re: Carby

Posted: Sat Sep 17, 2016 6:37 pm
by whitehillbilly
Thanks for the replies.
interesting about the position of the adjusting screw.

whitehillbillies

Re: Carby

Posted: Sun Sep 18, 2016 3:53 am
by don.howison
Those ports are vents and must be open to atmosphere. As stated it was common practice of some Euro bikes to link them together with one tube but what they did was knick the side out of the tube around mid point to open it to atmosphere. If you don't have these ports open the carby will not function correctly.
Good luck. Cheers Don