changing the gas valve in a carb

[steven_191]

i have a dellorto PHBH 28 RD with a 40 gas valve that has some wear and tear marks on it. i also have a 45, 60, 70 and maybe some more than are in almost perfect condition.

i dont know anything about the gas valve and what the difference between them is. could anyone enlighten me and tell me if anything would be wrong if i put the 45 in place of the 40?

[temeluchus]

gas valve?

this the one in the bottom, controlled by the needle and float?
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Some shite cruiser. Now with guns and FREEDOM!

[steven_191]

gas valve, or slide. first on the left in this picture. its what the throttle cable locks into and the needle is fitted to

[temeluchus]

ah right. the choke.

Um..... may or may not be the same, not too clued up on dellortos.
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Some shite cruiser. Now with guns and FREEDOM!

[baldy]

That is the slide, not the choke.

I can't see it making a massive difference as long as they are the same and actually fit in. Does it look the same?

What is wrong with the old one? does it get stuck or rattle around?

I have seen some pretty worn out slides before which caused no problems at all.

I would just give it a go. It can easily be changed back.
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One day i will rule the world, just not today.

[temeluchus]

[steven_191]

its not the choke


yeah the old one fits ok but the other one is in better condition. i was just wondering whats the difference. there must be a difference otherwise why would they have the difference numbers stamped on them.

the WSM says that it need either a 40 or 60 but have different setups on the same carb and same engine??

[temeluchus]

terminology aside, the shape of the bottom may be different among other things. The shape of the bottom of the slide can affect part throttle pickup.

Have you fitted the slide? does it fit?
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Some shite cruiser. Now with guns and FREEDOM!

[steven_191]

yeah fits and slide fine. im going to get a picture of the others as well today, they all look the same. this is why i wondered what the difference actually was

[steven_191]

i have found that the difference is the height of the cut away from the back of the slide. the larger the number the more the cut away. so i assume that would mean more air flowing through the carb.

ill upload a picture later, the difference between the 40 and 45 is hardly noticeable but between them and the 70 you can easily tell.

would the 70 make the carb more or less responsive?

[steven_191]

heres the pic. from left to right, 40, 45, 45, 70. you can see the difference in the bottom edge

[Odie]

was it running ok with the old one?
if it was put the thing back!
also concerning the cut away on the front of your slides, it is nothing to do with letting more air in as you carb venturi is pre set (dia of the inlet from air box to carb)
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[steven_191]

ive not had it running yet. the one that was in there just had a lot of marks on it. what difference does it make then?

[temeluchus]