40mm Dellorto Float height

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customhead
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40mm Dellorto Float height

Post by customhead » Sun Mar 24, 2019 3:51 am

I have overhauled the carby from a Gilera 500 and found the float had let a lot of fuel thru overflow and into the cylinder.
luckily i could hear it and removed sparkplug for safety.

BUT! The Gilera Saturno manual says the float height should be 24+/-2mm
My Dellorto manual says PHM carbys are to be set at 18.5 - 17.5

it would seem dellorto is incorrect seeing as I have overflow.

Anyone have experience with this problem?


Sean

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Joachim
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Re: 40mm Dellorto Float height

Post by Joachim » Sun Mar 24, 2019 9:04 am

if i remeber right i have always used the value from the Gilera manual.
So maybe you should give that one a chance ;)
On the other hand, the fuel valve is ok? Not leaking? New?

ciao Joachim
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lambs
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Re: 40mm Dellorto Float height

Post by lambs » Sun Mar 24, 2019 11:33 am

customhead wrote: Sun Mar 24, 2019 3:51 am I have overhauled the carby from a Gilera 500 and found the float had let a lot of fuel thru overflow and into the cylinder.
luckily i could hear it and removed sparkplug for safety.
If you haven't already, suggest changing the float needle (+ seat, if its of the replaceable type). The new type float needles use a viton rubber tip, which is better for modern fuels.
customhead wrote: Sun Mar 24, 2019 3:51 amBUT! The Gilera Saturno manual says the float height should be 24+/-2mm
My Dellorto manual says PHM carbys are to be set at 18.5 - 17.5

it would seem dellorto is incorrect seeing as I have overflow.
I'd tend to stick to the Gilera manual spec but, yes, the dellorto manual float height spec would lead to a higher fuel level in the float bowl and consequent richer mixture. However, overflow shouldn't occur if the needle and seat are in good condition.

customhead
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Re: 40mm Dellorto Float height

Post by customhead » Sun Mar 24, 2019 11:40 pm

the tip is viton and whilst changing things is always better, the condition looks good.

I will stick to the Gilera manual although "Turn over the carburettor and let float rest on the needle's damper"
annoys me as there is more than one way to turn a carburettor :)

lambs
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Re: 40mm Dellorto Float height

Post by lambs » Mon Mar 25, 2019 3:01 am

customhead wrote: Sun Mar 24, 2019 11:40 pm the tip is viton and whilst changing things is always better, the condition looks good.
Looks like the seat is also replaceable on the PHM, so something to consider if problems persist.
customhead wrote: Sun Mar 24, 2019 11:40 pmI will stick to the Gilera manual although "Turn over the carburettor and let float rest on the needle's damper"
annoys me as there is more than one way to turn a carburettor :)
This might help:

http://www.thisoldtractor.com/dellorto_ ... etors.html

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