hi, Driving me mad is a dellorto phbh26 it s over flowing.

adjusted float height. its had a new float valve. turn it upside down blow down the fuel intake and its sealed,

put the bowl back on and it leaks fuel again.

scorpa easy 1996 250 rotax

any ideas?? rij

Have you seen this? ApexMotorsports It's a Montesa parts list but the page linked to is for the PHBH carb. May enable you make sure that everything is as it should be. Float height on these is usually 18.5mm. Have you got the overflow pipe on the right outlet? Are the floats free to move when you put the bowl back on? Impossible to see I guess but is there anything that could be stopping them moving?

Hi

Have you checked the floats are not punctured.

I had a float fill with fuel which caused a similar problem.

Hi Again

Also check that the floats are correctly orientated.

Flat to bottom of float bowl.

A good check is to give the carb a gentle shake after reassemby and hear the floats move.

Hi,

floats are ok not punctured, can't really tell if there moving when its all together but all seams free when the float bowl is off.

the diagram look the same all present and correct!

rij

Also check your needle valve is seating properly.

Try with the float bowl off fuel is stopped by slight pressure up wards ie needle is doing its job. Float height measurement upside down of course.

Ok can hear floats moving.

Carb assembled turned upside down blow down the fuel intake and it shuts off still.

floats are floating. turn correct way up and it leaks!! just taken apart completely no dirt everything blows through clean??

SOUNDS LIKE THE TWO FLOATS ARE INSTALLED UPSIDE DOWN AND SMALL TANGS ARE NOT PUSHING UP AGAINST FUEL VALVE ARM WHEN FILLING WITH FUEL AND OVERFLOWS BECAUSE IT WONT SHUT FUEL OFF AT WHAT SHOULD BE CORRECT LEVEL

Hi

the floats cant be upside down, it does not fit and would have to be forced to close it.

anybody got a cheap mikuni of a beta or tk off a tyz yamaha???

rij

I can confirm that the floats can be fitted the wrong way!

Ok can hear floats moving.

Carb assembled turned upside down blow down the fuel intake and it shuts off still.

floats are floating. turn correct way up and it leaks!! just taken apart completely no dirt everything blows through clean??

So you have tried it on the bike with the float bowl off?

yeah, float bowl off gently push float tabs up and it tuns off.

I've tried floats the other way but it would have to be forced on and that would keep the float valve shut tight.

i have got the floats i with the pin at the bottom. rij

yeah, float bowl off gently push float tabs up and it tuns off.

I've tried floats the other way but it would have to be forced on and that would keep the float valve shut tight.

i have got the floats i with the pin at the bottom. rij

Right so it is established to be working fine.turn upside down and check 18.5 and its done if it floods then something is happening when the bowl is on. brass thingy ok >?

yeah all look straight and original,

ive showed this to a couple of guys i work with, who are motorcycle mechanics and its got them baffled as well!!

i feel like grinding into a thousand pieces!!!

rij