Installing A 25mm DellOrto PHBL Carburetor

[90GTVert]

Installing A 25mm DellOrto Carb, Polini Intake, And Malossi Reeds

Here's the size difference between the 25mm PHBL Dellorto and the 19mm Arreche that I was using. It's easy to see why sticking with a smaller carburetor (when your setup allows it) makes life easier.


Here's the Polini intake and the stock intake. The Polini is longer to provide extra clearance for larger carbs.


Outlets of both intakes. I had ported the stock intake.


Malossi reed block vs reed block from Autotech355. There isn't much difference in the size of their openings, but the Malossi is a better quality product. Both have larger openings than the stock reed block (which I was too lazy to dig out for pics).






I removed the plug from the bowl of the Dellorto so I would know what main jet I'm starting with. It's a 102. The Dellorto is setup different than the Arreche. With the Arreche carburetor you pull the plug to gain access to the main jet. With the Dellorto the main jet is actually in the plug. I like both, but the Dellorto looks like it will be a bit easier.


The Dellorto comes with this style of cable adapter.


I ordered a few different adapters along with my carburetor. They don;t cost much and are nice to have in case you need them.


My stock cable isn't going to work with the Dellorto for 2 reasons. It needs a threaded cable adapter, and it doesn't have enough pull to open the carburetor all the way. If you notice discrepancies in photos and descriptions it is because I originally installed the carb with the stock cable and a different adapter. After having tuning issues I realised it just wouldn't work that way.


I had to switch to an aftermarket throttle assembly and cable to make the carburetor work properly.


Here's the carb hooked up to everything and with the unused intake ports plugged.


You can see that there is very little clearnace between the carb and frame now. From what I understand, smaller frame scooters may not fit a carb this size at all without relocating it. I've only got about 1.75" of clearance to fit an air filter.


The big K&N isn't going to make it in there.


I'll need to get a shorter filter or possibly one with a bend that has a 39mm opening.

I took my carb apart to get some info before I ordered anything. If anyone ends up with a 25mm DellOrto PHBL carburetor this info may be of some use. You'd still be better of to verify what you have though.

Specifications (as recieved) :

Main Jet : 102
Pilot Jet : 70
Starter Jet : 60
Atomizer : AQ266
Throttle Valve : 40
Jet Needle : D22
Jet Needle Clip Position : 2nd From Top



HERE is a great site for DellOrto info.