Fuel pump


What is the Malossi piece needed to mount a Dell’Orto fuel pump, I receive a little piece with the pump but I don’t know if it’s the good one, see picture joined.

It seems that the art. number is 4043 on SIP.

This is what’s written :„Connecting piece SIP for
MALOSSI reed-valve manifold,
75x42x41cm, attention: additional connecting piece necessary“

tanks beerece to put it in same good english and well organized answer.

Hello It’s just a try!

No I didn’t fit it yet, I am searching over the shops here for the cold welding before making the hole.

Somebody told me before that the boost bootle was just for visual effect and was not really effective! What do you think all of this?


Hi Mikkke, his name is Dave Hampson and his email is:

[email protected]


hello mikkke,

no it is not fuel starvation if goes well in the shorter gear.
The higher rpm you get the easier is to experience a fuel starvation which effects are really evident. It is not that your engine can’t climb in the higher rpm but it cuts, you have a hole like when you cut the engine with the key.

Mikkke, I am a lazy b… in this moment.
I found the little thing but taking a picture and posting, maybe in the week- end , but you could use the plug nipple as beerace suggested you or I think could do it even the… you know the thing under the engine where you pass the clutch cable? You coud cut the long and smaller part that screw in the crancases and you end up with a reductor… just check it if the outside is more or less 8mm so could fit nicely inside the fuel hose…

I went back from my ride, I tried with a 130 mainjet but no fourth gear, it run faster in third than in fourth I try with the mixture screw at 1 1/4 and at 1 1/2, it’s the same nothing better or not.

Than I tried to put a 125 mainjet it’s better but the same thing in fourth but this time I can ride in fourth but no more speed and power than in third, I only reach +/-115km/h not many compared to before all those mod, any idea???


No, I don’t fit it, I don’t even think I could put it with the manifold I have to check but I don’t think.

Is it a black rectangle part?

So you got it now!!

Good job friends, working together gonna make us go longer and longer…

Hello Captain Scooter!! (Cool forum)

Can you tell me more about the reduction in the circuit, I don’t understand what you mean!

Here in Belgium it’s getting a little more hot without ice and rain, hope I’l ride a little to test this we!!!


ok thanks , good night, see ya tomorrow

hello Mikkke,

yes the position is where you indicated in the picture.
I am happy it is of the right size. You know I have just tought before suggesting you but never tried. (was the piece for the clutch I think?)

Let’s go first on the carb set up before other thing.
When you do the plug chop with 125 youi have a good colour?

Then when you talk about the 4th gear you feel it that the engine can’t get in the range where it starts to push or something else?

And remember me you gear ratio. I remember was of highsh type.
And if you have an espansion exhaust as I think you have (if I remember you have a SIP) it is normal.

For me, I think I have already told you, you should go to 21/65 or even 21/68.

But tell me again please your gear ratio.

hello Mikkke,

yes the visual effect is for sure, the effect on the engine is in the most evident case fairly small and restricted in a particular rpm range, in other case inexistent. This is my experience…

Ade,I don’t know if it’s the same but you can find it here I think.

Hi Mikkke and Curare, I will try a different way of explaining. Effectively you have: a pipe from fuel tank to the fuel pump, a pipe from fuel pump to carb. On both of these pipes there should be a T piece linking to each other (This linking pipe allows pressurised fuel to the carb to recirculate back to the feed pipe when the float bowl in the carb is full as the pressure is enough to force the float needle open and either flood the engine or out the overflows) The restriction has to go in the linking pipe to encourage the fuel to go to carb rather than just recirculate. The easiest way to acheive the restriction is to put the little piece af aluminium / top of a spark plug inside the linking tube (Just slide it inside and forget about it)(I mean the little „tit“ you take off when using a ngk cap!). I recommend blanking off the breather pipe insipe the tank (Brass tube sticking up) either crimp tight or solder with ELECTRIC NOT GAS soldering iron

Hello Mikkke, the small piece that fits into the Malossi reed block is called a stuffer. Did you fit it yet?


Curare, I know how to fit the pump, but my question now is; my manifold is adapted with a fitting for a boost bottle, the same as for a fuel pump, can I fit a boost bottle as well as the pump? or would the boost bottle affect the working of the pump? should I fit another take-off vent higher up the manifold for the boost bottle? my idea is that the boost bottle will affect the vacuum pulses necessary for working the fuel pump, but if I can fit both I will try it.

ok guys, Curare, never mind for the 65, I will change my ratio as soon as the money let me do it!!

I will try to fix the idle screw this evening like you say to have a good response from idle.

I think that my engine respond well in neutral, my manifold seems to be flat, but I am not very sure, my crankshaft is standart but I have to change it too, you remember?

I will try to let you hear my engine.
As the engine respond well in 1,2 & 3, is it possible to have a fuel starvation as the fuel pump is not mounted yet?

Thanks all for your perfect and more than useful help!


Hi Sliphorn,

Can you give me the adress for the jumbo tank of 11.5l, there were some on Stoffi’s or Worb5 web but I can’t find them anymore, it should be useful.

I miss to join the picture!!