Stripping and rebuilding a standard Lambretta dell'orto carburettor is a fairly easy task, if you take your time, as the carburettor itself is fairly basic. Most of the items to worry about are housed in the lower float bowl section, these include, pilot jet, starter jet, main jet, etc. For those of you that have some technical knowledge, you may find the instructions too simple, but this guide is to assist those with no knowledge and so are basic!

I am going to presume that you can operate a screwdriver, if you can handle that you can strip and rebuild your carb!

These set of instructions apply to all series three carbs, the SH18, SH1/20 and SH2/22. Normally there will be an 8mm bolt to undo to release the carb from the manifold. Undo this, it is behind the carb itself. Next release the throttle cable nipple from the arm. Unscrew and take off the air hose. A 10mm spanner will be needed to undo the choke housing. Pull the choke assembly out in one go. The carb can now be tapped, and I mean tapped carefully, from the other side of the scooter so you're tapping at the back of the carb, with a block of wood or similar. Take care not to damaged the rear of the carb. You may need to increase your force to remove the carb, but be careful.

You should now have your carb in your hand ready for action!

There are two screws to undo that will release the top of the carb, when you have done this the cable holder adjuster block, along with the carb slide assembly will come out. Leave this assembly together, as we only need to clean this section, and you can get to all parts as is! Just inspect the slide to see if there is any damage.

Fuel banjo (where the fuel enters) is the next thing to take off, just unscrew it, and then remove carefully the small filter

The Float bowl screws are slightly lower than the two screws you just took out to remove the top. Undo these and the bowl will fall away. Note there will be petrol in here so be careful not to spill it over you dinner jacket (well I dress up to strip my scooter anyway!)

Undo the three brass jets you can now see with the carb turned upside down. Use the best fitting screw driver you have a yes brass is softer than your steel screwdrivers, so the jets will come off worse if you force them

there is a small pin that holds the actual float in position, a small pair of pliers should be enough to "wriggle gently" the pin out. The bowl will now be free, but note the float needle sits in there so do not loose it!

Unless I have forgotten any thing, the last part to dismantle is the air mixture screw on the side of the carb. It will be a screw with a spring on it. Just unscrew it! If you are unsure of any of the above, just look at the instructions below for re-fitting, and work backwards!!!

OK your stripped, I hope no one is watching!

Although the picture is not clear, this carb is now spotlessly clean, so should yours be!

Right clean everything in sight, and I mean clean and everything, some people can cause more problems, and make the carb dirtier than before they started. I start my rebuilds with clean hands, they stay this way right to the end!!!! Carburettor cleaner can be purchased in most motorist's shops, it is really good for shifting oily deposits that can build up as time goes by. Failing this a good soaking in neat petrol will be the next best thing.

We should presume that your carb is standard and that all jet sizes are correct to your machine. Next project is to upload all the corresponding sizes etc., for all machines, I shouldn't be to long with this so sit tight. There is no real set order for re-building the components, just as long as they all go together in the correct places. Do not over tighten any BRASS jets (yes they all are) you are fitting as they will damage first. They all just need to be "nipped up" with very little pressure, if you do go wild you will damage and or break them.

	Step 1 an empty shell is shown in the top picture, and on the bottom is shown where to fit your atomiser, in the centre hole. This just needs to be nipped up, not over tightened! New atomisers are rarely needed as the do not tend to wear, you just need to check you have the correct size, stamped on the top side edge, there are four sizes, 5889-1, 5889-2, 5889-3 and 5889-4.
Step 2 Now working from the top picture, fit a new main jet into the atomiser (fig 1) that you have just fitted, again check you have the correct size for your model, they range from around 70 something up to 117 in standard format, but you can get higher if you have a tuned scoot. The choke or starter jet which is the longest one (fig2), can also be fitted again your old one when cleaned up will be fine, unless you can see visible damage. The bottom picture shows the small pilot jet, new should always be used and it fits in where (fig 3) is shown on the top picture.
	Step 3 Yes we cheated in step two's photos, but we can fit the float, needle and pin now! In the top picture the float needle is tilted into the slot on the float. Notice the black tip that the line is pointing to. This will almost certainly have a ring around it where the needle has been sitting in the housing, new ones are totally smooth in their taper so fit a new one. This is what controls the flow of fuel into the carb, so if you have a ring it may not seat properly and fuel will continue to be allowed in, this causes flooding. Fit the needle into the float, turn it upside down, and lower the needle into the hole. The last picture at the bottom, shows the pin being fitted, just tap this gently home with a handle of a screwdriver. The pin does not disappear into the housing it does sit out proud. this allows you take it out next time!
Step 4 Now its time to take care of where the fuel enters the carb and goes into your float chamber section you have just built. First push the filter into the carb body as shown in the top picture. Two new gaskets are shown in the second picture, a larger one that fits inside the banjo, and a smaller one fits on the screw, rather like a washer. These two gaskets again should really be renewed, although I have used the old ones many times with success! Fit the banjo, some have a peg and hole part to line them up, others do not. For the carbs that do not, make sure your inlet pipe is positioned at the angle shown on the photo, this will stop the lug from catching on the engine mount!
	Step 5 Just before you fit the float bowl, you can now blow through the banjo you have fitted (where the fuel enters the carb) and push the float open and shut to make sure the needle is working correctly, i.e. when the float is hanging down you can blow, and when you push the float up, you now cannot! The top picture shows the float bowl fixing screws. The next picture shows the air mixture screw, and circled is where it fits. When fitting this you should turn the screw with your hand all the way home, then you turn it backwards to set it. Although there are specific amounts of turns to each individual carb/machine a general rule of thumb is turn it back out one and a half turns.
Step 6 If you did need to change your slide can see quickly how it goes back together in the following pictures. slide the slide onto the slide arm and then fit the spring on the round housing at the top and into the round housing in the carb top. Once you have this in the correct position, the whole assembly can go back into the body of the carb, and be screwed down.
	Those of you who have been taking notice will see from the picture that my fingers are still clean, and we ever so nearly have a completed carburettor. All we have to do now is put the carb back onto the scooter. Tap the carb back onto the manifold, if you do not have a rubber hammer, gently use the handle end of a screwdriver, tap until the carb will go back nor more! Fit the throttle cable back on, then with taking notice how the carb is standing perfectly upright, tighten the 8mm securing bolt at the back. The next two photo's shows how to re-fit the choke valve if you took it off. Slide all components together, elbow, adjuster, block, and then the spring, force the spring to compress with your finger nails, and slide the choke valve into position. The assembly will then hold itself together while you re-fit I into the carb body.
The Final set up! The throttle cable should have no play in it, that is as soon as you turn the throttle grip the slide should be going upwards also. The other side is that the slide should be able to sit fully down, without the throttle keeping it up! Where the outer cable stops, is an adjuster, screw this inwards or out wards to gain the correct adjustment. If you notice in the picture there are two small holes either side of the air inlet large hole, the one on the left, is where the choke valve sits. Look through this hole and make sure that when you turn the choke on, the valve does lift up, adjustment is by the screw at the top of the housing where the cable goes in. Final things is to get the scooter warmed up by riding around the block a few times, and adjust the tick over. This is done by turning the screw where the inner cable sits at the back of the carb near the fuel tap. Adjust it to your desired position, rev the scoot a little and see if all is well. The perfect idle speed will be where the scooter is just about running but does not stall.
Well I hope this has all helped, many of the superdealers listed, will be able to offer you advice and spares for your carb, If this article has not helped, you can send me your carb to be re-built along with large amounts of cash oh all right then just ask me and I'll try and help
Typical problems and cures Engine cuts out Main jet blocked, Tap or tap filter blocked, Carb filter blocked, Air inlet in tank filter cap blocked, Water in fuel, Float chamber filled with two stroke oil (caused by not turning fuel tap off). Possible ignition fault also Engine will not tick over unless choke is on Pilot jet or pilot feed passage is blocked, Pilot air screw not adjusted correctly, Worn throttle slide, Carb top loose Engine ticks over but will not rev Throttle cable broken, Throttle slide detached, Silencer blocked, Ignition fault Engine "4 Strokes" choke on or stuck on, Choke cable to tight, Air scoop under seat blocked, Air filter needs replacing Engine misses or backfires Dirty or faulty spark plug, Air hose detached or split, Air filter missing. See also faults for engine cuts out. Engine will only run with choke on Crank case oil seals blown, Main jet blocked, Air filter missing, Hose split or missing Engine will not start when hot, Float needle needs replacing, Throttle slide worn, See also faults for 4 stroking Engine smokes Too much oil in your petrol, Drive side oil seal blown allowing oil to leak into crankcase, Choke stuck on Engine will not switch off when hot Overheating (need decoke), Wrong grade of spark plug, Engine running weak - air filter missing other air leak at manifold or carb top, Exhaust pipe loose Throttle does not open fully Incorrect fitment of slide spring, fuel tap interfering with carb tie rod ass, Throttle cable detached at handlebar end. Take me to the top of the page!!!