I had a lot of trouble initially with the Dell'Orto MA16b on my bike. You can obtain some new parts through Dell'Orto here in the UK - even for older carbs! New bodies are harder to come by, especially since these were common on classic scooters of the period so you're competing for old carbs with the scooter crowd as well.
I've gathered a fair bit of info on the MA16b (if that's what you have) and you're welcome to it. One other thing to check for is that the float weight is correct. Should be 6.5 grammes. A second-hand carb I came by had a 7.5 gram float in it! Needle should be a D8.
If none of this helps you should consider the possibility that the crab has a hairline fracture somewhere. This happened to one I had. No amount of tuning, cleaning/fixing re-jetting &c worked. I tried a new slide, new needle, new jets..... everything to no avail.
Of course, choke is OFF when in the full UP position.
Here's a link to the appropriate documents in my gallery:
Wow! There's a LOT more availability now then there was last time I looked!
If the carb is running rich despite correct mixture adjustment I would suggest adjusting the slide needle to the lowest setting. i.e. there are three grooves on the needle. Make sure the clip is settled into the BOTTOM one. You will need to slightly recalibrate the air-fuel screw accordingly.
What's the plug looking like? Oily/dirty: too rich; brown/powdery white; could be too lean. Somewhere in the middle like a golden pancake.... Goldilocks zone.
Check the jets for blockage. Try not to poke wire through the holes as this can sometimes enlarge them unless you're quite careful in your choice.
Where you at Little Red Devil, I have an almost identical bike I suspect so may be able to help after several years of steep-learning curves.
If you look at earlier entries in this post you will have seen the DellOrto documents and the link to UK Eurocarb who are very good with parts. Keep your eyes peeled for MA16b carbs for sale on eBay - they do come up but are rare and can be quite pricey. The correct slides are very hard to come by. Should be a 55 in the TR but I have a 50 and have to adjust accordingly.
As Dorian hinted above, it's amazing what a few small carb adjustments can do to performance. I replaced the slide spring a month or so back and the difference was remarkable. Just comparing the new spring to the old one showed how compressed it had become over time.
So..... check you have a 55 slide, D8 needle, a 6.5g float, a 260B pulveriser, a 65 main jet and a 35 min jet. If so, you're starting out with all the proper kit for the MA16. If the slide is badly worn you can consider replacing it with a slightly larger or smaller one (+ or - 5) but will have to tune out the difference on the slide needle and the air/fuel mixture screw.
Eurocarb can provide relpacements for just about every bit of the MA16b except the body, 55 slide and a few other bits and bobs. the good news is that these carbs were being used on Vespas and Lambrettas of the same period so whilst that means you're in competition with the scooter crew, they're not as rare and expensive to maintain and replace as many of the bigger carbs.
Hi, thanks for the quick feedback Sherif! I cleaned everthing on the carb except I can't find the min jet! (sorry I haven't played with carbs in a while!) how do you get to it?
The only setting difference is the float which is a 7.5 g instead of 6 g but I wonder how this can affect my problem... Basically the engine runs perfect at idle then after I put it in gear, as soon as there is a resistance against the back wheel it stalls. If I run it on the central stand then it's ok.
Oh, BTW, the mini jet is inside the lower part of the barrel, screwed into the wall at an angle. If you remove the pulveriser and the maxi jet you'll see it. To remove it you need a small electrician-sized screwdriver. Take a little bot of care cos it's small and easy to lose if you don't do it on a controlled surface. Also don't over-tighten when you replace it. Just hand-tight is fine. a little soak in petrol and compressed air through the hole if it's blocked - overwise some VERY thin wire.
I just bought the bike so worst case senario I'll take it back for check but I wanted to see if I could fix the issue myself first. As far as I gather the bike hasn't run much in the last 8 months so I'm not overly worried.
Because of this I don't have any reference point but your clutch comment was actually the first thing that came to mind. I tried it on the center stand earlier today and it runs ok at 1st and 2nd gear. No problem. It's just when you apply a resistence to the back wheele that it dies. It'll try again with all gears.
I live in a one way... Up hill so it's not giving me much chance! I started it downhill and once it picked up a bit of speed there was no problem but as soon as I has to stop I couldn't get started again. Not as nice when you have to walk 2 km beside the bike
Ok, well there' some things I can definitely help you with.
Send me your email by PM if you don't care to post it here and I can give you a .pdf of the original parts manual and a few other bits and bobs.
Depending on where you live you *may* want to consider joining the MVAgusta Club of GB.
They probably have the largest inventory of vintage/classic MV spares of anywhere in the world.
M'ship is very reasonable and you can join from outside of the UK but you MUST be a member to use the spares section.
Where are you? How about a few photos? When you have a minute, fill in some more details in the Mship section of this site. Believe me, if you hang on to the TRL then you're going to want to know some of the folk in this forum.