MOPED ARMY

It's not the screws man, It's the jetting. Pull your jets, post what they are and somebody will let you know a good starting point.

trust no one but yourself

Okay have the compression fixed. Put all new seals. Bike started right up. I have it idling good but it wants to die as soon as I give it any throttle. I believe too rich but I’m not smart with carbs. Doesn’t seem to make a difference with choke on or off. If I give it throttle extremely slow I can get the rpms up some but still will not allow me to really get it up and running. Any help is appreciated. Should I pull jets out first and see what is in there. The brass mixture adjustment screw what way does what on this. It doesn’t seem to make much of a difference when I’m moving it. I’ve only made small adjustments though.

If still using that 20 Dellorto PHBG you need to know what parts you have in there in order to tune. Disassemble and make note of:

Main Jet number

Idle Jet number

Starter Jet number

Needle number

Slide number

Atomizer and Bushing number/type

numbers sound usuable and should be able to rev up. What sound strange is your choke has no effect, I've seen it where the plunger doesn't seal up on the tip, make sure it goes all the way down.

The w2 needle has a small tip, u want something with a big tip, the 2 stroke atomizer and bushing.

u can try dropping that needle all the way down and screw the idle adjustment screw all the way in, both to lean out your off idle low end but take a peek at your choke first.

also, did the reeds look good and did u put the piston in the right direction?

Arrow on the piston crown should point to the exhaust . The direction of flow .

Well now I’m second guessing if I didn’t screw that up. I’ll see if I can pull the spark plug and take a peek without pulling the head off.

What exhaust pipe are you using? What air filter?

Okay back at it again with this beast.

I have checked the choke. It is operating correctly and sealing. I did play with it more and when I turn the choke on it increases the idle and I can get closer to being able to rev up. It still Boggs down at around 1/3 to 1/2 throttle.

I decided to start back at the beginning with checking timing. I verified tdc and gap is perfectly in spec. I got a timing light though and it is firing almost too the tdc mark. Well past the fire mark on cover. I don’t see any way to adjust this? Could this be contributing to my issue. It is firing between fire mark and tdc mark.

This thing fires right up with just 1/2 a pedal every start and idles great though. Just get get much past that.

Finally got parts and have been trying a lot of different things with no positive outcome. I’m lost as of where to go from here as I still think it’s carb setup but would think by now it should be able to at least get this beast at more than an idle consistently.

So to recap it’s a 79 hobbit pa50I. Dr 70cc kit. Proma cuircuit pipe. PHBG 20 carb.

I just checked timing again. It’s a hair before the stock fire line and points gap is good.

I just checked compression again now I’m getting 112psi with a cold engine, so a little low PWR the manual but shouldn’t affect it much right?

Originally the carb had

88 main

40 idle

60 choke/start

4 stroke atomizer bush

260an atomizer

30 slide

W2 needle

With the above carb setup it would fire up with a half pedal every time and idle great. Once I started bringing throttle in around 1/8-1/4 it would bog down and die unless I let off throttle quick. I believe it was rich at idle and lean at throttle but I’m not smart at this stuff.

I ordered some parts and have tried a combo of things that I have not progressed much past the above and now doesn’t idle as good and Boggs down immediately at throttle. Plug looks very rich. Also now only likes choke on.

Currently have

97 main

40 idle

60 choke / start

2 stroke atomizer bush

262au atomizer

40 slide

W7 needle set on second clip down.

I have main jets 88, 90-110

30 and 40 slide

W7 and w2 needle

2 and 4 stroke atomizer bush

262au and 260an atomizer

Parts to play with now and if anyone thinks I need to order something different to try I will. I just don’t want to keep throwing money at this guessing.

Let me know if anyone has any good ideas

I’ve also checked for air leaks as much as I can at idle with carb cleaner by crank seals and all intake areas with no changes in idle.

I also have stock carb I can throw on and try I will prob just have to order a larger main jet correct? I also don’t have the stock throttle cable so would have to get one too. I think that’s where I’m heading unless anyone chimes in with other ideas.

Thanks

Jake

Any ideas where to go from here.

I am running a mikuni right now and in the exact same boat. I have it idle fine, if I creep up the throttle I can get some momentum, but it definitely bogs and dies quick at WOT. My numbers wont be anywhere similar but the results of this will help direct me in my tuning.

Please keep sharing the progress sir!