MOPED ARMY

Probably has a little to do with the fact that you're using a short conrod. Not sure if those cyls are setup for D or ABC cranks.... but you'd have more compression with a long rod D crank - chikabowow ;)

You should have a chocolate brown color to the plug... my money is on jetting... but you should check your timing and compression too. Buy a jet range and get it over with... there is no magic jet calculator... JUST BUY SOME JETS BRAH.

Also, I love you already because you got rid of the POS bing carb... so you're on the right track.

What's your compression?

What's your timing?

If you don't know what those are, go search for "compression" and "timing" in the wiki, do it and post the results.

Both of those are important - don't say the timing is stock - that means nothing.

You shouldn't need to change gearing... the 11x44-45 gearing on those bikes is pretty low for a pipe and carb (the athena 50 cylinder is basically a little better than the D cylinder) you should be gearing up - AFTER you figure out what's up.

I did 38 on an A with gearing pipe and carb once, but the take off sucked... Keep at it... you should see at least 42 out of that setup with a 13t up front... probably more if you're getting to 35 and the tuning sucks. (edited)

It'll raise your compression noticeably and yah... that's what you'd want. I'm not really sure what you're wanting out of your setup...

I would continue tuning... I don't think you have all the performance out of that setup yet.

If you do decide to go the D route, I suggest buying a whole other bottom end, because unlike Puch, all sachs cranks already have a small end needle bearing. However, it wouldn't hurt either. For $135 though I'd imagine you could get yourself a whole other engine.

What do I need to take into consideration when installing a D crank in the 5051a? With the slightest of slope my bike will not accelerate. It'll run 5-10mph until I pedal the hell out of it... Im guessing its a compression issue...

We have the opposite problems. I wish I had your problem though. Also get a timing light instead of the volt meter trick its much easier see your timing. Well worth the $40 if you have a lot of mopeds.

ah... so I thought the slow acceleration was from compression on the bottom end, but at higher rpm was good. I guess if compression was bad the bike would run poor in both ends of the spectrum.

So timing light, and some tuning... Hope I can figure out that timing light.

thanks for the responses

Ok so I tried setting the timing, or points rather and Im stumped. I have TDC, and fire point, but i cant get the stator plate to budge. took out the three screws....this maybe a "duh" question, but am i suppose to take the flywheel off?

thanks

I did. But I really cant get it to rotate, is there a trick? am I trying to rotate the wrong thing? (im putting pressure on the the metal that the screw comes into contact with on the stator plate). maybe its just so old its need some extra force. it looks to be in great shape though.

Update...still no acceleration. I really haven't done anything new besides timing. in fact I had to advance my timing to the point where the stator plate could not rotate anymore without covering up the three screw holes. so Im still off some degrees. Maybe the 15mm SHA is too rich on idle/ acceleration? though the plug chop is where it needs to be. Any thoughts on a 70cc kit giving more bottom end power vs a 50cc athena?

Does everyone else with a 5051a have crap acceleration like me??