PA50II Air cleaner element...

My hobbit doesn't run at full speed unless I pull the air filter out. So, I got a new filter except this one is for the new pa50 model so it's "T" shaped and a different kind of sponge. I Cut it to size, soaked it in 2 cycle oil, squeezed the excess and it still doesnt run at full speed. (I bought the new air element after alredy cleaning the old one and having the same problem)

any suggestions?



Re: PA50II Air cleaner element...

i have the older bike with the straight foam element. My bike won't run well if the element is _out_ . But with the element installed, it runs great. Your bike seems to be starving for air. Are you sure the entire air box is clear? No bee hives in there?

The element, or the lack of it, has an effect on the richness/leanness of the fuel mixture. But there are other things that effect mixture.

These bikes were built to run properly with the element installed. If you installed a new element, close to the original factory element, and it won't run, look somewhere else for the problem.

For instance, does the choke plate open completely or is the linkage messed up? A partially closed choke will restrict air intake.

I know you can't actually see this choke plate without dropping the engine and removing the carb and looking in there.. So, leave this as a last resort. Do take a close look at the external linkage.

How many miles on this bike.. Is this condition a new development or just part of the continuing restoration?

Re: PA50II Air cleaner element...

This is a new developement, how do I clean the air box? I just recently cleaned the carb and the choke seems to be fine. The bike runs w/ the element out but is slight;y louder (obviously) and has full power. As soon as I put the old straight element in or the new modified T element in, the bike just bogs out. I'll check more of it out tomorrow .



Re: PA50II Air cleaner element...

i dunno how to clean it out.. the freakin thing is impossible to get into.. Just pull the filter out and look around with a flashlight.

One part you can see and clean is the air-intake tube. Air is supposed to enter that box ONLY through the 3-holed rubber extension/tube sticking up on the front left side of that box. If one of those little holes is clogged up with mud or a big dead cockroach, air supply to that engine is cut by 1/3 .. The holes must be open. Look in with the light and stick a pencil in them.. see if a previous owner lost _his_ pencil down there..

Or, pull that whole rubber arm right up and out of it's hole. You'll have to pull hard and wiggle it. NOTE! Getting it back in while the engine is up in the frame is pretty much impossible .. there's no room for hands to get in there. You must lower the engine and replace it.. (although i never tried running without it.. might work ok but too much air may be allowed in..

Re: PA50II Air cleaner element...

Hello out there,

I just got a 1979 pa 50 with 233 miles on it. How do you get the carb off? (I have sachs and puch's) The carb looks like its in a jungle of welded metal frame?

Thanks, Ray

Re: PA50II Air cleaner element...

The engine must be lowered from the frame. Notice that the engine is bolted to the sheet metal swingarm.. when the rear wheel goes up and down, the motor pivots with it.

The engine is free to pivot because it is attached to the frame by a single large bolt and nut. Remove that bolt, retract the center stand, and the engine / swingarm can drop to the floor. Once on the floor, the bike will balance precariously on the muffler.. Now the carb can be removed by unscrewing the 4 screws that mount the carb and intake manifold (as a unit) to the engine block. Then the carb and manifold can be seperated.

A few cables, wires and hoses prevent the engine from just dropping down. These must be disconnected to prevent stretching or breaking something. They include the decompression cable, the fuel line, the throttle cable, the rear brake cable, as well as a few electrical wires. The spark plug wire might be another one, depending on how it's routed. Some of these are attached to the engine (like the throttle cable) and some are just routed through or around the engine or frame in such a way that they interfere with the operation. Some are clipped to the swing arm.

To drop the engine, first disconnect everything that appears it might interfere . Remove the nut on the pivot bolt. Have someone hold the bike steady and, while holding the engine up with one hand, retracted the center stand with the other. Now pull the pivot bolt out. The engine is now free to fall. Lower the engine just an inch or two and rest it on blocks of wood or something (prepared ahead of time). Now look closely and see if anything else needs to be disconnected..

Once everything is ready, slowly lower the engine to the floor.

This description may sound like a lot of work and it is the first time you do it. However, when reinstalling the engine you can push it up into position _first_ , lower the center stand to support it and stick that pivot bolt in.. and _then_ re-route your cables and wires and hoses in such a way that they (most of them) will not interfere with dropping the engine the next time.. With the way my bike is now set up the whole operation takes only 3 or 4 minutes.

Accessing the carb several times is usually necessary when fixing fuel problems or during the initial hospitalization of a junkyard-jewel.. Making it easy by rerouting all that stuff is worth the effort.

Re: PA50II Air cleaner element...

Thanks so much! This web site is the only way I will be able to assemble my fleet of various peds. (it strains my marriage)I think it is safe to assume that you may need 4 or 5 to have 1 or 2 running good at one given time!


Re: PA50II Air cleaner element...

It is a LOT easier to remove the two bolts holding the rear shocks and lift the rear of the bike and leave the main engine bolt in. I have done it both ways. Be careful to not strip the intake screws!

Re: PA50II Air cleaner element...

here's a description of the rafter method, courtesy of ped58.

There is a bit more to it than just the rear shock bolts.

I don't have a convenient rafter or anything else up above my work area so i'm not partial to this method.. Try it and see whats best for you.. You might find an even easier method.. If so, please share it.

I have three PA50 frames and am slowly designing and assembling a customized bike. One of the customizations will be easier access to the carb..

Re: PA50II Air cleaner element...

Here's another description of the method, by Fred.

Re: PA50II Air cleaner element...

Well, I dropped the engine and pulled the 3 chamber air intake tube. Everything was clear. The little I could see of the air box seemed to be clear. So what now? Now that I have the engine dropped (pain in the ass) Is there anything else I should be checking? Why isn't my bike getting air?



Re: PA50II Air cleaner element...

Unless you modified something related to carburation, i don't know what the problem is..

Air supply to the carb is a pretty straight forward thing. But i don't let my guard down just because something is simple. That attitude can cause me to overlook something so simple and obvious that i feel foolish after i find the problem..

You got the engine down so look at the choke linkage. Does the choke butterfly open fully? I mean does it open far enough to be in an absolutely straight line with the bore? Does the choke linkage have all it's parts and springs so it opens without question whenever the lever is moved?

How about that short rubber hose that connects the carb to the air box. Is it crushed? Does it mate properly with the hole when the carb is installed? Is it there at all? On my bike this gasket/hose was crumpled and wasn't inserted properly into the air box.

if i think of anything else, i'll post it.

Re: PA50II Air cleaner element...

Well, I've come to the conclusion that the air filter and carb are just fine. I almost get full speed but it bogs out sometimes. You can feel the power cut out and then on again. Almost like someone is flippong a switch on and off. It tends to backfire more than usual too. Are these two signs of carbon build up? And what causes backfiring when I am at a high rpm and I lay on the brakes? As soon as I let go of the brake it will backfire. My bike is almost there, I'm so close!

thnx for the help



Re: PA50II Air cleaner element...

carbon can do it.. so can the thread of a sparkplug if it extends into the combustion chamber.

a little piece of carbon glows red hot.. you close the throttle.. a small amount of fuel still enters the engine from the idle circuit and this fuel may be ingited by that piece of carbon at any time, perhaps when the piston is near the bottom of it's stroke. Result is a backfire.

Hve you checked for vacuum leaks between the carb and engine? I ask because it's just another thing that can cause erratic performance at any rpm.

There's a good chance that more than a single thing is contributing to the less-than-perfect performance, but you are eliminating them all, one at a time.

Re: PA50II Air cleaner element...

no, how do I check for vacuum leaks?

thnx again,


Re: PA50II Air cleaner element...

one way is to get the engine running at a nice smooth idle and spray Starter Fluid around the carburetor's manifiold area.. If some of that stuff gets sucked in through a leaky joint, the engine RPM will rise for a moment.

The preventative cure is to use new gaskets when mounting that carb back on the engine.. or use the old ones with a non hardening gasket sealant like Permatex 2, on all mating surfaces.

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