cant keep my hobbit running

Well ok. I get this project 1978 Honda Hobbit that this guy states runs. we get to his house to pick it up and it does idle. So tuning this and that and cleaning the carb ( its been sitting alittle bit) and check spark and timing and such we try to fire it. it fires, but it has very weak power. so i try to ride it and about slow as a dead horse i get one house away and it stalls. we play around alittle more and some days it gets to 20 ( top speed) and i can ride it but cant let it stop or it will stall. we got a working carb for it and the problem isnt solved...and suggestions for my moped to idle and be rode worthy. thanks...any parts i could be missing?...

note* we have a make shift petcock on it...would the OEM help?

Re: cant keep my hobbit running

Beyond the possibility of some tiny piece of crap in the float bowl (these things are really sensitive to dirty carbs) that will partially block the main jet, check for exhaust restriction.

Remove the muffler and look for carbon build up in the port and header.

Remove the right side heat shield on the muffler. There's a large bolt screwed into the muffler. Remove that. Right inside that hole is a tiny baffle tube that ALL your exhaust gases must pass through. So, stick a screw driver into the hole and feel around and find the tube.. then clear it out if it's packed with carbon.

I found a junkyard bike and it's little tube was packed .. only a tiny passage remained.

See attached pic.

If the exhaust is clear, the carb is dirty ..


Re: cant keep my hobbit running

Nick Hughes /

hey thanks alot. ill have to try that one out because it cant be the dirt in the carb...we are thinkin like float problems. thanks again

Re: cant keep my hobbit running

well.. there's lots of stuff besides dirty carb or exhaust that can seem to cause "very weak power" .. whatever that means. Something like a slipping drive belt or variator troubles.. or dragging brakes or who knows.

If you suspect carb trouble, these old bikes do tend to develop vacuum leaks around the reed valve/intake manifold gaskets. If you supect flooding symptoms like from a high float level, also check for intake air restriction. The air filter access is a small, 1x2 inch plastic thing mounted flush on the left side swingarm near the pedal crank.. People have found rat's nests and beehives inside that metal air box..

you mentioned 20mph as top speed. Is this a PA50I with an expected top speed of 20mph or a PA50II (30mph)?

A few more details about the bike and a better description of the symptoms might help.

Re: cant keep my hobbit running

Nick Hughes /

ok...well ya i know the top speed of a pa50I is 20...and ive only had 20 like a few times...the symptoms seem to be 1)not getting it to run at all or 2)if it does run not being able to idle. ive never worked with 2 stroke engines and dont know reeds or the such. so what should i look for in a good working reed cage?...ill go clean the exaust out now...thanks

Re: cant keep my hobbit running

The idle problem seems to point at the carb.. air or fuel supply or float or something. However, vacuum leaks can do it. So can loose head bolts. Use a small sensitive torque wrench and check for about 10 pound feet of torque.

Make sure the decompression valve in the head is sealing.. check it's cable adjustment and check for carbon or crap on the valve's seat.

Get the thing running and spray some Starter Fluid around the manifold. If engine RPM reacts, a vacuum leak is sucking some of that stuff in. Fix the leak.

Reeds need no maintainance. Take the carb/intake manifold off and carefully pry up the reed block around it's edges. Don't accidentally scratch the rubbery reed petal sealing surface with the tip of the pry tool. Just take a look at the condition of things.. If the petals are intact and no signs of cracks and the rubber seal under them is ok, and the petals lay flat.. and the petal lift limiting stops are in place, things are ok.

If you ever remove the petals for some reason, be sure to use blue (removable) LokTite on the screws on reassembly. If the screws vibrate loose you might end up buying a new engine.

On reassemply coat the mating surfaces and gaskets on the reed block / intake manifold with a thin coat of Permatex 2 (non-hardening gasket sealant.. don't use any sort of gasket adhesive or hardening gasket maker). These joints are especially prone to vacuum leaks.

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