Hobbit won't rev

Oaky I have a 1978 Hobbit Pa 50 I. I just pulled the carb (or should I say removed the frame to get to the carb) and completely cleaned the jets etc. I cleaned the little filter. I took it (the beast) out for a spin and it starts fine but as soon as you get it going it starts to bog, lose RPM and never really get going. I mean like it gioes 10MPH down hill..and move of that speed is gravity. Any ideas? This stinks. Wardie

Re: Hobbit won't rev

choke closed?

Re: Hobbit won't rev

Larry Ward /

Joe, the choke is open. The Hobbit did the same thing when I went to purchase off of a private owner. We both thought carb was plugged. The main jet was and after cleaning it still does this. Do you think I should pull the muffler and see if there is a restriction?

Re: Hobbit won't rev

If it never ran right and there are no other clues, yeah .. check the exhaust .. That big bolt in the right side of the muffler (behind the heat shield) gives access to a tiny baffle tube.. the tube is the first thing to get packed with carbon. All exhaust must pass through that tube. Poke a screwdriver in there.

check everything related to air intake. The bikes are sensitive to too much or too little air intake.

Since the carb was plugged up, surely cleaning the carb made some difference? If not, it's likely there's something else going on unrelated to carburation.. (be SURE its clean.. i have screwed up a carb-cleaning job more than once)

ignition seems ok since it starts and idles, but ignition misfires can be mistaken for fuel mixture troubles.

Check compression.. torque the head bolts ..

I really think it's carburation but it could be many other things.. there's no easy way to diagnose from a distance.. gotta get down and check everything until you find something.

Re: Hobbit won't rev

I would check the air filter conditon and the exhaust.

Grey

Live to ride, Ride to work

Re: Hobbit won't rev

Check carb bowl drain to the right?

Re: Hobbit won't rev

Check for adequate fuel flow.

Shut off fuel tap, pull right hand chain cover, with a long skinney screwdriver reach thru the web of the chain sprocket and remove the float bowl drain plug, turn fuel tap on, see if you get a decent flow. If not, shut off tap, pull hose from tap, turn tap on. If no flow, screen in tap is plugged up. Pull tap and clean out.

If fuel flow is OK then I would agree with joew that it is probably a problem in the carb. When you had the carb apart did you remove the emulsion tube and the main jet?

Is the engine revving? Remove left side variator cover and see if it is working.

Re: Hobbit won't rev

Larry Ward /

The Hobbit won't rev, it acts like it has a governor set to come on at 3mph? I can barely get up the drive. I pulled the jet but didn't pull emulsion tube. How do you get that out? Man I'm trying to get this ready for Moped Madness and it's one thing after another. I normally don't mind it's part of the game but with Hershey less than 2 weeks away I'm running out of time. I'll clean muffler and see if anyone comes up with something. Thanks a lot for all the suggestions so far, it' much appreciated.

Re: Hobbit won't rev

Someone else asked about emulsion tube removal today .. thread is called "pa50 carb questions"

"THREAD":https://www.mopedarmy.com/forums/discuss/6/20793/20780/

I know you already answered that the choke is open.. but this sounds almost identical to a closed choke. The bike runs like crap up about 8 or 10 MPH or so.. If you disassembled the carb, check it for correct assembly. And as someone else noted (frankman) that float bowl can be installed backwards and will then cause all sorts of problems.

The drain screw on the bowl should be on the right side of the bike. This screw can be accessed through a special hole in the pedal sprocket and then through a hole in the swingarm when they are lined up..

While messing with the muffler, you might think about removing it so you can check the exhaust port for carbon build-up..

Re: Hobbit won't rev

Larry Ward /

checked the float bowl and the drain screw is on the right side as you sit on the bike. I pulled the muffler and started it up and it did the same thing, so I can assume it isn't the muffler? The tube inside the muffler is clogged with a soft soot. ';m doing my best to clean it out but basically I'm just pushing a screw driver in and out of the tube. Since it does the same thing with the muffler removed should I look at the carb? It just seems like it's hitting a rev limiter at very low rpm??

Re: Hobbit won't rev

there are no rev limiters of any kind.. The PA50II is capable of much higher speed if a performance exhaust is installed.. i dunno about the Pa50I but probably similar.

If removing the muffler didnt change anything then yeah.. look at carburation. Get the emulsion tube out and re-clean everything. (The tiniest fleck of junk floating around in the float bowl can and will block fuel by clogging the main jet orifice)

The symptom seems to point at an extreme rich-or-lean condition.. bad enough to cripple the engine.. If all else is in fair shape something is radically wrong with the air:fuel mixture.

Re: Hobbit won't rev

If you have to get back into the carb the "emulsion tube" is in the main fuel passage. It is held in by the main jet. After removing the main jet knock the body straight down against a block of wood. The tube should drop out.

Clean everything well. Make sure that the main jet is clear.

I use a set of welding tip cleaners. Starting with the smallest and working up until the next larger size will not fit. Go easy but make sure that it is clean.

Re: Hobbit won't rev

Larry Ward /

thanks everyone for your help. Wardie

Re: Hobbit won't rev

The one thing I haven't seen done was replaced the spark plug with a new one? That's the first thing that should be done. don-ohio

Re: Hobbit won't rev

Larry Ward /

Don, I replaced the spark plug , no change. See my new post

Re: Hobbit won't rev

Larry Ward /

Joew: New rings, new needle valve, carb soaked and cleaned..start it up and it does the same thing. Loads up spark plug. Previous owner gave me a carb as a spare maybe he knew more than he was telling. I put carb cleaner on the reed and it didn't leak. Man I am running out of ideas. Wifey thinks I am nuts spending all the hours on this thing. Well I am at the point where maybe I should put on the other carb?

Re: Hobbit won't rev

well.. do pay some small amount of attention to her.. but this is important! Anyway, all will be forgiven when she takes it for a spin..

i'd'a suggested you swap carbs a while back if i was aware you had a spare to swap..

The loose screws around the reed block bugs me.. tells me someone was deep inside there messing around and didn't know or care enough to button it up tight.

I'd take a real close look at things for telltales . Did they split the case? Maybe remove the flywheel, stator and everything? Mangle the carburetor's internals?

Since closing what must have been a gaping vacuum leak made no difference (??) something at least as offensive is hiding someplace.

This is just moped school. You're having fun and learning stuff that one in a million people know. Don't allow a moped to defeat you or your sorry ass will live in shame for the rest of your days.

Re: Hobbit won't rev

Larry Ward /

Joew: I'm afraid I've gotten you off track here. The screws weren't loose on the carb to reed plate, they were tight. I was referring to how easily the reed plate pulled off the crankcase after the screws were off. I thought maybe it would've been glued or something. There is no other problems with engine or crankcase, sorry I got you going in that direction. I think I'll swap carbs and go from there. When it loads up it feels like a govenor is stopping the bike. Man what a pain. I'm going to get it running real good and sell it at Hershey. Or maybe trade it for a Tomos Targa or something.

Re: Hobbit won't rev

ok.. im up to speed.

I came across one reed block that was sorta stuck on and i had to be careful not to tear the blocks rubber seal when prying it off.. but most times it should pop right off.

Permatex 2 will provide an excellent seal without any risk of adhesion and damaging gaskets or whatever when disassembling parts.

Good luck with the other carb.. you have a new float needle which is great... I'd probably install it regardless during a quick examination of the 2nd carb.

Re: Hobbit won't rev

Ok I have worked and owned on hobbits before. I also had the same problems that you were having. Ok first you should clean your exhaust or get a new one. Then just remove the air filter and the plastic tube holding it in. This will not hurt the engine b/c they have a huge jet in the carb. Make sure the brakes are not dragging and the tires are pumped up. A new sparkplug will also help a little. Make sure your drive belt is tightened. If you do this I am positive your hobbit will gain speed.

Re: Hobbit won't rev

Larry Ward /

Joew: I swapped the spark plug cap on the advice from a friend and it didn't change anything. Oddly enough though I shut of the gas valve (my new $45 valve!) and when the carb starting running out of gas it actually revved higher almost full throttle? What's up with this thing?

Re: Hobbit won't rev

that's normal.. and something the power hungry tuners should take notice of. The real power is right at the edge of too-leanness.. Admittedly it's a sharp edge and engine damage is on the otherside, but imo most people aren't even getting close..

When an engine leans out the mixture burns very fast and hot and provides a lot of power .. a bike might actually lurch forward a couple times when running out of gas on the road.

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