Getting my Hobbit up to Par

hey everyone.

Yes I read the wiki, and have read into a lot of helpful advice, but I'm still looking for some more personalized help... So here it goes:

I'm trying to increase the performance of my bone stock '78 Pa50-II. Not looking to go 50, just want to get it tuned as well as possible with a stock setup.

right now it will go about 26 mph tops on level ground. 30 down hill.

I just torched/ decarbonized my exhaust yesterday, I couldn't really tell all that big a difference.

I'm not sure, but I think I may need a new drive belt...

my current one is the stock Mitsuboshi. It's adjusted all the way out. Is the belt supposed to have some good tension to it? As it is, it meets the requirement of being 2mm into the rear variator as the manual says, but I can easily squeeze the two sides of the belt together. I measured it and it's 42-1/2" long, and I thought I read it was only supposed to be 41". It squeaks sometimes on takeoff also, and there is black belt dust all over the inside of the belt cover. My guess would be that that's a bad thing...

I'd really love to go get a new belt from honda, but I'd also really love to not spend $80 on a belt.

Has anyone had any luck with other belts?

Also, If I'm going full speed/ full throttle down hill I hear a sandpaper like sound. Not sure what that's all about.

I've put 100 miles on this moped over the summer, and haven't had any problems with it, she runs like a top...

there are some weird things though.

It will absolutely will not start without the choke on. It also won't start without use of the decompression lever.

If I hadn't read about others' experiences on here, I would think it's normal, but most people have little problems starting their hobbits. It usually takes me 2-3 tries to start from cold.

If anyone has experienced any of these problems (or quirks) your input is greatly appreciated

...oh, and though I like my tomos for it's speed, the hobbit is still a way smoother, better accelerating, and more stylish ride ;) If only it would keep up with traffic

Re: Getting my Hobbit up to Par

find an expansion chamber, get a new belt (i use the dayco #17415. not the best but it works), upjet and you'll notice a huge difference. just the expansion chamber alone gave me about 7mh on the top end. dont forget to upjet, i soft seized my PA50II after throwing my expansion chamber on in about five minutes. no joke.

if you want to get crazy, mod your variator i'm doing that right now. just took a little break to smoke and search the interweb.

Re: Getting my Hobbit up to Par

thanks for the advice, but I'm looking to get her running at peak performance with an all stock setup.

after I do that maybe, just maybe, I'll look into some aftermarket performance

Re: Getting my Hobbit up to Par

It sounds like for some reason your bike is running too rich.

Have you cleaned the air filter? Also check the little three hole air inlet under the rear of the left foot plate. Critters like to make their nests in there.

Like daveysaves said the best thing you can do is get an expansion chamber but therein lies the problem. The Proma factory is out of business and the stocks of new Proma Circuit piped has dried up. The Leo Vince factory was offering a basic copy of the Proma pipe but if I am correct they have sold out all their stock and will not be making any more.

You can graft on another pipe of some sort but you will have to get a donor stock muffler and cut off the manifold and weld it on to the new pipe as the Honda connection spigots up into the cylinder.

Re: Getting my Hobbit up to Par

Honda had to slow some bikes down to meet state requirements, but re-engineering a bike to go slower is not relay Honda thing. so what they did in some cases was bend the stinger on the exhaust. crude i know, but effective non the less. chances are if you have a bike from Ohio, Indiana, or any of them other strict moped states, you have a bent stinger.

Re: Getting my Hobbit up to Par

If you have to start with the choke on then you are likely not too rich. Requiring choke to start is not a bad thing.

Lots of things could be slowing you down. Bad wheel bearings, dragging brakes, variator may not be opening all the way. It is always the best policy to get a bike running really good before adding performance parts.

That being said. If you can find a pipe then that is the easiest way to get more speed from a PA50. Since pipes are hard to come by for the PA50, you may have to hack something. If I wanted a pipe I would tecno circuit and cut and weld a header to match:

Another pedder in here had great success doing that on a honda express.

Re: Getting my Hobbit up to Par

what is the powerband like on those circuits?

Re: Getting my Hobbit up to Par


thanks for the tip

my muffler tip was bent, I opened it up, but alas, no noticeable difference.

Earlier today I made an attempt to remove / clean my carburetor. Man, that was a bitch.

I got the engine separated from the frame, only to find out that my screwdriver can't get a grip on the semi-stripped screw heads on the intake manifold. I decided it was time to just leave good enough alone.

Maybe another day I'm feeling more ambitious and have a screwdriver with a larger head, my carb will get clean.

Of course, I'll also need to take my carb out if someday I upgrade my exhaust.

That techno circuit looks like It would be great adapted to a hobbit.

Re: Getting my Hobbit up to Par


Re: Getting my Hobbit up to Par

good tip jeremy,

will definitely do that next time I've got my ped apart. (she's already back together, not as big a hassle as i thought it would be)

Re: Getting my Hobbit up to Par

Raymond Rexroad /

Honda had to slow some bikes down to meet state requirements, but re-engineering a bike to go slower is not relay Honda thing. so what they did in some cases was bend the stinger on the exhaust.

my muffler tip was bent, I opened it up, but alas, no noticeable difference.

I can only speak about Hobbits here - the bent muffler tip does not restrict the exhaust flow in any way. I've cut open a muffler, and their is a smaller restriction deep inside there - much smaller than a bent exhaust tip.

I also thought that the tip being crimped had a negative affect - up until the day that I cut apart an exhaust and found a smaller pipe inside of it.

Re: Getting my Hobbit up to Par

RJ, if you havnt had your carb off and cleaned it yet you really should. A bitch the first couple of times but it becomes a lot quicker the mroe you do it, it could cure your top end problem a little and also make it easier to start.

RE: using the decomp to start it wont make any difference to whether it will actually start, it just makes it easier to start pedalling. The egine will still start if you dont use the decomp it will just be harder to pedal.

I dont know what the mileage is on your bike but when i got mine (had about 6000 on the clock) the exhaust port was absolutely clogged with carbon. So, its worth taking the head off and having a look down in there. That would definately hurt the top end.

Re: Getting my Hobbit up to Par

I have a pa50I and sometimes when I was riding it, it would only go about 15 mph...then if I hit rather large bump or hopped of a curb, it would all of a sudden go up to 18-20 mph. Well yesterday when I was putting on my ramp plate from the pa50II, I noticed there were little metal clips that held the weights. Not really sure why they were there, but I bet that they were catching my weights and not letting them slid out...but when I hit the bump it would knock them free. I didn't put the clips in as I really can't see why they are there. That might help you out maybe if you took those out?

Just a suggestion.

Re: Getting my Hobbit up to Par

my bike's got 800 miles on it

The thing with the decompression lever on mine isn't that it makes it easier to pedal, but that it absolutely WILL NOT START without it. The only way I can get it to start sputtering to a start is with the decomp lever.

I'm definitely going to clean my carb... eventually.

Has anybody here tried the cleaning method the manual shows, using compressed air and keeping the carb on the frame?

Re: Getting my Hobbit up to Par

If you must use the decomp that is a good thing. That means that it has so much compression that you need the decomp to turn it over. The decomp just makes it easier to turn the engine over by lowering the compression. It would be a sign that you have less than idle compression if you could start without the decmp.

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