1979 honda hobbit pa50 custom

Michael Phipps /

Okay, so I'm relatively new to mopeds, but I find they are way cheaper than aircooled VW'S . So i get to spend less money and still enioy working on aircooled engines. I'm no expert by any means and I'm always learning and listening. With that said I've decided to build a really nice, powerful hobbit engine.

My youngest son and i have always tinkered on VW's and Subaru's. This will be one of our last projects before he leaves for USMC boot camp in September. Any help, advice or constructive criticism hs welcome.

Here's what I'm working with;

1979 Honda hobbit pa50II.

honda hobbit carb UPGRADE pack - vm20

https://www.treatland.tv/honda-hobbit-carb-UPGRADE-pack-vm20-p/hobbit-carb-pack-vm20.htm

Honda PA50 Hobbit, Express Athena 73cc 47.6mm Cylinder Kit

http://www.mopeddivision.com/honda-pa50-hobbit-express-athena-73cc-47-6mm-cylinder-kit/

DOS SIX ROLLER VARIATOR FOR DERBI AND HONDA MOPEDS

https://www.doscycles.com/collections/honda/products/dos-six-roller-for-derbi-and-honda-mopeds?variant=47889911695

HONDA HOBBIT/CAMINO RACE CRANK

https://www.doscycles.com/collections/honda/products/honda-hobbit-camino-race-crank

MOPED FACTORY HONDA HOBBIT BIG FIN 47MM HEAD

https://www.doscycles.com/collections/honda/products/moped-factory-honda-hobbit-big-fin-47mm-head

Thanks again! I've learned a lot from this forum.

-Mike

Eatonville WA.

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Re: 1979 honda hobbit pa50 custom

Michael Phipps /

On the bench

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Re: 1979 honda hobbit pa50 custom

I always like hobbit tanks like that.

I gotta do one of those someday.

You can run them close to empty with a tall carb off the intake.

But you should put in a new lower fitting in the tank. That would be a good thing (edited)

Re: 1979 honda hobbit pa50 custom

U are gonna want that h95 hobbit pipe. assuming it will fit your bike.

Nice list of parts, case and gasket match that cylinder, dont leave any power on the table or you could get dusted, just ask my brother.

Re: 1979 honda hobbit pa50 custom

good call, don't forget to order some longer studs to work with that big fin hobbit head.

some people weld or epoxy the cases to ensure a good seal to the athena kit transfers

and 100% you should run a head temp gauge. i think a retarding cdi, either the HPI or a 'oem style' stator with a jog scooter cdi box, is necessicary if you do go with the big dude pipe. you might be able to get away with points using the proma, just by closing your points gap to retard the ignition, but you'll be leaving a lot of performance on the table.

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

Re: 1979 honda hobbit pa50 custom

game on, that's a solid build. I think you're nailing it. jam on. as you get deeper in there's tons more to mod, rear pulley being another pretty important one but you got enough there to do lots of going much quickly.

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

So I have had a heck of a time splitting the case with the Phillips head screws. I soaked them in PB Blaster, bought and tried an impact tool to no avail! Finally decided to drill out the heads! Any advice on further splitting the case is welcomed!

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Re: 1979 honda hobbit pa50 custom

Trust me, heat them up with a propane torch. Also the bit is key!!!! Not just any phillips, it has to be the big one with the flatened head. If the bolts hot enough and the impact driver is strong, it will twist out, dont twist those head off though. U can get propane refills at convenience stores, just need the tip. Zoom in to pic and proper bit in pic (edited)

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Re: 1979 honda hobbit pa50 custom

Impact screw driver. The kind you hit with a hammer. Everyone neeeeeds to own one for this kind of thing.

If you strip them, it’s ok. Just drill the head with a big bit. Then use a little pipe wrench or locking pliers to remove the shank, or “stud” after the case is split.

Re: 1979 honda hobbit pa50 custom

It's deja vu all over again with the PA case and screw difficulties lol. But really, these are such a pain in the ass; on another recent thread i reccomended swapping out all the screws for sockets - makes life a bit easier on subsequent teardowns.

And nice build so far. I'm using the same Athena on my current project; made a thread about it a few weeks ago.

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

They wouldn't budge, even with the impact tool. Drilled them out.

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Re: 1979 honda hobbit pa50 custom

Ungapped rings to bind them all /

A 2 point puller will work, easier to center on the case than a 3 point.

Re: 1979 honda hobbit pa50 custom

It’s too late now, but get a Japanese Industrial Standard cross-head screwdriver, or JIS for short. I use my JIS #2 on all Phillips head screws. You can find them on Amazon. American Phillips head have rounded inside corners and were designed to “Cam out” rather than break the head off, something to do with machines on assembly lines I believe. The JIS has square inside shoulders and a different profile and I find works better on all Phillips type screws. if you ever work on an old Japanese motorcycle one of these screwdrivers will save you a lot of headaches.

Re: 1979 honda hobbit pa50 custom

thanks tate, thats a really good point. agreed the cam out on standard phillips is a real motherfucker and the JIS is a super huge headache saver.

Re: 1979 honda hobbit pa50 custom

yeah i bought a 'vessel impacta' a few weeks back and its above and beyond the best screwdriver i've ever owned. it has built in impact, but you don't need it, it grabs bolts so tight.

i bought a #2 but i think the hobbit case screws are a #3. dont have any hobbit cases handy.

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

Here's the impact I bought, the hobbit laughed and I think I heard it say, "none shall pass!"

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Re: 1979 honda hobbit pa50 custom

I've had to drill out those heads too when I used the right screwdriver but the metal was just like putty.

It's no big deal. Allens are better anyways.

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

On a side note, while waiting for parts to arrive I decided to wrap my exhaust with some left overs I had. Would be interested to hear peeps thoughts on wrapping an exhaust. Advantages / disadvantages? (edited)

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Re: 1979 honda hobbit pa50 custom

Michael Phipps /

"No Hobbits shall pass!"

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Re: 1979 honda hobbit pa50 custom

Promas can become reasonable sounding pipes with wrap and a better silencer. The wrap really helps though

Re: 1979 honda hobbit pa50 custom

The wrap and a Ktm 65 baffle really cut down the noise with my proma.

Re: 1979 honda hobbit pa50 custom

any effect of the wrap on temps? It's gotta keep your pipe identifiably warmer, but being still well below appreciable radiation, the heat from condunction off the inner surface i wouldnt expect to have any effect at all on the gas going through it, especially on the time scales that gas is in there. I mean you've got a fraction of a second residence time.

Never thought about noise, just never thought about it. makes sense.

I never liked wrap because it cost some additional money and can help keep water on and accelerate rusty

but it does have the advantage of not scorching your leg when you idiotically lean your calf into the chamber.

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

All wrapped up

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Re: 1979 honda hobbit pa50 custom

Michael Phipps /

Pulled the case apart, was pretty easy. Interesting that the Phillips head screws where loose after the case was apart. Just unscrewed them by hand.

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Re: 1979 honda hobbit pa50 custom

Michael Phipps /

Yeah, the head and cylinder are just a bit bigger! Compare the original head with the new one in the second picture. (edited)

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Re: 1979 honda hobbit pa50 custom

Michael Phipps /

Since I'm changing out the crank should I replace these bearings since everything is apart? I've checked its tolerances and they are perfect. No wiggling / movement any direction. Seems like a pain to take out.

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Re: 1979 honda hobbit pa50 custom

Ungapped rings to bind them all /

Bigger pain to have to go back in after all that work! Change 'em while its open. Available at Honda parts locations and Treats.

Re: 1979 honda hobbit pa50 custom

i still have a stack of those bearings cuz last time i ordered some i got like 25, still got probably half left.

worth doing, but get good bearings and check the RPM ratings. it'd be a shame to not replace it when you've got the easy opportunity, but it'd be a bigger shame to replace them with crappier bearings that fail when the OG ones were totally fine...

Re: 1979 honda hobbit pa50 custom

Michael Phipps /

Will do! The shop manual isn't really clear on their removal. I can press the new ones in, but any advice or tips on removal is appreciated.

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