Boredom Really Sucks.

Reeperette /

Having a choice between sitting here, and possibly takin my Trike out onto the golf course for some "fun" and seeing whether the complex maintainence crew or my girlfriend kills me first - I figured I might as well sit here.

It'd be a shame to damage the Trike.

Been lookin into something that I've been pondering a while, and I am firmly convinced now that you could put a 70cc three speed automatic (CT70) engine on most moped frames.

If yer nuts enough to try, have a looksee at this one.

I am filing it as a future project idea myself, but $$$ is kinda tight right now fer me, house and all.

On a Tomos frame, if you bolt that thing to the 2nd and 3rd bolt holes, it just might very well fit, looks to me like it would, anyhow.

Just some idle thoughts.


Re: Boredom Really Sucks.

chuck russo va /

that on any bike is a sweet idea, 4 stroke, 3 speed. and that motor is bullet proof almost, my friend had one, we beat the heck out of it day after day and it never once died on us. and always started in 3 kicks

'Sleeper' motors.

Yeah .. sneaking a bigger motor into a moped frame would be great .. if the cops never think to make something of it

But there's another 'problem' with your plan .. the small Honda 4 strokes are having a resurgance of popularity with old farts who are driving the prices to ridiculous levels ... some of these guysa are buying 30 year old CT70's for $3000.

Now thats stupid in my mind....... but ... ??

(I mean Honda could make brand spanking new ones for a cost of probably $300 or $400 apiece)

I've been wondering whats going to happen when some cop eventually takes an interest in my PA whizzing along at 50mph .. whats he going to say ? .. What's he going to do ?

I would guess MOST of them will be amused .. "How the he!! does that thing do 50 ??!!" .. (with a grin creeping onto his face as he looks it over .. I mean he just clocked me .. its not a 'claim' of 50 .. its real - he just saw it)

But there will undoubtably be a percentage who will be offended ... and think my 50mph moped is the most evil thing threatening the free world and democracies on the planet.

And will make something of it.

A lot of that caN be prevented with 'stealth' riding habits.

(by not flaunting it and obeying all the smaller rules)

Sooner or later though .....

Re: 'Sleeper' motors.


JINCHEN, a CHINESE company bought the dies from HONDA for the TRAIL 70 and TRAIL 50 and are remarketing the scooters and motors under the name PANDA Fun Rider and TRAIL 70.


Re: 'Sleeper' motors.

Here's the pic, sorry 'bout that


Re: 'Sleeper' motors.

yeah I know .. I have posted pics of them here several times.

And a local dealer I talk to regularly .. sells them .

And check this out .. the Jincheng Knight (the same Honda pettern motors)... 50cc 4 stroke 3 or 4 speed tranny and front disc brake and and telescopic forks and chrome and all .. looks a lot like a small Magna or something... are legal as Mopeds here in MI !

I've ridden next to two of them in the last year right on the street .. riding in traffic with the cars.

Moped sticker only .. no insurance or plates.


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Joe .. do you have any old QT50 pistons you could measure some details on ?? ... for me .. (looking for a 'swappable' piston for my PA)

Re: 'Sleeper' motors.

lol the cops probly gonna say.....''wtf?!?!?!?!''

Re: Boredom Really Sucks.

go ride the trike... man

Re: 'Sleeper' motors.


Yeah. I have a brand new 1x piston and ring set and a couple of older original pistons I can get some measuremnts from. The skirts are pretty rough on all of them though.

I'll get a micrometer over the weekend from a buddy of mine and measure them out. What dimensions are you looking for on the piston?


QT piston dimensions

OK ... great !!

Three measurements.

X Diameter of the wrist pin

X Distance between the top of the wrist pin hole and the top corner of the piston.

X Distance between the two 'ring locator' pins (in the ring grooves).

... just use a compass or divider (if you have one) and touch each pin with the tip .. then lay the compass on a scale and read the dim.

While we are at it .. confirm for me the QT's .. bore and stroke.

Re: QT piston dimensions

david f martin /

Bore and stroke (from the book):

40mm bore, 39.2mm stroke, 6:1 compression ratio. Piston clearance 0.035 - 0.047mm.


Re: Boredom Really Sucks.

Mope Head /

The problem with boredom is that it's so.........boring.

Or, as my nephew says, "Boringer and boringer."

Re: QT piston dimensions


Here are the specs:

Bore and stroke: 1.575" x 1.543" (standard)

Bore 2x: 1.594 to 1.595 depends on dia. of new piston

Wrist Pin: Length 1.297" +- .002 Width .394" +- .001

Wrist Pin hole (top) to top edge, not dome: .795"

Wrist Pin hole (bottom) to bottom of skirt: .695"

Piston Diameter 2x (tapered):

Top Dia. 1.583, Bottom Dia. 1.593

Clearance tolerances: .0014" min. to .0019" max

Hope this helps.


Re: QT piston dimensions

I ride a jin chieng knight a good bit.. It hink I even posted pictures of the one i ride in the forum several times if you doa search. They are 50cc 4 speed manual shift (foot)

so in alot of places that is what makes them not a moped.. also they do not have pedals.. they use either an electric or kick start... (they come with both)

The Knights do around 45 mph.. also making it not a moped. however in florida they are considered a moped and here in georgia they aren't..

anyhow.. they are fun to ride... they are more like a motorcycle.. almos the same size as those new honda 125.. I think rebels? I can't remember the name.. I think it is rebel.

Re: QT piston dimensions

Joe Hunt wrote:

> Bore and stroke: 1.575" x 1.543" (standard)

that Bore = 40mm .. same as a PA 50

> Wrist Pin: Diameter .394" +- .001

= 10mm .. same as a PA50

> Wrist Pin hole (top) to top edge, not dome: .795"

oooooooh! .. same as a PA50 !

Thanks Joe .. so a QT piston is almost the same as a PA50

Thats good .. because a QT being 'about the same' as a PW50 means pistons will be easy to find.

(I've had 2 dealers so far say they can't get oversized PA pistons)

If you are up to one more measurement .. (doesn't have to be precise .. a ruler will do) .. measure the spread between the two ring retaining pins in the ring grooves.

Re: QT piston dimensions


I just posted an URL with the owners manual specs. I don't know if they had that in there--- you'll get a kick out of the manual, the way it's written... the illustrations.

My wife got it online w/its own URL

the owners manual might come in handy for you someday. When I get to modding my QT's I'll rely on your knowledge of the similar model.

good luck


QT and PW

In case anybody was confused .. I did mean PW50.

(the QT being almost the same as a PW)

Because the PW50 is still being made .. which means its parts are easily available.

.. though technically .. I have HEARD the PW and QT are the same .. you never really know till you have the parts side by side .. or I find a PW owner with a piston he can measure.

...... anyway .. good to know

Re: QT and PW


Still need to measure that piston fer ya but seeing your latest post the PW and QT motor are interchangeable. Same mounts, cylinders, heads etc. My latest cylinder project was a PW with a QT piston and ring set. It was the stock bore and standard piston. I've got 130 lbs of compression and it rins like a top. I'm almost positive they are the same motor. The only thing that I would question would be the stator coil and electrics, but at first glance they look the same. I just bought a PW carb for a QT motor I'll let you know what I find out.

I do know that for the PW folks, to swap out the drive shaft and gear with a QT setup increases the top speed. Different gear ratio.

So it's a good bet that the pistons will work.

Re: QT and PW

Yeah .. I know they are 'basically' the same .. but it would be my luck to order $200 worth of parts from a 2002 PW for an 83 QT and find out that 02 was the year they changed them.

.. and on the gear ratio ... the QT gears give a lower gear ratio .. NOT higher !! .. the lower gear ratio helps kids on dirt racing PW's accelerate harder out of turns.

Racer dads have been making that gear swap for years.

... so it goes to say that I have often wondered what a PW's rear gear ring set would do for top end on a QT on the street.

(it might make the low end too slow .. but it might be 5 or 10mph faster on the top .. depending on what other motor mods might have been done)

Re: 'Sleeper' motors.

Or, possibly:

"Well son, state law defines a moped as a vehicle that will not go over 30 mph (or whatever it is in your state...) So it looks like this vehicle has been illegaly titled, registered, and tagged, let's take a trip down town..."

O.K. it's a little extreme and paranoid, but it could happen.

Re: QT and PW


I thought the street gears of the QT would be set up exactly the opposite to give the PW power out of the hole. Is it the tire/wheel size that makes the difference in the ratio? What size tires are they running on the PWs anyway?

What kind of parts are you looking for on the QT motor?


Re: QT and PW

Just curious, what are the SERIAL numbers on a PW case?


Re: QT and PW


Picked up 2 very clean 86 and 82 low mileage QT's today.


Re: QT and PW

Joe Hunt wrote:

> Picked up 2 very clean 86 and 82 low mileage QT's today.

.. lol ! .. whats the deal with QT's ? ... everybody seems to come across them in pairs .. (bought originally as his and hers I'm sure)

Don't have a clue about PW serial numbers.

Don't know why the gear ratio is that way ..

Makes sense as you say though ... wheels ... the PW's have 10" wheels as opposed to the QT's 16"s (??) .. so the smaller wheels needed taller gearing.

But the motor has to be un restricted to spin faster to make up for it.

I don't think I have any real interest in any other QT/PW parts .. mostly just the pistons since the Honda dealer told me my PA couldn't be had in oversize .. (he was real puzzled by that though .. doesn't make sense).

Though I am going to ask you one more 'measurement' question.

What is the spacing on the 4 cylinder head 'hold down' bolts ?

How much did the 2 QT's cost ?

Re: QT and PW

Don't know why I like them so much. They're super easy to work on. 90 pounds.They're great to ride, I ride mine to work when the weather is good. My wife will go to town center and get some groceries. I'll run a perimiter check (2o-3o minutes or so) 10 mile round trip. They're a great conversation starter.

The top speed on these will vary, but I can get them all to do 30 plus on the flats sitting up, faster if you lean forward. I have one scoot that I've over inflated the tires up to 36 psi. Hard as rocks but my top speed is 32-35 MPH. If you get them up to 30 there is another point where the RPM's will climb another 1000 or 1500 and you'll pick up 2 -3 mph. The motor is absolutely screaming.

Here's the measurement on the ring groove pins: 1.65"

Here's the measurements on the head bolts:

Center to center all 4 side are equal at 1.755"

the diagonal is 2.495"

Good luck on your project.


Re: QT and PW

Joe Hunt wrote:

> Here's the measurement on the ring groove pins: 1.65"

hmmm .. something is odd here .. the piston isn't even 1.65" diameter.

maybe we are talking two diff things ?

I was talking about the distance between the two pins ?

(on my PA they are 1 inch apart)

Re: QT and PW

My bad. It was a typo on my part it should have been 1.065"

Thats a straight shot across the piston side not accounting for the curvature.

sorry 'bout that


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