Honda Motocompo NCZ50 - The build log!

Hello guys,

Thought I would formally introduce myself from way over the other side of the world in Australia. I’ve actually been pouring through this wonderful site for some weeks as there is a whole host of really useful information on NC50/NU50/PA50’s which is somewhat applicable to my bike below.

I imported this myself from Japan, about a year ago now. For some it will be instantly recognisable, but for those not in the know it’s a Honda Motocompo (NCZ50). Specs are a single speed, air cooled 49cc 2 stroke rocket ship! This is of course a fold up ‘trunk bike’, which was designed to fit in the back of a Honda City.

My contact is Japan was able to contact Honda Japan and determine it rolled off the production line on March 10 1982. It was received in quite nice condition. A few bumps and bruises from her 35 years, but nothing too terrible by any means. A nice straight un-rusted frame. And for better or worse (probably better actually), it had sat forever so every jet in the carb was fossilised, but after a good clean she ran first time.

I will attempt to make this thread into a rolling record of updates, as like most, I would love a little more speed. To that end, I tested her in unmodified form and managed a top speed of 38km/h on the GPS, or close on 24mph for you non-metric folk. Not bad for running on an 8” tyre I reckon!

Test Run - 38kmh

It was at this stage I decided it wasn’t perhaps the most sensible idea to run this unregistered, so went through the process of applying for road legality, which it now is.

For the next post, - the Expansion Chamber!

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Re: Honda Motocompo NCZ50 - The build log!

Part Deux

So after deciding that it’s not safe to play with cars that are capable of rolling over me even at my 24mph top speed, I decided it was time to get serious with some power improvements. Well actually, in truth, I just have a bad habit of ploughing money into modifying cars, and even though it’s only 2.5hp, the Motocompo hasn’t escaped the same attention!

There is a fella in Japan that hand builds expansion chambers for these critters, which are claimed to yield a 6mph improvement. The only downside was the cost, which at USD$300+ makes them a little bit pricey. All the more so when it arrives on your desk at work and you discover it’s barely larger than your keyboard! So after a few weeks of procrastination, I found some time to fit the pipe, and made the effort to wrap it in exhaust header, since even the standard mufflers are known to get hot enough to melt the plastic fairings.

Now, with no other changes to the bike I was able to pick up 8km/h (5mph) on the top end to increase to 46km/h / 28.5mph. It is worth noting that my tyres were definitely a little flat due to sporadic use, and so I think I could have hit 30mph had the tyres been properly inflated. I have since pumped them, and so will do one more run to confirm top speed before moving onto the next phase of the project.

For the next post I’ll also include some pics of the Vapour Trail Tech that I installed to keep an eye on all systems, plus update on my 70cc plans!

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Re: Honda Motocompo NCZ50 - The build log!

Great bike, I"m looking forward to this thread. What are you plans? Mostly stock? All out? Also, I like that green tool chest / work bench / desk, it reminds me of a Vidmar bench I had at work, or maybe a Lista brand. Motocompo turns heads all over, even down under!

Re: Honda Motocompo NCZ50 - The build log!

Cheers for the love.

Outwardly I want it to appear pretty much stock, except for the hint of the expansion pipe, and the Trail Tech on the nose. I'm certainly not planning on any of the craziness that the Japs do with extended swing arms and monstrous tyres etc! However, I still want it to go like a scalded cat :)

I'd love to hit 40mph and call it a day. I bought a bunch of stuff from Treats a while ago, including the Polini 70cc kit, and Malossi intake manifold with Dellorto 21 PHBG carb. I'm actually building that on a 2nd chassis I acquired, which will be switched across once the time comes. (edited)

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Re: Honda Motocompo NCZ50 - The build log!

So cool! That pipe is a thing of beauty! 40 mph on one of those would be scary...but in today's traffic prob needed, watch for potholes..they could end both you and the bike too at that speed. Keep us posted!

Re: Honda Motocompo NCZ50 - The build log!

Yeah on the 8" tyres it's more like driving through a pothole rather than over it! I'm not planning to get on full throttle everywhere, but just to have that extra speed in the back pocket would be nice to have.

Re: Honda Motocompo NCZ50 - The build log!

Wheelie videos please.

Re: Honda Motocompo NCZ50 - The build log!

Us non metric folks also say tire rather than tyre. Cool beans on the bike!

Re: Honda Motocompo NCZ50 - The build log!

Paul Boyer (OFMC) /

Very cool!!! Love following this build.

Re: Honda Motocompo NCZ50 - The build log!

WOAH SICK!

thanks for posting, i won't even bother with the WFFF because in US its technically a scooter.

is it an 'express' powertrain? Variated? single speed?

Re: Honda Motocompo NCZ50 - The build log!

Yeah more info on parts crossover between Honda models too plz. Love this thread!

Re: Honda Motocompo NCZ50 - The build log!

Commenting to follow this thread. This shit is already rad as hell.

Re: Honda Motocompo NCZ50 - The build log!

when you put the new carb on you should change the reeds to carbon since the old ones might be metal. Maybe take a pic of the reed block since there are like 5 different ones depending on what honda model it is also some flow better than others PAI vs PAII and some of the express reed block for example.

Also that pipe looks awesome and pretty well made.

Re: Honda Motocompo NCZ50 - The build log!

Dan (LandLordsMG/PSVMC) /

hell yes, make it happen capn

Re: Honda Motocompo NCZ50 - The build log!

That's super cool!

Re: Honda Motocompo NCZ50 - The build log!

Into it

Re: Honda Motocompo NCZ50 - The build log!

Probably Fred /

Toby B Wrote:

-------------------------------------------------------

> Part Deux

>

> So after deciding that it’s not safe to play

> with cars that are capable of rolling over me even

> at my 24mph top speed, I decided it was time to

> get serious with some power improvements. Well

> actually, in truth, I just have a bad habit of

> ploughing money into modifying cars, and even

> though it’s only 2.5hp, the Motocompo hasn’t

> escaped the same attention!

>

> There is a fella in Japan that hand builds

> expansion chambers for these critters, which are

> claimed to yield a 6mph improvement. The only

> downside was the cost, which at USD$300+ makes

> them a little bit pricey. All the more so when it

> arrives on your desk at work and you discover

> it’s barely larger than your keyboard! So after

> a few weeks of procrastination, I found some time

> to fit the pipe, and made the effort to wrap it in

> exhaust header, since even the standard mufflers

> are known to get hot enough to melt the plastic

> fairings.

>

> Now, with no other changes to the bike I was able

> to pick up 8km/h (5mph) on the top end to increase

> to 46km/h / 28.5mph. It is worth noting that my

> tyres were definitely a little flat due to

> sporadic use, and so I think I could have hit

> 30mph had the tyres been properly inflated. I have

> since pumped them, and so will do one more run to

> confirm top speed before moving onto the next

> phase of the project.

>

> For the next post I’ll also include some pics of

> the Vapour Trail Tech that I installed to keep an

> eye on all systems, plus update on my 70cc plans!

>

>

Did you Upjet/make jetting changes when you put on the performance pipe? seems like you should've got a lot more performance, are you running a performance mesh filter ? If you change the exhaust output you got to change the input of the carburetor/air filter to match.

I suggest you get a head temperature gauge to aid in tuning and to keep you from locking your engine up as well as finding a way to gear higher for more top speed

Re: Honda Motocompo NCZ50 - The build log!

Thanks for all the appreciation guys. I'll update in proper over the next couple of days as I recover from the flu. In the mean time, a snap from Saturday's run. That equals exactly 30.07mph!

Will chime back in soon.

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Re: Honda Motocompo NCZ50 - The build log!

that pipe is fucking awesome

Re: Honda Motocompo NCZ50 - The build log!

Tobias Doesn't Care (ง •̀_•́)ง /

Posting to follow this thread. This is exactly what I want to see happen to a motocompo

Re: Honda Motocompo NCZ50 - The build log!

@ Graham Motzing, Have to confess I needed to search for the meaning of WFFF, but hopefully you'll cut me a little slack on account of the heart of the beast being so closely related to its Hobbit / Camino brothers! Besides, - I wouldn't be caught dead on a scooter forum. Isn't that all about skinny jeans and debates between macchiato and piccolo's? :)

@ will warn, i'll comment on the reeds in my next post, which I specifically made a point of taking photos of for you.

@ Ken Roff, the standard carburetor on these things is a piddly 13mm Keihin which has a press-fit main jet which can't be removed. The best you can hope to do is drill a hole through it to replicate up-jetting, although since I plan to ditch it for a Dellorto, I don't plan to butcher the oem carby, incase I ever want to go back to standard config.

I am however surprised that you feel going from 24mph to 30mph (25% bump) is not as much as you'd imagine. What do other mopeds typically see with just a change of pipe? (edited)

Re: Honda Motocompo NCZ50 - The build log!

Ken's a good dude but he's not gonna be happy until you're using a performance mesh filter

Re: Honda Motocompo NCZ50 - The build log!

So the update as promised!

The goal for last weekend was to complete the install of the speedo sensor for the Vapor, pump the tyres up, then go for another hit to verify top speed.

But firstly, - the Vapor. I was originally going to buy the most basic model which measures just the cylinder head temperature. But given the 70cc upgrade was always in the works, I thought it might be useful to also monitor RPM’s and have a Speedo once the new engine was in. Setting up the RPM and temp gauge was easy enough, but I had to figure a way to make a bracket to mount the speedo sensor, which I have placed on the rear wheel. Apologies for grainy photos in my dimly lit shed, but you get the idea. That being done, I calibrated it by sitting my weight on the bike, rolling forward 4 full rotations, and divided by 4 to get the tyre circumference, which was programmed into the Vapor.

As per the photo in my last post, it read a top speed of 48.4km/h, or 30.07mph, which is exactly what I expected with inflated tyres. For whatever reason, the GPS app I was using on my phone registered 58km/h (36mph), which from this point I am going to disregard as I believe I have the calibration of the Vapor dialled in to within 1mm of the actual rolling circumference. As a side note, the max head temp was 405F.

TBC...

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Re: Honda Motocompo NCZ50 - The build log!

...

Part two of the experiment was to be a back-to-back test under the same conditions, but with the dual stage Boyesen fibreglass reeds. As you can see from the pics, it seems the flaps open first under low revs, with the big windows opening up under higher revs. After blipping the throttle, the response is noticeably more crisp. With hopes high, I rode back to the same spot that I managed my 30mph run, but then had the misfortune of overestimating how much fuel I had on board, so ended up pushing it back 2 miles to the nearest gas station. And that is where the experiment ended.

On the upside, my 70cc assembly is close to being ready, so I was not going to delve any further with this setup, however, Ken has piqued my interest in what that pipe might be able to achieve with proper jetting, so I am now contemplating an intermediate stage of attempting to tune the Dellorto to the 50cc setup first, to quantify the difference it makes. Once the 70cc is ready, it would then also give me an idea of whether the overall improvement is coming from the extra capacity, or the better carburetion.

So in summary, the planned evolution will probably be: Factory 50cc (24mph) --> 50cc + Pipe (30mph) --> 50cc + Pipe + Reeds (top speed TBA) --> 50cc + Pipe + Reeds + Dellorto --> 70cc + Pipe + Reeds + Dellorto.

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Re: Honda Motocompo NCZ50 - The build log!

This is a cool thread.

Re: Honda Motocompo NCZ50 - The build log!

"back-to-back test under the same conditions"

we need to do this more

Re: Honda Motocompo NCZ50 - The build log!

17% off at Treats this week!... might get a couple more Boyesen reeds to experiment with and probably a Puch head to get a little more cooling on the forthcoming 70cc setup.

Re: Honda Motocompo NCZ50 - The build log!

Graham Motzing Wrote:

-------------------------------------------------------

> WOAH SICK!

>

> thanks for posting, i won't even bother with the

> WFFF because in US its technically a scooter.

>

> is it an 'express' powertrain? Variated? single

> speed?

Specs as per your request!

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Re: Honda Motocompo NCZ50 - The build log!

@ Graham Motzing, I just ordered a 46mm Puch Airsal head, which will need to have the holes slotted to suit the Honda stud pattern. To that end, I have been attempting to bring myself up to speed on the best way to achieve this and have read a couple of references to a bushing kit that you are repeatedly credited with. I don't suppose you'd be able to point me in the right direction as to how I might lay my hands on one?

Re: Honda Motocompo NCZ50 - The build log!

It occurs to me that I haven't posted any pics of the Motocompo with the vehicle that is tasked with carrying it, - my Honda City Turbo II. It's a last of the line model built in 1985, in which Honda finally ditched the questionable all blue interior and went with a more subdued black. Together, they're an awesome pairing.

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