Re: Honda Motocompo NCZ50 - The build log!

> Toby B Wrote:

> -------------------------------------------------------

> Will, to clarify, i will be slotting the holes in the monster Puch head,

> to fit the Honda stud pattern.

Oh yea I had a different idea all together, I was way off.

Re: Honda Motocompo NCZ50 - The build log!

I'm no spark plug wizzard, but ive always used colder (6/7) spark plugs and not 5. So that could be it, but read up for yourself wiki and maybe someone with more knowledge can chip in.

Re: Honda Motocompo NCZ50 - The build log!

Even though you're confident you don't have any I would still check for airleaks.

Re: Honda Motocompo NCZ50 - The build log!

The wiki dellorto tuning guide is a pretty good resource if you haven't read up on it already

Re: Honda Motocompo NCZ50 - The build log!

Yes i've read the dellorto tuning guide so many times I could almost recite it!

Re: Honda Motocompo NCZ50 - The build log!

In that case I'm thinking you've already outlined the most obvious next steps...

1. Colder plug

2. Install new head for better cooling

3. Check for air leaks after new head (i find that starter fluid is more accurate than carb cleaner when spraying for leaks)

4. Adjust main jet/needle accordingly. I know dellorto also has several needle tapers and throttle slide cutaway options, so dialing in WOT first and working backwards is probs easiest

5. I'm not sure how much airflow can get to the cylinder under those plastics, maybe you can mock up some temporary fairings with cardboard to direct more airflow and get better cooling?

Re: Honda Motocompo NCZ50 - The build log!

agreed on a colder heat range.

the one thing you've not thrown on the table is the stock CDI unit.

changing the base timing and the curve with a different controller may be a better direction.

you've put the motor into areas the stock CDI isn't designed for.

i bet it's just adequate

issue is, your location won't allow for easy trial and error.

> Toby B Wrote:

> I welcome any and all input!

Re: Honda Motocompo NCZ50 - The build log!

Hepatitis J [OFMC] /


Re: Honda Motocompo NCZ50 - The build log!

OMG I can't believe you have the car to go with the bike. You're my hero. I've been wanting a Motocompo for so long but haven't had the spare change to make it happen. Some day.

Re: Honda Motocompo NCZ50 - The build log!

annnnnnnd I officially hate you. Green with envy.

Re: Honda Motocompo NCZ50 - The build log!

todd amundson /

Saw these last night at a party here in LA. They are all owned by one guy apparently.


Re: Honda Motocompo NCZ50 - The build log!

make sure you're timed accurately and then retard your timing a little.

Re: Honda Motocompo NCZ50 - The build log!

Gigantor puch head slotted to fit Honda bolt pattern and ready to go on.


Re: Honda Motocompo NCZ50 - The build log!

Great work! I have the same mop needs some tuning too. I am thinking of replacing the stock rectifier with a more modern one and all lights to LED goodness. But I don't have a users manual. Is it possible share your manuals wiring diagram. Thanks a ton!


Re: Honda Motocompo NCZ50 - The build log!

PM me with your email details and we can sort something out.

Re: Honda Motocompo NCZ50 - The build log!

Some experimentation with the big Puch head. Does help to keep temps down a few extra degrees, but the largest difference in heat output was achieved when I filed out the two stator mounting holes, and rotated clockwise a couple of millimeters to retard the timing a little.

Unfortunately it's still experiencing some sort of rev limiting affect, as whenever I get super close to 5,000rpms, it falls on its face. There is a post in the comments section of this article ( that pretty much describes my experience to a tee;

Hi, I'm new to the noped community, I bought a 1982 Honda Urban Express to ride back and forth to work and turns out I really like this little bike. It's in fairly good condition, but needs a good cleaning. I'm not very mechanically inclined but am learning all the parts, etc. I was reading your comment on a governer or rev limiter and how there is none, but I could swear that my express has one on it. I get up tp about 32 or 33 mph (it happens at the same speed every time) and you feel the engine stop accelerating, it just kinda cuts off, and you hear the rpms wind down and once it drops to a slower speed, like 30 or 31 mph it comes back on and accelerates just to cut out again at the same speed. Is this a govener/rev limiter?? (is there even a difference?) If so, how do I disable it? and if not, then what is it? Thanks so much for the help, I really like this website, there are a lot of interesting things on here and it will be a big help as I start to work on my express.

Still thinking that it may be some witchcraft within the factory CDI, i've gone ahead an ordered a Yamaha Jog 50 CDI and an A3202, since you Hobbit guys seem to be fairly split on what the best option is.


Re: Honda Motocompo NCZ50 - The build log!

Have had same rev limit type symptoms on my nu50 for years, hope u can help! Great thread homz!


Re: Honda Motocompo NCZ50 - The build log!

I stock motocompo revs above 7000rpm with no problem. But it tops out at about only 25mph. Just wonder, how did you achieve 30+mph with only 5000rpm?

I just made a noobie mistake and blew up my new piston yesterday. I took it for a ride after top end rebuild for a about 30miles and all of sudden I heard some clicking noise and engine then seized.

Maybe it was running too lean since I used the factory carb setting with a high air flow pod. But the plug was burnt nicely to my noobie eyes, it was dark brownish colour.

Re: Honda Motocompo NCZ50 - The build log!

Hi Cooper,

Originally I thought it was running at 10,000rpms, according to my trail tech. However, I think I might have the setup wrong, as I thought i read somewhere that max revs on the motocompo was 5,000, so figured i needed to divide my setting by 2. However, thinking about it now, it's quite possible that 10k is correct, and that factory maximum power on the motocompo is achieved at 5,000rpm, but is not necessarily the rev limit.

Anyway, 30mph was achieved with factory setup with expansion pipe.

I had a A3202 CDI arrive this week, so in a little while i'll play with that and see if i'm still rev limited.

Re: Honda Motocompo NCZ50 - The build log!

Hmm, I am using an inductive tachometer and used the idle speed as my reference rpm for setup. I know the spec for the idling Rev is around 1800rpm. And the clutch will start to engage at this rpm as well. dividing or multiplying 1800 by 2 will give me impossible idle rpm.

The max rpm I have seen on my bike was around 8500rpm. Btw, what tachometer are you using? I can see from your pics that you are also using a inductive type, picking up signal from the plug wire. It can be very prone to interference from the other wires, such as the lightings and signaling. It can give you false readings if you run the tachometer sense wire too close to them.

Re: Honda Motocompo NCZ50 - The build log!

Mines a Trail Tech Vapor. And yes, picks up on the pulses from the ignition lead. It's definitely revving to close on 10k. I was also running a dual stage Boyesen reed which absolutely makes the top end a whole lot less fluffy. Coupled with the Natty Works expansion pipe, it'll get you closer to 10k.

Re: Honda Motocompo NCZ50 - The build log!

Go back to page 1. I clocked 30.07mph @ 9400rpm.

Re: Honda Motocompo NCZ50 - The build log!

> Mike Boyd Wrote:

> -------------------------------------------------------

> holy shit you have the car too. i love this


Re: Honda Motocompo NCZ50 - The build log!

OK, so another update.

I’ve continued struggling for revs and power with the Puch head, so after translating the work of some trailblazers in Japan with these bikes, I went back and gave the factory head a shot. Then viola, - back past 10k rpm again with a bit more speed. It then became clear that all I needed was some more compression.

However, I was surprised that the custom 46mm cut NU50 head (like this one:, would affect compression so much. It wasn’t until I decided to fill all three heads with liquid did I realise the difference in volume. From left to right, oem head -> custom 46mm cut NU50 head -> 46mm Puch head.


The oem head came in at 7.5ml, and the other two were around 10ml. The real question for me was how the custom NU50 head gained so much volume when the only expected change was machining the outer rim to 46mm. Well… it looks like the reason owes to the bowl being machined too! For whatever reason, the bowl section has a lot less meat than the factory head.


As standard (49cc), I calculate that the CR would have been something like 6.5:1.

Once I went to 70cc and the bigger heads, CR would have gone to something like 7:1, but for whatever reason still ran shit up top.

With the current oem head paired with the 70cc kit, CR is probably 9.3:1 ! Maybe that’s why the bowl is machined out of the NU50 custom cut head, - to keep something similar to a factory compression ratio?

Either way, for the moment I will continue to run the oem head, until such time that I can machine down the Puch head to give the double benefit of extra cooling and more compression.

Part 2 of my experiments to follow next…

Re: Honda Motocompo NCZ50 - The build log!

Less time in between updates please, lol

Re: Honda Motocompo NCZ50 - The build log!

Next chapter…

When I was struggling with rev and temperature issues, I started playing with the stator plate. I filed out the mounting holes a little bit and rotated to retard the timing an extra couple of degrees. I actually had good success with this, but wanted to try some different CDI’s to try and find one with a curve. The two I ordered were the A3202, and the Yamaha Jog box, since they are the two most mentioned in the Hobbit community.

First up the A3202 which arrived first. Wired it up, and it started first kick. Though it would not idle properly and bogged and died when so much as breathing on the throttle. Strike this one off the list.

Next up, with hopes low, was the Yamaha Jog box. Wired her in, kicked over straight away. Idled nice and steady so took it for a run. The biggest plus here was the operating temperature which was a good 20-30deg Celsius cooler (down from ~440F peak to about 390F). Only downside was less peak revs and a couple mph less top speed. On the factory CDI I was running about 57km/h (35mph) at over 11,000rpm. The Jog CDI was about 54km/h (33mph) at a bit past 10,000rpm. I am going to test both CDI’s back to back again, just to confirm.

I’ll also be chucking the modded reed valve back in, to see if there is any difference.


Re: Honda Motocompo NCZ50 - The build log!

Have mine mildly bored up, good compression out of the box; should get better as I break it in. It was about 100psi, now it is 130psi.

Since the kit didn't come with a new wrist pin needle bearing, I had to stuck with the stock one. But I realise there's ton of side to side play between rod and the piston since the new piston is 43mm. Is it normal? I dont want the bearing to blow up again in my cylinder..


Re: Honda Motocompo NCZ50 - The build log!

To fill the time, some pictures of another one i've just finished restoring. Yellow is my favourite of the three options. Will actually be up for sale in the next week or two.


Re: Honda Motocompo NCZ50 - The build log!

Brandon Weiss (Detective brandon to you) / much? Wish i had money for that

Re: Honda Motocompo NCZ50 - The build log!

It'll be a few grand USD i'd say, going by market price in Australia.

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