81 NC50 big bore kit

81 Honda NC50 big bore

I’m looking at getting a big bore kit for my stock (for now) 81 NC50.

Treatland has a kit big bore kit

That looks great. Will this work with no machining to the case and can I use the stock head?

My old piston/cylinder are junk not wroth using.

Thank You for looking

Re: 81 NC50 big bore kit


Re: 81 NC50 big bore kit

What was the question???

You might need to do a search to find your answer.

Re: 81 NC50 big bore kit

normally these will fit right in, however make sure you check the head clearance . check the jetting and a pipe of some kind will go a long way. the DR is a nice kit so is the malossi and polini for people who run cast iron i would look around for pricing though

Re: 81 NC50 big bore kit

Make sure you have clearance to get to the oil fill for the trans, most kits need a little fin trimming.

Re: 81 NC50 big bore kit

yes some fins will need to be cut back but the cylinder will work and slide on.

Re: 81 NC50 big bore kit

Thank you all very much. It's the small things I like to be prepared for.

Re: 81 NC50 big bore kit

I suggest you practice getting it tuned perfectly with the stock set up before attempting a kit you will stand less of a chance of having a failure or destroying your new kit it that way check the wiki and download the manual to it will assist you

Re: 81 NC50 big bore kit

I have used a DR kit on a NC50, you can use your stock head and it fits right in the case and maybe a nip off two fins if they hit the foot peg support on the drivers side only. You will need to up size the carburetor jet.

The Malossi 70cc kit recommends this jet or drill bit (comes with kit)

But the DR kit is the most trouble free of them all. Someday if you are still into mopeds and need another kit I highly suggest the Parmakit (70cc).

The Malossi jet wont work in the stock carb.



Re: 81 NC50 big bore kit

> bob john Wrote:

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

> you can use your stock head and it fits


This is half true^


Cooling is going to be an issue. I have metal scoop that rams air around the head and cylinder that seems to help. A head temp gauge is cheap insurance too.

Re: 81 NC50 big bore kit

^^ This makes me think... The express I started with had been tampered with before me. So its possible the head I had was already cut for a big bore.

Re: 81 NC50 big bore kit

Could be possible. Pull the head and check to be sure.

Most big bore kits have the decomp passage, so that has to be blocked if you are running the express head. Cutting the head could fit in a bigger cylinder, but it's the decomp air leak that would be a problem. So check that.

Express heads are even smaller than hobbit heads, which are notorious for not dissipating heat, but they are better than stock. They can be found precut for kits.

Check out the wiki for more information.


Also this it a pretty helpful site.


Re: 81 NC50 big bore kit

Now I'm looking for a better head. Looking around I've seen that the head gasket for the hobbit is the same as the Camino, PA50, PA50II, NA50, NU50, NC50. Anyways will this also fit a NC50 Puch Airsal 46mm Head or Honda Hobbit headBoth have no hole for the no decompression.

Cooling looks to be a big need.

Re: 81 NC50 big bore kit

The Puch hole pattern is off by 2mm but will work if you can side drill the holes. I got a drill bit from Harbor freight. I am no expert and dont know if there are many different puch heads, maybe I got lucky?

I just looked at Treatland and they have a cut 46mm Hobbit head with some chipped fins for $55 12/19/2017. The Hobbit head will work without a doubt.



Re: 81 NC50 big bore kit

About 18 posts down there is a Puch on Hobbit article(4:00am) 12/19/17

Re: 81 NC50 big bore kit

Got done reading the article........Puch 47mm euro kit......Is what you want to buy.

Re: 81 NC50 big bore kit

I was looking at that thread and well done capturedbyrobots but that's not my style. A millimeter or so trim is what I'm looking to do. The hobbit head looks good so far. Thank You much for the help

Re: 81 NC50 big bore kit

That's a total waste of the effort to modify a head and still end up with crappy Hobbit cooling.

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