85 aero nb50m bbk questions. updates

[Kevinstonge]

Long story short I picked up an 85 nb50 and the piston is seized from an overheat. It's going to be for my girlfriend so I'm not trying to build a race scoot, but at the same time I always like to tinker and improve performance.. So my question is should I just replace everything with stock parts and just run it, or would it be worth it to go with a bbk(46mm is what I could find) and run the stock carb and exhaust at first, then maybe upgrade everything else later down the road??
Also does anyone know if different gear sets for the trans are avail for the aero?

One last thing i believe I read that the 85 nb50 has a different intake than the 86-87, and that there is no aftermarket intake made for the 85's yet... My question here is that is this a big enough issue that I should just keep the nb50 I have now stock, and search for another project... Thanks ahead of time guys and I'm glad to finally register on the forum after lurking for a long time now!

-Kevin

[Bear45-70]

It is true the 1985 Aero 50 intake is different. It is like the Spree and SB50, however tazland001 here on the forum has an adapter, intake and carb kit for the Spree and guess what, it bolts right onto the Aero 50 (NB50).

[Kevinstonge]

Thanks bear. I was a tually just reading that on a different thread I havnt read yet. Was I'm looking for is for it to do 42-45 and be able to pull right out into traffic. So far I'm thinking a keli vari with SEF ramp, 10:1 gears and a bbk for now.
Does anyone have any info or experience with the CMR, polini, or malossi bbk's for the nb50's?? Again thanks for any info given!!

-Kevin

[AeroVol]

Greetings Kevinstonge!

With your goals (42-45mph) i think you would be more than happy starting out with the bbk and some transmission work then moving on to the intake and exhaust. I am on a similar path and have already reached the 45ish+ range with the following setup.

Polini BBK
Ruckus variator with different weights
New drive belt (always a good idea while you're in there)
1000 clutch springs
1000 pulley spring (the big one inside the rear pulley)
stock airbox with 2 1.5 inch slits cut in it
stock carb rejet

This setup with my small frame ( 5'10" 140lbs) easily pulls wheelies from a stop and sometimes low speeds and achieves an acceptable top speed with brisk acceleration. My next step will be the fitment of a 20-22 mm carb with an aero 80 reed cage, dual stage reeds and a aero 125 intake. As for exhaust, thats still on the drawing board.

I hope my minimal experience with this powertrain can give you some direction and help with your choices. I really think there is a decent amount of potential in the AF05 engine for a fun street application.

best of luck,
AeroVol

[Kevinstonge]

aerovol, your information is indeed very helpful and appreciate the response. i will definitely be going with a similar setup. i have a polini bbk on the way. once the engine is broken in i will then move on the the ruck variator, and hopefully a set of 8.3:1 or 10:1 gears. i am also very eager to start playing around with the af05 engine as its a classic yet very tunable!

[z50r-ghost]

Just an idea... I have a NEW 1985 Honda aero 50 (nb50) OEM crank and bearings if you need it for your build. It cost BIG moneys from Honda!

I would sell it cheap!! Good luck with your build!

Lmk, later j

[maddog]

yes i know all about the nb50 engine as in 1987 i built the fastest one with the parts that were available at the time, 3 engines later, the first one was sold to a michigan drag strip, the 82cc fabrezzi which i still have will go into the shop owners window , and the rare 108cc full stroker along with every known japan option= cool

[Kevinstonge]

ghost- im hoping the crank assembly and bearings are still in great condition. ill be opening it up soon, so if thats not the case then i guarantee ill be sending you a pm!!

maddag- your an animal. 108cc is a massive build. i would love any advice you have to give on the nb50..

and also ive been thinking about the engine break-in period. ive read a couple differnt opinions on the subject. as of now i think i will keep it under 30mph/1/4-1/2 throttle for 150 miles, then 35-40mph/1/4-1/2 throttle for another 250 miles. after that im unsure if i should do something else... any info/opinions are welcomed and appreciated! oh and besides the bbk and 90/90-10's, it is stock.

[bradthreee]

Share some pics Maddog

[Bear45-70]

Share some pics Maddog

That will be the day.

[Wheelman-111]

Greetings:

Gearing the SE/05 to your Polini 65cc will be a challenge. 10:1 gears are still pretty short, although they might permit speeds of up to 45 or so. 8.3s are decidedly too tall to "shoot out in front of traffic..." unless you really kit out that BBK including a substantially bigger carb. I submit your best bet might be to hit up TrafficJams for a primer in conversion to SA/16 gear train, then install 9:1s on the SA axle.

[Kevinstonge]

conversion to SA/16 gear train, then install 9:1s on the SA axle.

That's the plan. I did more research and read that the 9.1's with a bbk can over rev in long downhill applications. But I figure I'll just be careful because it will be worth the extra acceleration over the 8.3's. Plus I was looking into a ruckus variator down the road which I believe will stretch the legs just a touch as well.

What I'd like to know more about is the actual af16 gears the the 05 gearcase. Can I just replace my primaries and final shaft with stock af16, and secondaries with aftermarket dio gears..?? I found a set of 9.1:1 secondary gears on eBay. And on Honda fiche I've found the primaries for like 60ish for both gears.. Only I can't find the final shaft( axle that the larger secondary gear is pressed to) anywhere.... And Please correct me if I'm wrong or mistaken about any of the above...

[bradthreee]

What kind of RPM's can the stock crank handle?

[Kevinstonge]

well the nb50m has been on the back burner for a while but im trying to plan ahead for the spring(scooting weather).
I got the polini bbk installed and although it needs more break in time, its running great.
A couple new questions i have are to do with the intake side of the af05. right before i stored it for the winter i noticed a decent exhaust leak in the muffler so i have an sp3 on the way. with that being said i also installed a 270mm shock to clear it, but its leaving me with the obvious air filter clearance issue.
some known plans for my aero are
ruckus vari
9.1 gearing
sp3 pipe
premix
so the question is should i just stick with the stock intake/carb and use a pod filter? should i contact taz about the spree adaptor and setup?
my main goal is to try and keep it as simple as possible while attaining the speeds that i'd like(50-55 gps)

also i have tried searching but couldnt find the exact answer i'm looking for. I AM aware that these questions are slightly noobish but that's because im a noob and unfortunately cant give my beloved nb50m as much attention as i'd like with my other projects i've got going on.( vw's, toyota pick-ups, 4-stroke hondas)

thanks ahead of time and any info/advice is Always appreciated.

[Mystic]

89eliteR just build something similar to yours, he modified the stock reedcage by taking the reeds out and cutting out the center to use as an adapter for the ct mani. maybe this will work for you instead of trying to hunt down a special made adaptor unless your aero has the 2 bolt cage versus the 4 bolt like dude has.