82 Honda Urban Express NU50 Rebuild

Helping a buddy of mine we came across his 82 Honda Urban Express NU50i. He rode it around Iowa City while attending college and it had basically been forgotten about. 2006 tag. Took it as "payment" and with my "FREE" noped I opened the can of worms and started "investing". Non running I cleaned the hell out of the carb and followed Freds guide. Got it running a stock 27 mph. Put the level 2 kit on and was running a zippy WOT 35 mph ALL DAY!, ALL DAY!

Removed the 3 worst looking weights for some small gains. Running 6 x 8 gram weights helped but I still need to swap 3 - 8 gram weights for 3 - 4 gram weights looking at 36 grams total (forgot my impact at work).

Replaced the BX31 for the Malossi and followed the wiki to convert the carb to accept Uni filter foam.

Installed the peoples side bleed pipe and my WOT acceleration took a massive dive but feathering the throttle I can accelerate and reach top speeds up into the 45+ mph range. Still need to GPS it but the pipe took top end to a whole nother level.

At this point I feel like my gearing is the only thing holding me back. I have the new clutch installed with the yellow contra spring but I feel like it's still not right. Might have gotten the wrong combo. Please advise me on my next step.

Parts installed:

honda urban express nu50 DR kit BIG BORE party - level 2

MLM honda urban express NU50 people's sidebleed pipe

OEM honda NU50 urban express battery

honda nu50 urban express tire n tube combo meal with a side of strips

treatland's SUPER HIGH QUALITY brake shoe PARTY - honda urban express nu50

dual stage reeds for honda NU50 URBAN EXPRESS by boyesen - MOD

gy6 50 scooter clutch - 107mm bell NU50 honda express clutch too !

honda SH 50 malossi special toothed belt

gy6 50 scooter REAR contra spring - YELLOW - 1500rpm

High Performance Racing Driving Wheel Roller 4 Gram Weight Set for GY6 50CC 139QMB 49cc 50cc Scooter Moped Jonway ATV

Uni BF-4 Bulk Fine Foam Filter (60 PPI) - 12in. x 16in.x 3/8in. - Black

Re: 82 Honda Urban Express NU50 Rebuild

Jack Rutherford /

Go for full power and then worry about gearing. You can get to 50+ with that set up. You can drop the weights to 27ish with that kit and pipe. Get a tach, determine the power band (rpm range ) where the pipe hits. On mine, it was 7500 to 9500 rpms. But different for different set ups. Determine your highest rpm and increase it if necessary. My top rpm was 10,410. Then change gearing. If after gearing, your max rpm is 8500 then you’ve lost half your power band. Gear down to keep most if not all of your power band.

Pretty much any change to the trans will affect gearing. You lowered gearing going from bx31 to malossi belt for example. (edited)

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