81 Honda Express SR

pureliquidhw · 06-07-2010, 08:58 AM

My buddy just gave me his NX50 that he had sitting under a pine tree. After removing the sap and cleaning the carb, she runs!

Still having problems tho and another friend of mine pointed me here.

She idles fine when the rear brake is engaged (and thus the clutch disengaged?) but when i let go of the brake, it just opens wide and tops out @ 20mph.

The CVT transmission doesn't seem to be moving at all either, but i can't be sure since there is no response from the throttle even after tweaking it.

Anywho, seems like i have some work cut out for me but you can't beat free!

wanna bECO · 06-07-2010, 05:10 PM

Quote:

Originally Posted by pureliquidhw

. After removing the sap and cleaning the carb, she runs!

This is a common problem on old hondas... sap in the carb!

what a deal.. I love it. Have you ever heard of any other bike that comes up fromt he dead better than these old honda's?

pureliquidhw · 06-08-2010, 08:23 AM

totally. in my infinite wisdom i put the throttle body on backwards and it was stuck half open. Now the throttle works fine, but the engine not so much.

The scooter does fine under light throttle loads, but when I rip on it if bogs down. I re-gapped the plug but that didn't fix it.

Then, once warm. The engine just quits. I don't know if it was just flooded or if there is some kind of compression issue (please god no).

This morning I was told the gas is over 2 years old. I'm surprised it ran at all! I'm going to drain the tank and get a fresh batch of 92 octane petrol as well as some smokeless 2 stroke oil.

So basically I'm attacking from all angles. And since it was so hard to find any info on the NX50 i might just post a cleaner version of my trials up top.

ADV scoot · 06-16-2010, 08:38 AM

I have a 77 express that I am having the same problem on. My grandmother gave it to me and it had been sitting in her garage for 25 years.
I gave it to a guy that has worked on old Honda's for 50 years.

He says that the crank seals are bad and the oil from the trans is leaking threw.
witch makes it idle ok, but when you get on the throttle it will bog down.

He is still having trouble with it. I hope to get it back soon.

YamaGeek · 06-16-2010, 11:02 AM

One thing common to the old Express was a problem with the oil injection pump with age either pumping through too much oil or not enough. The common fix is to disconnect it and run 30:1 premix. Mine had the too much oil problem with it fogging the neighborhood and attracting the attention of the local LEO's.

I'd also take the carb completely apart and clean it thoroughly the main jet seems to get plugged easily and the float valve can get munged up also.

I don't understand how you got the carb put on backwards the mount flanges from the intake/reed manifold are entirely different from the air filter body.

pureliquidhw · 06-17-2010, 10:05 AM

I put the throttle cylinder thing in backwards. The carb was on right lol.

I finally got new gas in it, but that didn't help. I am running premix, approx 30:1 like you said.

I cleaned the carb following the instructions posted online, and tested the float, compression, throttle adjustment, Idle screws were set to OEM recommendations, but all I could get it to do was a crappy idle at full throttle. It looks like the carb is overfilling with gas and it is running too rich.

I finally gave it up to a local scooter shop. He quoted me $35 bucks to get her running well (since i already had it running). I'm good with that considering I would be dropping that much on parts that I probably don't need.

Thanks for the comments!

YamaGeek · 06-18-2010, 07:24 PM

You might have the shop richen the jetting a smidge. The premix oil will lean the mixture a bit.. One of the easiest quick fixes was the run a really long 5/16" drill bit down the muffler opening, it will open the exhaust some and let it breathe better.

Zombie_Stomp · 07-18-2010, 07:19 PM

how about the one with auto choke. Any tips for converting it to manual choke, or what to do about the failing auto choke?

romans racing · 07-18-2010, 09:06 PM

Go to www.mopedarmy.com , check piston rings and exhaust for carbon buildup, needs to be cleaned about every 1000 miles for a good running bike, and clean carb pilot and main jets with a micro drill bit, or wire.

slime · 07-25-2010, 08:42 PM

Quote:

Originally Posted by Zombie_Stomp

how about the one with auto choke. Any tips for converting it to manual choke, or what to do about the failing auto choke?

I have an '82 Express 2 that has that crappy auto choke. I was told it's the same carb they used on the Jazzy? Mine likes to die going off idle to throttle. I know the carb needs cleaned and or replaced!

06-07-2010, 08:58 AM	#1
pureliquidhw ^OP n00b Joined: Jun 2010 Location: WI Oddometer: 3	81 Honda Express SR My buddy just gave me his NX50 that he had sitting under a pine tree. After removing the sap and cleaning the carb, she runs! Still having problems tho and another friend of mine pointed me here. She idles fine when the rear brake is engaged (and thus the clutch disengaged?) but when i let go of the brake, it just opens wide and tops out @ 20mph. The CVT transmission doesn't seem to be moving at all either, but i can't be sure since there is no response from the throttle even after tweaking it. Anywho, seems like i have some work cut out for me but you can't beat free!

06-16-2010, 11:02 AM	#5
YamaGeek Ancient trailbike padwan Joined: Jun 2007 Location: western oregon Oddometer: 4,154	One thing common to the old Express was a problem with the oil injection pump with age either pumping through too much oil or not enough. The common fix is to disconnect it and run 30:1 premix. Mine had the too much oil problem with it fogging the neighborhood and attracting the attention of the local LEO's. I'd also take the carb completely apart and clean it thoroughly the main jet seems to get plugged easily and the float valve can get munged up also. I don't understand how you got the carb put on backwards the mount flanges from the intake/reed manifold are entirely different from the air filter body. __________________ ____________________________________________ We're here because of a love most exestential. (toothy)

06-18-2010, 07:24 PM	#7
YamaGeek Ancient trailbike padwan Joined: Jun 2007 Location: western oregon Oddometer: 4,154	You might have the shop richen the jetting a smidge. The premix oil will lean the mixture a bit.. One of the easiest quick fixes was the run a really long 5/16" drill bit down the muffler opening, it will open the exhaust some and let it breathe better. __________________ ____________________________________________ We're here because of a love most exestential. (toothy)

07-18-2010, 07:19 PM	#8
Zombie_Stomp Aspiring human Joined: Jun 2007 Location: SE Portland/ Carrboroland NC Oddometer: 2,180	how about the one with auto choke. Any tips for converting it to manual choke, or what to do about the failing auto choke? __________________ 1987 Yamaha XT600 2KF (German) STOLEN: RED XL600 in Portland I do heavy-duty textile repair, upholstery, and design/manufacture bags.

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06-08-2010, 08:23 AM	#3
pureliquidhw ^OP n00b Joined: Jun 2010 Location: WI Oddometer: 3	totally. in my infinite wisdom i put the throttle body on backwards and it was stuck half open. Now the throttle works fine, but the engine not so much. The scooter does fine under light throttle loads, but when I rip on it if bogs down. I re-gapped the plug but that didn't fix it. Then, once warm. The engine just quits. I don't know if it was just flooded or if there is some kind of compression issue (please god no). This morning I was told the gas is over 2 years old. I'm surprised it ran at all! I'm going to drain the tank and get a fresh batch of 92 octane petrol as well as some smokeless 2 stroke oil. So basically I'm attacking from all angles. And since it was so hard to find any info on the NX50 i might just post a cleaner version of my trials up top.

06-16-2010, 08:38 AM	#4
ADV scoot Minimalist adventurer Joined: Feb 2010 Location: visalia CA Oddometer: 40	I have a 77 express that I am having the same problem on. My grandmother gave it to me and it had been sitting in her garage for 25 years. I gave it to a guy that has worked on old Honda's for 50 years. He says that the crank seals are bad and the oil from the trans is leaking threw. witch makes it idle ok, but when you get on the throttle it will bog down. He is still having trouble with it. I hope to get it back soon.

06-17-2010, 10:05 AM	#6
pureliquidhw ^OP n00b Joined: Jun 2010 Location: WI Oddometer: 3	I put the throttle cylinder thing in backwards. The carb was on right lol. I finally got new gas in it, but that didn't help. I am running premix, approx 30:1 like you said. I cleaned the carb following the instructions posted online, and tested the float, compression, throttle adjustment, Idle screws were set to OEM recommendations, but all I could get it to do was a crappy idle at full throttle. It looks like the carb is overfilling with gas and it is running too rich. I finally gave it up to a local scooter shop. He quoted me $35 bucks to get her running well (since i already had it running). I'm good with that considering I would be dropping that much on parts that I probably don't need. Thanks for the comments!

07-18-2010, 09:06 PM	#9
romans racing n00b Joined: Oct 2006 Oddometer: 4	Go to www.mopedarmy.com , check piston rings and exhaust for carbon buildup, needs to be cleaned about every 1000 miles for a good running bike, and clean carb pilot and main jets with a micro drill bit, or wire.