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I've ported the exhaust on my 79 Honda express now it is slow starting from a stop like some thing is slipping or I just don't have the power it had. I haven't had time to make a tuned pipe could this help? Once I get moving I can get up yo 35mph. Also since I ported the exhaust the engine has a tinny sound I've pulled the head and cylinder off and found nothing wrong, what is the strange sound?
Posted on Sep 16, 2006, 7:04 PM from IP address 24.208.90.112
I have a 1981 QT-50. I have done extensive testing and checking on this unit. It has a new rubber boot from carb to air box, new plug(s), compression will reach 110 PSI if I kick it over several times. The carb has be cleaned and yes the small jet hole is open (clean free of debris), I have tried a 80 and 70 main jet. The oil pump seems to be OK, while running at idle it will (burp) a small amount of oil (less than a drop) about once every two or three seconds. I'm running amsoil synthetic, is that bad, I don't know because it seems to hang around too long, thus the oil soaked plug. I'd like to know what a vaccum gage should read if I put it in the oil injection tube hole (thats the only location to read engine vaccum). Anyway the muffler does not appear to be plugged it has a nice putt-putt-putt, not a hummmmmmm. This moped used to do 28 mph and now I'm lucky to get 20 out of her (this was 10 years ago). I took the reed plate off and noticed some wear on the plastic block and a gap between the reed valves and the plastic block I flipped it over and bolted it together and now have a nice tight seal. The moped is hard to start, I have to use a propane bottle (in the carb) to get her to start. Once running hot she will run and restart hot, when she cools down good luck and I need that propane bottle and a new spark plug. Also the main jet needle has 3 or five locations for the E clip I've tried them all. I should also note that the spec for the spark plug lists a L92YC (champion) this is a (hot) plug the ceramic tip extends past the threads. This plug seems to foul faster that a L86C which is a cold plug the ceramic tip does not extend past the threads. I should also note that I have tried several gaps and .35 seems to work well, what is the factory setting anyone know? What am I missing? Thanks for all replies. JB
Posted on Sep 15, 2006, 4:08 PM from IP address 69.47.87.168
I am not familiar with the QT50, but a fouled plug can be caused by a bad wire from the coil or a bad plug boot,and also you need to run the right plug for it.
Does this have CDI,electronic ignition? If it has points(gap them after cleaning at .014" unless you know otherwise), they may not be giving enough spark, and the plug gap for a points system should be around .022-.024" in my opinion.The electronic ignition can handle a gap of .035" or wider.
Just for a change, run the moped at night on the stand and look for sparking where it shouldn't be.
Never assume a muffler isn't blocked. If the bike has a few thousand on it, go ahead and decarbonize the muffler,and make sure there's no carbon build-up at the cylinder exhaust port.
Do a search on this site and when you get your info., hit `cached' and it will send you right where you need to be. I hope some good Yamaha and Express experts start answering.
You can also go to www.mopedarmy.com and www.mopedriders.com and search it out and take advantage of their repair forums. don-ohio (:^D
Posted on Sep 16, 2006, 6:31 AM from IP address 207.69.139.7
I just bought a 1980 Honda express. It starts great and Idles fin but it will only go 15 mph It has 3300 m on it. I am new to moped so, any help would be greatly apreciated.
Posted on Sep 12, 2006, 4:17 PM from IP address 66.41.150.169
I took my muffler off and soaked it for a day in safty fluid, It's as clean as a whistle. I even sand blasted and painted it with High temp paint. I took the carb off and cleaned it well. got little wires and poked all the jets and blasted it with carb cleaner. removed gas line and installed a clear gas line with a tiny briggs and straton fuel filter. changed the gas. I have a good blue spark with the gap at .22 thousands. I still can only go 15mph. I haven't adjusted a thing on it yet. any suggestions?
Posted on Sep 14, 2006, 6:54 PM from IP address 66.41.150.169
You have to KNOW that the muffler is clean and carbon isn't blocking it. I don't think safety fluid will clear hard carbon very quickly.
Also there can be blockage at the very exhaust port, where the muffler bolts on. I've gotta go pour about 70 yds. of concrete right now, but I'll be back tonight. don-ohio (:^D
Posted on Sep 15, 2006, 2:47 AM from IP address 207.69.137.39
the muffler is clear you can blow right through it. I even ran it with out the muffler and there is no change. I cleaned the exhaust port in the cylinder also. please help dose anyone have a bottom veiw of the carb body to point out the various ports and what to look for? Thanks
Posted on Sep 15, 2006, 3:07 AM from IP address 66.41.150.169
Too full of oil will slow `em down,as will dragging brakes.
This isn't an Iowa `ped is it? They were slower because of Iowa law.
What's your compression reading? You need 90-100 lbs. when you check it with throttle open.
You checked the piston and rings and for scuffing of cylinder walls?
There is a passage hole that is easy to miss when cleaning the carb. on some Expresses. When you look above where the float is, at the top of inside the float chamber, there is a tiny hole that when I poked a wire thru it and sprayed carb cleaner thru it, made an Express run really well.
I wish I could be more help, but Whiz, and Zippy and some others are much better on Expresses than myself.
Keep us informed! don-ohio (:^D
Posted on Sep 15, 2006, 8:00 PM from IP address 207.69.139.148
On your advice Don I started looking at the head,cylinder and piston. I removed the head and cylinder and found the exhuast port nearly blocked!!! This was the second layer I found. I first cleard on out where the muffler mounted to the cylinder head and this one was right flush with the cylinder wall. I cleaned everthing with a little scrapper and brake cleaner. coated evrything with a ligh layer of oil and put it back togather. Because I went through every thing else( carb, muffler, new spark plug, ect.) trying to solve this problem my moped is running top notch and my daughter should enjoy for a few years. Thanks for all your help Don!!!
Posted on Sep 16, 2006, 11:27 AM from IP address 66.41.150.169
I have a 1983 Honda Express NC50 that needs to have the throttle cable syncronized to the oil pump timing marks. I can not see what marks to use. The manual on line looks differant than my setup. Can anyone help me identify the correct timing marks for full throttle setting? Maybe send me a photo or sketch.
Thanks
Roger
Posted on Sep 10, 2006, 4:19 PM from IP address 63.27.154.124
I have a 1980 express 2 w/ a big bore kit & bi-turbo exhaust ( high mounted ) i installed a colder stage plug. #81 main jet, same set-up as this guys ( http://expresslymopeds.50megs.com/70cc.html ) My issue is starts up , idles perfectly but it wont accelerate ( massive surging ) cant get it to go ... any help on carburator set-up, type of jet i should be using, or even an aftermarket carb company would help ...txs guys
Posted on Sep 6, 2006, 6:21 PM from IP address 68.9.229.77
I have a 1980 express 2 w/ a big bore kit & bi-turbo exhaust ( high mounted ) i installed a colder stage plug. #81 main jet, same set-up as this guys ( http://expresslymopeds.50megs.com/70cc.html ) My issue is starts up , idles perfectly but it wont accelerate ( massive surging ) cant get it to go ... any help on carburator set-up, type of jet i should be using, or even an aftermarket carb company would help ....
Posted on Sep 6, 2006, 6:16 PM from IP address 68.9.229.77
i have 1978 nc50 honda express. it runs well all the way until you give it full throttle, then when it hits 17MPH. or so, it starts to sputter. i was wondering if the problem could be a carb. setting that's a little off, or something like the timing being a little off. any help would be greatly appreciated.
thanks
Posted on Sep 4, 2006, 5:59 PM from IP address 24.30.230.140
i'm pretty sure the choke is opening all the way. it does not have an air filter at this moment, but i'm going to get one soon. and, how to do u go about un-plugging the exhaust if that is the problem?
thanks
Posted on Sep 13, 2006, 8:07 PM from IP address 24.30.230.140
This is a bolt-on hop-up kit for a 1977-1983 honda express NC50, express II NA50, or Urban express NU50. It is handmade and one of kind. It includes a custom made chrome k&n style air filter and chrome expansion chamber exhaust pipe w/ mounting harware. The kit will add speed, style and sound to your honda express, express II, or urban express. It is also gaurnteed to add at least 5 mph to the top speed of any year stock express.
I'm asking $200 firm, took me about over 8 hours to make and over $100 in parts (not to mention, good luck finding one these anywhere else in the world). I will also install the kit and tune the carb on your bike for an extra $50 (bike must be running well prior to installation). I'll also give you a $20 credit for your old stock exhaust pipe regardless of condition.
Be the only kid on your block with a custom express!
email for purchase or photos birddog527@aol.com
Posted on Sep 2, 2006, 2:27 PM from IP address 67.165.252.236
Does any one have rear wheel bearings for my 79 honda express II NA50 or know the bearing numbers. my has to be replaced and I would like to have them on hand before I tear into it.
Posted on Aug 31, 2006, 6:20 PM from IP address 24.208.90.112
My 79 NA50 express starts good but sputters when you give it gas then smooths out and runs up to speed then it will sputter and lose power if I back off the gas and hit it again it will run smooth for a bit and sputter again Ive got the carb set at throttle 2 turns out and air 1and 1/2 turns out I've got a NGK BP4HS spark plug and I'm using 91 octane fuel I,ve got a cone shaped paper air filter that I adapted it lets in quite a bit more air that the stock filter.
Posted on Aug 26, 2006, 3:22 PM from IP address 24.208.90.112
My 79 NA50 express starts good but sputters when you give it gas then smooths out and runs up to speed then it will sputter and lose power if I back off the gas and hit it again it will run smooth for a bit and sputter again Ive got the carb set at throttle 2 turns out and air 1and 1/2 turns out I've got a NGK BP4HS spark plug and I'm using 91 octane fuel I,ve got a cone shaped paper air filter that I adapted it lets in quite a bit more air that the stock filter.
Posted on Aug 26, 2006, 3:08 PM from IP address 24.208.90.112
I need help, the sparkplug isn't sparking on my 1978 honda express moped and I checked all the connections and I charged the battery and it won't spark. Some body help me!!
Posted on Aug 18, 2006, 5:18 PM from IP address 71.113.4.57
I've got the manual but it doesn't make sense to me do I check them on the "F" or the the "T" line. also at what point should the points be open the furthest? How do I adjust them to the F or T
Posted on Sep 23, 2006, 3:32 PM from IP address 216.160.238.132
Question Quote-`I've got the manual but it doesn't make sense to me do I check them on the "F" or the the "T" line. also at what point should the points be open the furthest? How do I adjust them to the F or T'
ANSWER:The points start to open at the F line. To adjust them, you do it at T or at the widest point before they go shut again.Just pass a feeler gauge thru them at TDC or where they open widest, and see what the gap is.
The wider the gap, the faster it makes the timing. don-ohio
Posted on Sep 24, 2006, 7:43 PM from IP address 207.69.138.7
That helps a lot. Thanks. I feel stupid. I knew that stuff f=fire T=TDC=top dead center. Thanks for the help though. I think my timing is way off or my ignition (condenser) coils are bad. We will see.
I am a little confused about how to check the condesor. in the manual it shows three different ways with a ohm meter. I get good on one of the three ways. Do all three ways have to work in order to determine if it is good?
Greg
Posted on Sep 26, 2006, 9:49 PM from IP address 71.35.197.79
The ignition coil can be checked easily with an ohmmeter, but the condensor gets checked a certain way.
You use an ohmmeter,but in one part of the test, the voltmeter,I believe is used. I'd have to read up on it. I'm not an electrical guru at all.
Do the test just like it's written and see what happens.Maybe some electrical guru will help you out?
I'll try to look at it later. don-ohio (:^)
Posted on Sep 27, 2006, 8:04 PM from IP address 207.69.137.20
I have a 1979 Honda express II NA50 that I'm rebuilding I got it started and the idle set pretty good, I let it warm up, ajusted it a little more then I rode it to the end of the block a back, it was running a little fast I went to get a screw driver and as I stepped away it started racing I tried to ajust it but it died now it will not srart, I checked the throttle cable it is free and smooth, I pulled the carb. and checked every thing and that all looks good I was running with out the air cleaner? Whats going on.
JOE
Posted on Aug 15, 2006, 7:39 AM from IP address 24.208.90.112
Did you have the fuel valve open? Then maybe the petcock screen is plugged in the carb, or more likely, the fuel cap isn't venting or the lever isn't set to `vent'. don-ohio
Posted on Sep 12, 2006, 5:51 PM from IP address 207.69.137.9
My 79 honda express starts a little hard so I pulled it air filter off after I had run it and then let it set, there was a gas puddel in the bottom of the air intake, it runs good and the idle seems to be set right what could be wrong?
Posted on Sep 22, 2006, 7:23 PM from IP address 24.208.90.112
Hard starting can be a LOT of things,not just the carb.,but for an Express to run right, the carb needs to be adjusted.
A starting point I use is the bottom screw(air/fuel screw just under the idle screw i think.....I turn it in snug and then back it out one and a half turns.
Always make sure you have a good spark plug and fresh fuel. Then,too, the carb. could be flooding. get into the habit of shutting the fuel tank petcock every time you stop the bike and see if that helps. If it does,the needle valve isn't shutting off flow from the tank and the carb's flooding,making it hard to start. don-ohio
Posted on Sep 27, 2006, 8:14 PM from IP address 207.69.137.20
Back in 1950 51 my Dad got me a motor bike it had a Briggs & Stratton engine under the seat it also had throttle peddle and brake peddles it was pretty low slung the tires were a little bigger than a bicycle and the spokes were heavier. I don't remember what the hp was but that bike could move. Can any one tell me what it was who made it? Thanks Joe
Posted on Aug 13, 2006, 6:15 PM from IP address 24.208.90.112
Sorry I fount out it was a Safticycle GREAT old bike I loved it I would tear around those country roads terrorizing chickens andout running dogs, my dad taught me how to do maint. I think I changed oil in thst thing every week. I also hoarded spark plugs I didn't know one plug from another so I'd just keep trying till I got one to fit.
Posted on Sep 24, 2006, 9:24 PM from IP address 24.208.90.112
