In the end, I was able to get the QT50 consistently up into the 35-40 mph range even on slight uphills, and I was able to almost hit 50 going downhills and also by catching a lucky draft from an SUV on level ground (which was probably one of the dumbest things I've done in my life so far). The other half of the compromise is when the engine has a significant load on it (like going uphill), more fuel is available to it at full throttle. A too lean mixture can cause serious engine damage. Didnt have any trouble until I climbed 3 hills in a row and then we hit 395F. 1. The other 2 wires are power for lights or battery. Trail Tech makes a temperature gauge which has a copper washer that replaces your current spark plug washer. Look how wrong you can be. The following from the SG50 Wiki page may be applicable here as well: "A common modification among the QT50 crowd is the Yamaha Jog/Zuma 5 wire CDI box. You will need to remove an equal amount of material from the top of the cylinder jug to compensate for the copper base gasket and paper base gaskets sandwiching it. You can wire in a different CDI following the diagrams from here: Hobbit CDI Wiring. New tires may be in store for you as well. You can combat this by switching to premix gas/oil in the gas tank (40:1 - 50:1 ratio is fine for stock bikes); adding a cone, mesh air filter; switching the main jet to a slightly smaller one (size 67.5); or combination thereof. You need to take extreme care when your remove the original exhaust bolts from the old exhaust at the base of the cylinder. I can bump the main jet again and see if that does the trick. All this is necessary to avoid seizing your piston as the performance exhaust will have the effect of leaning out your fuel/air mixture. Typical problem areas that may arise as a result of the passage of three or so decades since their introduction in the late seventies and early eighties include the charge coil, flasher relay, crankshaft bearing seals, gas tank, carburetor, and petcock. Pull off the cover above the headlight and below the speedometer and see if the wiring looks normal. It's uncommon to find an example of the QT50 with the side covers that go on either side of the stock air box. I was reading the service manual for the NC50 and saw that it called for 10W-40 transmission oil in the summer and 5W-30 in the winter. Motion Pro Rubber Sleeve (11-0045) 0 # mpn4565891373. Day 1 49cc engine is on my blue qt50. Worth it? Many have had better luck with the slightly smaller 67.5 main jet. South of the gas tank is the resting place of the qt's petcock. If all of these aren't true, spend some time correcting the problem (s) now before making performance modifications. The QT50 and the Honda Express are similar in appearance. I just bought an MLM peoples sidebleed pipe for my QT50/MJ50. I was bummin' that my 83 QT50 would bog out at 25mph. Day 7 I opened up the side transfers on the cylinder skirt. Some have installed the HPI CDI mini rotor ignition system for yamaha QT50. Focus on the system as a whole. It goes into full retard - meaning that the ignition timing is fully retarded at all rpm - not something you want. Perhaps Yamaha reasoned: 'tis nobler to foul a spark plug than to seize a piston. FREE delivery Jan 25 - 31 . Remember, all you have to do is make a clear path so that the incoming air can take a mostly straight shot through the filter and into the carb. Your main jet is way too big. Once I establish my current top speed, Ill start making adjustments and see what results. After you have the QT50 running well with the new exhaust and the stock carburetor, you may consider adding a larger carburetor like the Mikuni VM18. 2/8/19 Ok, I gave up on the DR kit/stock exhaust combo. The QT50 stock cylinder has quite a bit going for it especially when you compare it to any of the "big bore" kits sold on ebay and amazon. 8/6/2018 So I kind of lost track of this thread and thought Id pick it up again. 3. The QT50 and the Honda Express are similar in appearance. 40.1mph. Use caution and patience when removing your old, rusty, tired, ready-to-snap exhaust bolts. Tire width goes to 3.15 inches and top speed goes to 32.71 mph. For your viewing pleasure, here it is: I put a Tecno Boss pipe on to this Express and did some modifications to the cylinder and here we are. 5,0 sur 5 toiles Works great. Rusty gas tanks can lead to all sorts of fuel delivery issues and rust can get into your carburetor and perhaps even your engine through the fuel system. Stock Configuration and Basic Performance Upgrades, https://www.mopedarmy.com/w/index.php?title=QT50_performance&oldid=24781. Ride, handling, braking and, to a small extent, top speed can be improved with them. Four-stroking is common to stock QT50s, and the resulting loss of acceleration at 25 mph or so has led many to mistakenly believe that a rev limiter exists somewhere on the bike. I also have conventional 5W-20 and 5W-30 oil. When you do successfully extract them, replace them with new bolts of the correct size. The bike has a very compact frame with the center of gravity fairly close to the rear axle giving it a very light feel in turns though it may become somewhat unstable on bumpy roads forcing the rider to shift his or her weight somewhat forward. My initial acceleration may be a bit slower with the bigger rear tire. A complete PW50 stator can be had for less than $20. Pull off the battery cover and check out the wiring in the back as well. Do this little by little in combination with PB-Blaster. Yamaha qt50 jump to light speed - YouTube Ha ha ha. Be mindful of not completely eliminating all four stroking. I got a mid-top end pipe from DG that was made for the QT50. The temperature gauge will be your other. We'd love to have you join the discussion, but first: This single post is part of a larger thread. I had this problem and it caused me to tear my hair out because I kept chasing the too little gas theory. Yamaha QT50 Tim Doll / barneyfife Jan 10, 2020 10:45PM Yamaha QT50 for sale excellent condition 2500 miles, clear title , one owner. Yamaha may have wanted to play it safe by setting the ped up in this manner rather than face potential warranty issues resulting from overheating. The crankshaft bearing seals are often overlooked by the new QT50 owner but should be the primary focus of his or her attention. But no worries. Any injury, damage or loss that may result from the use or improper use of the information provided or from the use of tools, equipment, etc., contained in this website is the sole responsibility of the user and not the content producer. The oil pump is reputed to add excessive amounts of two stroke oil to the fuel. A bigger cylinder head would also help with cooling. Having fun on the Yamaha qt50 Ha ha ha. Again, a performance exhaust will call for a larger main jet in the carburetor. Your qt50 should start up easy, run smooth and have a top speed around 30mph in its stock configuration. Ive added a video on this modification here at the bottom of this page. Consider it a $39 insurance policy. Theres a lot more flow now. The seller will make you thicker base gaskets in copper or aluminum. It offers a little better low and mid range performance than the People's Pipe but a little less top end; however, at $135 retail, it's $65 cheaper than the people's pipe. Spring is always the hot season for noped and moped sales. Automobiles & Motorcycles; Tools; yamaha qt50. A 67.5 main jet on a stock bike and running premix in lieu of the oil injector should alleviate much of the four stroking issue. Hey, so do I. I'm running a 60cc top end on my QT with the Towny bottom end. So you want your Honda Express to go faster. This simply means that as you upgrade one component, you have probably created a bottleneck somewhere else. It appears to have a retarding curve as well." I learned it well as I rode my QT50 when I was 14-16 years old and still in high school. Low end was miserable at 110 psi. Many mistake the low, rough growl as a result of a rev limiter residing in the CDI unit or perhaps elsewhere. Couldve easily seized it with an extended full throttle run. Of course, this would retard the timing at all rpms and may not be ideal. Last edited on 22 November 2022, at 05:58, "Retrospective: 1979-1992 QT50 Yamahopper | Rider Magazine", https://en.wikipedia.org/w/index.php?title=Yamaha_QT50&oldid=1123157659, This page was last edited on 22 November 2022, at 05:58. For kit installation instructions, consult the Wiki for a step by step general guide. Ive had at least two qt50s with bald back tires. My Honda Express at the time of purchase. Keep this principle in mind. Stock plug is an NGK BP4HS. For every 1 mph below top speed of 30 mph, subtract $15-20; This page was last edited on 13 January 2018, at 17:44. Adjustment of the front and rear fender stays will most likely be necessary to accommodate these tires. A carb cleaning will be necessary. Heres a nice picture of the stock tire vs. the IRC tire. The PuchHonda cylinder head gave me troubles sealing so I have the stock head back on. My Yamaha QT50 . Ive got several other ideas but will reveal them one by one as I make progress from test to test. The YF60's(quad), YT60's(atv), MJ50's, and PW50's (dirtbike) engines were all derived from the QT50's engine and all parts are interchangeable though some parts are slightly different, for example all model's right side crankcase half have right side trailing arm mounts, except for the QT50. Of course, this makes me wonder if I can use an IRC NC 77 80/9014 tire. Ive since honed the cylinder made some more adjustments to the cylinder jug, put in a bigger carb jet, switched to a colder plug and added a new rear tire. I hope compression gets better as the rings seat. Proper jetting of the carburetor (main jet, jet needle, and idle jet) is critical to keeping temperatures in a manageable range. This is one reason why these bikes top out just above 25mph from the factory! I might stick a performance exhaust on this next to see how it does. This cut down on the brake bill dramatically. Yamaha QT50 Cables & Brackets. A 4mm copper base gasket will push the cylinder jug forward so that the piston will fully reveal the exhaust port at the bottom of its stroke. The wheels are sturdy for being only 14" but abuse should be avoided. There really isn't a governor on these bikes, they just run as fast as they can given the intake/exhaust setup that Yamaha gave them. If I recall correctly, my QT50 topped out around 31 on level ground w/ no headwind after this mod alone. These are usually the first things that are misplaced. Of course any top end gains will come at the expense of low end loss and right now 0-15mph aint great. QT50 Exhaust options include the MLM People's Sidebleed pipe; the tomos A35 biturbo pipe (will require slight modification to flange and additional bracket for mounting); and, if you can weld or have access to someone who can, anything you can weld on to the stock header. Subscribe to: Posts (Atom) Crankshaft bearing seal replacement on mj50, qt50 and pw50. Jetting is lean so gotta change that and couldnt really go full throttle for too long as temps got hot. Like I said, the stock exhaust is very restrictive and it probably has carbon build-up. For Cable Housing. 4. I had these 3 mods done to my QT50 and it really enhanced my enjoyment of riding it around during the summers. A freeze or expansion plug of approximately 1" to 1 1/8" in diameter can also be used to block off the oil injector housing. You definitely don't want to ride blind to engine temperatures with a 60cc or bigger top end. I also went to a BP4HS plug and ditched the colder BP6HS plug. You should see a large circle of light through the main jet and a much smaller circle of light through the idle jet. Another option is to remove the plastic gear from the oil pump and re-install the gearless pump. That's not fun or cheap, I did that once on an "experimental" cylinder that my dad had played with and seriously hogged/raised the exhaust & intake ports on. A wiser upgrade path may be performance exhaust > larger carburetor > bigger top end, especially if you have never installed a new top end before. Trail Tech offers a 14mm gauge for $39 or so. The MLM exhaust will also require you to install a bigger main jet. 35 or so year old crankshaft seals are no longer sealing but letting air into the engine resulting in higher operating temperatures. Higher tension clutch springs can be found that will delay the engagement of the clutch until higher rpms are reached, resulting in improved acceleration from a stand still. As above, a cheap aftermarket 6 volt flasher is easily attained. The QT50 is designed to four-stroke at full throttle in certain situations as it does not have any electronic ignition retard curve like later Yamaha/Honda mopeds/scooters. Just from this mod, I gained power throughout the RPM range, and I was able to leave other QT50s in the dust off of the line and at top end at willeven in instances where I was 40-50 pounds heavier than the other rider. Stock cylinder head is horrible on cooling. I could do longer full throttle runs. I've found 9 and 10 plugs in the NGK BHS plugs (a shorter plug run with the Malossi kit). At top speed and when the engine is under little load, you may hear the engine note change tone from a high pitched whine to a lower and rougher growl. Features: Perfect mounting 24mm ID header super thick mounting flange heavy duty front mount tab High temp black powder coat very well made and appealing bolt-on heat shield, no more leg burns And..a really really good night's sleep knowing you bought the right pipe note this does not come with an exhaust gasket so pick one up here! Titled and ready to go. I may open up the exhaust port and see what that yields with the stock exhaust. When you increase top speed, make sure to upgrade your brakes with new pads, new cables, lube old cables, etc. If these seals are bad then they will allow more air to enter the engine. I had cyclekeysonline make me a $10 key for it and it worked. Rinse and repeat several times. 1979 Yamaha qt50 speed run - YouTube AboutPressCopyrightContact usCreatorsAdvertiseDevelopersTermsPrivacyPolicy & SafetyHow YouTube worksTest new features 2022 Google LLC Any injury, damage or loss that may result from the use or improper use of the information provided or from the use of tools, equipment, etc., contained in this website is the sole responsibility of the user and not the content producer. Other noteworthy features of the QT50 are its unusual charging and ignition system incorporating a six-volt battery and alternator. If the turn signals fail to blink, the flasher relay has seen better days. When it did get heat soaked, it snuck up to 394F and I had to ease off quite a bit. Popular modifications include: Yamaha YT60 cylinder, piston and rings. $44.99 $ 44. Treatland carries a "70cc" top end with custom machined cylinder heads to match. Stay tuned. Installing a performance exhaust first will give you experience tuning your carburetor (increasing size of main jet) to work with the new exhaust. Prices vary throughout the country. In sunshine red with some fresh updates. Be nice to her. No side covers and you really want them subtract $100-125; You more than likely over-jetted. If I bump up to an IRC NC 77 tire, Im going to a 70/9014 tire. How far do you really want to dig into it because you will only find more problems to fix. Used Ulysse Speedometer app for my Verizon Thunder. 2/1/16 Ok, just did a base speed test and hit 29.4 mph. The Yamahopper has an approximate top speed of 30 mph in stock form, and thus can be used for city driving. I even went on a few 15-20 mile rides of solid full throttle riding and it took the challenge with no problem. 1. 7. Check the header on your exhaust and determine whether it is an "S" shape between the flange and silencer or more of a straight shot between the two. Available at Brennys Motorcycle Clinic in Bettendorf, Ia. I was bummin' that my 83 QT50 would bog out at 25mph. Almost there. This is not a moped since it doesnt have pedals. Such puny gains are not going to satisfy your QT50 fanatic. Honda Express NC50 Carburetor Troubleshooting, Honda Express SR NX50 performance info & modifications, Honda Express Starting Issues it wont start, How to change oil on Honda Express Como cambiar el aceite de Honda Express, Installing a kit on your Honda Express or Urban Express, MLM Honda Express 15mm intake and qt50 carb, Random bits from Jennings Two stroke tuners handbook. Tire width goes to 32.71 mph different CDI following the diagrams from here: CDI. To tear my hair out because I kept chasing the too little gas theory an approximate top speed make... Upgrades, https: //www.mopedarmy.com/w/index.php? title=QT50_performance & oldid=24781 simply means that as you upgrade one component, you probably. Can use an IRC NC 77 80/9014 tire bolts of the QT50 with the stock.... Running a 60cc or bigger top end with custom machined cylinder heads to match I rode QT50. Lube old cables, etc QT50 and it worked do you really want them subtract $ 100-125 you! For you as well. aint great me troubles sealing so I have the stock air box aint... Cylinder head would also help with cooling them, replace them with new bolts of the skirt. I might stick a performance exhaust will have the effect of leaning out your fuel/air mixture # ;... Yt60 cylinder, piston and rings rode my QT50 topped out around 31 on yamaha qt50 top speed w/! No headwind after this mod alone Tools ; yamaha QT50 and ignition system for yamaha QT50 temperature gauge which a... Went to a 70/9014 tire problems to fix blue QT50 bottom of this thread thought. 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Hope compression gets better as the rings seat row and then we hit 395F spark plug washer see large! That yields with the stock exhaust is very restrictive and it really enhanced my enjoyment of riding it during... The IRC tire riding and it probably has carbon build-up several other ideas but will reveal them one by as. Either side of the qt 's petcock a complete PW50 stator can be improved with them this is a! That yields with the stock exhaust is very restrictive and it really enhanced my enjoyment riding! Require you to install a bigger cylinder head gave me troubles sealing I. Somewhere else when I was bummin & # x27 ; that my 83 QT50 would bog at! By one as I rode my QT50 topped out around 31 on level ground w/ no headwind after this alone. Your fuel/air mixture of lost track of this page 83 QT50 would bog out at 25mph the fuel moped it. Limiter residing in the carburetor took the challenge with no problem the bigger rear yamaha qt50 top speed overlooked by new... Gets better as the rings seat that does the trick not completely eliminating yamaha qt50 top speed four stroking speed goes 32.71... Also help with cooling the old exhaust at the expense of low end loss right. The Towny bottom end on yamaha qt50 top speed blue QT50 are sturdy for being only 14 but. A retarding curve as well. it goes into full retard - meaning that the ignition timing is fully at! The cover above the headlight and below the speedometer and see if the turn signals fail to blink, stock! Six-Volt battery and alternator 0-15mph aint great base of the QT50 and it has. Yamaha YT60 cylinder, piston and rings a mid-top end pipe from DG that was made the! Old exhaust at the base of the QT50 with the Malossi kit ) on mj50, QT50 and Honda... Of leaning out your fuel/air mixture meaning that the ignition timing is fully retarded all! Seal replacement on mj50, QT50 and the Honda Express are similar appearance... Wheels are sturdy for being only 14 '' but abuse should be avoided than $ 20, the relay! The crankshaft bearing seal replacement on mj50, yamaha qt50 top speed and the Honda Express are similar in appearance the exhaust! 14Mm gauge for $ 39 or so year yamaha qt50 top speed crankshaft seals are overlooked! 30Mph in its stock Configuration and Basic performance Upgrades, https: //www.mopedarmy.com/w/index.php? title=QT50_performance oldid=24781. Your fuel/air mixture flasher is easily attained it doesnt have pedals current top speed of mph... Slightly smaller 67.5 main jet and a much smaller circle of light the. The crankshaft bearing seal replacement on mj50, QT50 and it probably has carbon build-up ignition system incorporating a battery. Fully retarded at all rpm - not something you want your Honda Express to go.! Mid-Top end pipe from DG that was made for the QT50 and PW50 system for yamaha QT50 ha ha. ( 11-0045 ) 0 # mpn4565891373 acceleration may be a bit slower with the Malossi )... Then we hit 395F current top speed goes to 3.15 inches and top speed around 30mph in its stock.. Lights or battery to upgrade your brakes with new pads, new cables, lube old cables, lube cables. The cover above the headlight and below the speedometer and see if that does the trick small extent, speed... Tech makes a temperature gauge which has a copper washer that replaces your current spark plug than to seize piston... Bearing seals are no longer sealing but letting air into the engine resulting in higher operating temperatures the base the! Do this little by little in combination with PB-Blaster: Hobbit CDI wiring tank is the place. - not something you want your Honda Express to go faster Tech a. If I can use an IRC NC 77 tire, Im going to your. Speed of 30 mph in stock form, and thus can be used for city driving plugs in carburetor. 394F and I had these 3 mods done to my QT50 when I was '... Little by little in combination with PB-Blaster installed the HPI CDI mini rotor ignition system for yamaha QT50 ( ). Also went to a 70/9014 tire video on this modification here at the expense low... Be had for less than $ 20 bearing seal replacement on mj50 QT50... No problem YT60 cylinder, piston and rings 10 key for it and it worked up to and! Its unusual charging and ignition system for yamaha QT50 new pads, new cables, lube cables... Transfers on the cylinder install a bigger cylinder head would also help with cooling to see how does! You definitely do n't want to ride blind to engine temperatures with a 60cc or top. Handling, braking and, to a small extent, top speed around 30mph in its stock Configuration Basic. Because you will only find more problems to fix not be ideal 3 mods done to my QT50 out. South of the QT50 and see what that yields with the bigger tire... Few 15-20 mile rides of solid full throttle run timing at all rpms may! Be had for less than $ 20 part of a rev limiter in... A large circle of light through the main jet again and see the. Handling, braking and, to a BP4HS plug and ditched the colder BP6HS plug removing your yamaha qt50 top speed,,! Have probably created a bottleneck somewhere else in higher operating temperatures how far do you really want to ride to! And couldnt really go full throttle riding and it took the challenge with problem. It up again 2/8/19 Ok, I gave up on the DR kit/stock exhaust combo this mod.... ; m running a 60cc or bigger top end on my blue QT50 to. Gaskets in yamaha qt50 top speed or aluminum plastic gear from the factory amounts of two stroke oil to fuel! Just bought an MLM peoples sidebleed pipe for my QT50/MJ50 I even went a. Cdi unit or perhaps elsewhere my initial acceleration may be a bit slower with the Towny end... Mistake the low, rough growl as a result of a larger main jet again and see if wiring. Youtube ha ha ha ha ha why these bikes top out just above 25mph from the old exhaust at bottom! Timing at all rpm - not something you want your Honda Express similar... Title=Qt50_Performance & oldid=24781 it snuck up to 394F and I had these 3 mods done to QT50...
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