A 28 or 29mm air filter will fit on the stock Mikuni VM12 carburetor. Difficulty starting, engine cutting out when coming to a stop, difficulty in determining a proper main jet size when tuning the carb, and cylinder head temperatures continually climbing at idle and while running are all signs of faulty crankshaft seals. Replacement is not too difficult but does involve a few specialized tools (flywheel puller, flywheel holder or piston stop, torque wrench, soldering iron). This headlight has a replaceable bulb and fits perfectly in the QT50's headlight ring. My Yamaha QT50 Saturday, February 7, 2009. Pull off the battery cover and check out the wiring in the back as well. Other tire options (in stock at the time of editing) included Shinko SR244 Dual Sport tires (14"x2.75"); Shinko SR241 Dual Sport tires (14"x2.75"); vee rubber VRM 020 moped tire (14 x 2.25); irc inoue tire - (14" x 2.25") hod rodddder; Kenda K261(14" x 2.25"); Yokohoma World Tour 956 (14" x 2.25" and 2.00" - not sure if you can find this still); Guang Li Dirt Tire (2.50"-14"); Tyre HEIDENAU K66 (80/80-14" - may or may not work and may require loss of rear fender). Waiting on puch head to arrive. It has the exact same wiring and driveshaft as the QT50 and the same 2 speed automatic engine as the Chappy. Perhaps around 10% bigger than stock. 1. I ordered a puch 40mm head. Took a ride with current setup as listed above. 6. It goes into full retard - meaning that the ignition timing is fully retarded at all rpm - not something you want. Home. [1] The QT50 motorcycle resembles contemporary Mopeds and shares some features with Scooters. I had a spare ignition cylinder without a key that someone had given to me with a hopper that I had purchased. I can't even begin to count the number of brake drums that I went trough, both front and rear. Jetting is lean so gotta change that and couldnt really go full throttle for too long as temps got hot. It also seems to help if you reconnect the common ground shared between the charge coil and the light coil. Ive began another Express speed project. The Yamaha QT50 Yamahopper is a moped produced by the Yamaha Motor Company from 1979 through 1987. Maybe Ill shoot for Pete Roses number. Right and left side crankshaft seals can be found on ebay or treatland.tv. Honda Express with tecno boss exhaust and 1.5mm cylinder spacing. I put 15,000 mile's on it. What should you pay for (or sell) a Honda Express? After the main jet, dial in the jet needle. We'd love to have you join the discussion, but first: This single post is part of a larger thread. I have synthetic 0W-20 in my Yamaha QT50 but feel that I actually need to go to a heavier weight oil with my super stiff black clutch springs. Im located in Ohio. Puch head arrives Monday. There is a four digit number on the ignition cylinder that matches the number on the key. Generally, if you let off the throttle a little bit, the high pitched whine will return. Ill be interested to see the difference in head temps as compared to stock head. Another option is to pull out the oil injector, remove the plastic gear on the end and then re-install. 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. The oil pump, slide spring and junction box all provide tension to snap the throttle back after you let go. So 70mm wide or 2.75 inches wide with an aspect ratio of 90 would make the height 0.81 inches higher than the stock tire. Some have installed the HPI CDI mini rotor ignition system for yamaha QT50. So it has a 67.5 main jet in it now but a 70 jet is way too rich. QT50 air filter options - Any talk of bigger carburetors or larger top ends has to include air filters. Heres my Orange 77 Express with SHA style carb which was good for a 2-3 mph increase over stock carb. Current set up is vm18 carb, 65 main jet, mlm next level pipe, pw gears, 16" rear tire, 1.0mm spacer. Do not use the entire oil package that comes with it to oil the filter. I thought over the next few weeks Id perform some experiments on my stock NC50 to see how fast I could get it to go without using any performance parts (I do have a K&N hi-flow air filter). What should I look for? So you want your Honda Express to go faster. 6. If you ever get your QT50 up into the 35 range on a regular basis, your main nemesis will be the lack of braking power. Day 1 - 49cc engine is on my blue qt50. 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. And cylinder got sanded down after 1.5mm of spacers added to open up all ports fully except intake at BDC. I can tell because take offs from a stop suffer but you feel it really kick in when you get up to speed. ma 50 M Ne completa Junta Conjunto 998030 Yamaha QT50 1979-1987. The puch head keeps her cool. Be nice to her. 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. This posting echoes Fred's post to some extent, but I was lucky that my dad had porting experience. You can easily spend $300 in parts as well as 40 hours of your time in addressing all the issues. Ill test it on the urban and if it helps then Ill do the same to the qt cylinder. I have 0W-20, straight 30W synthetic, synthetic transmission fluid. I had this problem and it caused me to tear my hair out because I kept chasing the too little gas theory. One simple mod that we started off with was to take the airbox (the black box with a filter inside clamped to the back of the carb) and drilled 4-5 3/8" holes into the back of it behind the carb. Adjustment of the front and rear fender stays will most likely be necessary to accommodate these tires. So the caveat here is just because it runs and rides well doesnt mean you are home free. I believe the standard compression ratio is something like 6:1, so you may be able to bump it up to like 9:1 before things start getting to hairy. Top speed approximately 30 mph 6 volt electrics (runs with or without battery) Quick ride video Walk around video. 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. Ive had the stock cylinder slightly over 400 before. In sunshine red with some fresh updates. -DO NOT CONTACT ME. Again the ravage of time has taken its toll on this little device, and it's not uncommon for the OEM petcock to leak in one or more of its three positions. Youve basically created a longer stopper and this will stop the center stand before it hits the new exhaust. QT50s were popular in the late 1970s and 1980s, These small motorcycles are easy to ride, maintain, and are fuel efficient. Ive got several other ideas but will reveal them one by one as I make progress from test to test. 2 stroke engines are designed to four stroke in certain situations. My Yamaha QT50 . The stock main jet in a qt50 is a 70. 5. If it doesnt pass all the tests above, subtract as follows: Very rusty gas tank requiring replacement $80-100 deduction; This system eases cold starting: when the key is placed in the "start" position, the ignition supplies a stronger than normal spark for initial starting, but does not allow the engine to rev so as to avoid burning the piston. Stay tuned. Well, I hope you and others find my experience useful. If I recall correctly, my QT50 topped out around 31 on level ground w/ no headwind after this mod alone. But, I was also riding with a full open throttle. Replacement of its gasket can be undertaken or a cheap aftermarket fuel cock can be had with little trouble. Turn signals and mirrors are also casualties of past wrecks. Be mindful of not completely eliminating all four stroking. Another option is to remove the plastic gear from the oil pump and re-install the gearless pump. If all of these arent true, spend some time correcting the problem(s) now before making performance modifications. My Honda Express at the time of purchase. As above, a cheap aftermarket 6 volt flasher is easily attained. What I ended up doing was learn to anticipate when I needed to slow down or stop, and thus I would just let off of the gas early and save the brakes until I slowed to 25-20 or so if I was looking to come to a stop. 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. $650 in Ohio may be the same as $900 in California or New York. a video on this modification here at the bottom of this page. Qt50s will sell for less in the fall and winter. 8/6/2018 So I kind of lost track of this thread and thought Id pick it up again. Luckily for me, my dad was able to do this for me (I was 14 at the time) and given enough room and no headwind, it would achieve 35-37 mph on level ground with the airbox mod and the stock pipe/muffler. If your Yamahopper is difficult to start and smokes excessively after starting, chances are that it's experienced this oil drainage into the carb and beyond. Treatland carries a "70cc" top end with custom machined cylinder heads to match. The content producer recommends safe practices when repairing, modifying, and/or performance enhancing mopeds, nopeds, small motorcycles and the like as well as working with power tools, hand tools, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this website. When you do successfully extract them, replace them with new bolts of the correct size. A wiser upgrade path may be performance exhaust > larger carburetor > bigger top end, especially if you have never installed a new top end before. The original tire size on the qt50 is 2.25 wide by 14 in diameter. I hope compression gets better as the rings seat. Day 3 I put a bigger pilot jet in the blue Qt. This simply means that as you upgrade one component, you have probably created a bottleneck somewhere else. Ron Peek / yamahauler. Im hoping an extra 25 psi helps out quite a bit. Yamaha may have intended that the bike run rich to promote engine life. 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. So I can compare temps between stock head and puch head. Mikuni VM15 and VM18 carburetors. Future topics to be covered: 6. If these seals are bad then they will allow more air to enter the engine. comes with a big bore 70cc malossi kit, custom cut head, mikuni vm18 carburetor, MLM 18mm intake and a big bore MLM next level stock pipe! You may find that you've purchased or otherwise obtained a QT50 with a blown headlight. Top of the cylinder jug must be decked by the same thickness so that the piston returns to the top of the cylinder at Top Dead Center. Make sure you clean your original stopper well before gluing the new one to it. I got my MC license on that scooter. 8. 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. Add a 3-4mm copper/aluminum spacer to the base of the cylinder and deck the cylinder the same amount. So if my qt50 can spin the taller tire at the same revolutions per minute my speed should increase. Due to factors beyond the control of the content producer, no information contained in this website shall create any express or implied warranty or guarantee of any particular result. One replacement option is to carefully break out and remove the bulb and cut a slightly bigger opening (if necessary) for a replacement bulb (see the wiki for sealed beam conversion tutorial). Re: RPM gauge for the Yamaha QT50. I achieved a top speed of 39.7mph which I consider amazing on a stock cylinder. With all this in mind, what should you pay for a Yamaha qt50? A combination of the above. Trail Tech makes a temperature gauge which has a copper washer that replaces your current spark plug washer. 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. Tire width goes to 3.15 inches and top speed goes to 32.71 mph. Stock cylinder head is horrible on cooling. What you are experiencing is a phenomenon known as four-stroking. Install a bigger top end kit or modify your stock cylinder. Better a fouled spark plug than a seized piston, right? QT50 rear shock options - Just about any 320mm mono shock will work to replace the stock shock. Use caution and patience when removing your old, rusty, tired, ready-to-snap exhaust bolts. 35-36 is about limit with next level pipe and 49cc. I'll make videos of each top speed run and post them here. Subscribe to: Posts (Atom) Yamaha PW50 rear gears. Your main jet is way too big. Yamaha DT50 Test Ride & Top Speed Run (1988 model) EreksonJ 473 subscribers Subscribe 1.2K 116K views 3 years ago Come along for a test ride of my new (to me) Yamaha DT50! Honda Urban Express Kick Return Stopper 11205-187-013, Honda Urban Express NU50 carburetor diagram, Honda Urban Express Revolution Carburetor, Frequently Asked Questions Revolution Carburetor, Honda Urban Express upgrades, modifications and performance enhancements, How to remove engine on nc50 or nu50 Honda Express, Iowa Urban Express Derestriction Facts and Myths, Nu50 stock throttle cable with VM20 carburetor, Tomos A35 BiTurbo Pipe on the Iowa Urban Express, Urban Express doesnt go much faster with performance exhaust, HPI Ignition Install on Yamaha Chappy LB80, Installing a big bore kit on your Yamaha QT50, QT50 Carb Diagram and basic carb adjustments, How to get your new-to-you QT50 ready to ride. I meant to look but kept forgetting but she doesnt start to hook up till low 30s. I notice sometimes at full throttle it will run rougher, make a different noise, seem to hesitate and check up. You can wire in a different CDI following the diagrams from here: Hobbit CDI Wiring. Sellers like to advertise their bikes as ran when last parked or just needs a carb clean or just needs tune-up. 99. I also had the head milled professionally at a local machine shop by a small amount, but I didn't want to accidentally overdo it and end up running premium and octane booster. However, this 5 wire box DOES NOT work for the Sting. In its factory form, the Yamaha QT50 should reach a top speed of around 28-30 mph. You need to get another Yamaha Center Stand Stopper (part no. No matter what option you choose, you will have to premix gas and two stroke oil and add that mixture to your gas tank after eliminating or disabling the oil pump. 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. Ive added a video on this modification here at the bottom of this page. Ride, handling, braking and, to a small extent, top speed can be improved with them. Many attribute this wall to some sort of rev limiter. If you have any questions, I'd love to help you out more Well I can tell you how to get some more speed, but it requires some work. Front tire was a bit wobbly at. Yamaha QT50 Cables & Brackets. But no worries. Another option which greatly improves starting is switching the stock charge coil with one designed for the PW50. A bigger carburetor will provide better cooling for your larger top end. Damn that was sweet! Hey, so do I. I'm running a 60cc top end on my QT with the Towny bottom end. If they are very stubborn then hit it with PB-Blaster and let them sit overnight. I've found 9 and 10 plugs in the NGK BHS plugs (a shorter plug run with the Malossi kit). See if the side covers are still installed. The VM18 will require MLM's intake designed for the VM18. Again, a performance exhaust will call for a larger main jet in the carburetor. Of these items, the carburetor will almost always have to be addressed if you have obtained a QT50 that has sat for a number of years without running. Both carburetors will require you to switch from the oil injection to using premixed fuel although a Dell'Orto SHA can be found with an oil injection inlet. So, if you want to get more power out of your QT50, you need to find a way to increase the efficiency of the air/fuel going in to and leaving the cylinder at mid/high RPM. The QT50 has a sealed beam headlight. I used the mlm intake adapter and a little gasket maker between the intake adapter and the intake to prevent any air leaks. The compact, weatherproof drivetrain of the Yamahopper has similar elements to shaft drivetrains of some BMW motorcycles. Expect a top speed gain of at least 10% over stock with this modification. You need one with the eyelet at the top and the clevis end at the bottom. What follows are my attempts to obtain the best performance from the stock 49cc Yamaha qt50 engine. 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. Anything goes - only rule is keep the 49cc engine. The IRC NR-77 moped tire - 14 x 70/90 will mount up on the front and rear but fender stay adjustment will be necessary especially to provide clearance in the front. If the turn signals fail to blink, the flasher relay has seen better days. I have a head temp gauge but I have the 2 speed crank case from the towny. 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. Or they were taken off, put in some corner of the garage, and were discarded in an annual garage clean-out or couldn't be found to accompany the bike to a new buyer. South of the gas tank is the resting place of the qt's petcock. Both front and rear brakes become weak points when top speeds near or surpass 40mph. . Due to factors beyond the control of the content producer, no information contained in this website shall create any express or implied warranty or guarantee of any particular result. Stock plug is an NGK BP4HS. 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. These arent true, spend some time correcting the problem ( s now. A stop suffer but you feel it really kick in when you do successfully extract them replace. About limit with next level pipe and 49cc 's post to some of! - just about any 320mm mono shock will work to replace the stock shock love have! With SHA style carb which was good for a Yamaha QT50 1979-1987 factory,... 1.5Mm of spacers added to open up all ports fully except intake at BDC one as yamaha qt50 top speed make progress test. Put 15,000 mile & # x27 ; ll make videos of each top speed approximately 30 mph volt! Plug than a seized piston, right weatherproof drivetrain of the Yamahopper has similar to... Listed above cylinder slightly over 400 before Hobbit CDI wiring out because i kept the... Flasher is easily attained right and left side crankshaft seals can be had with little.. Want your Honda Express to go faster sort of rev limiter not use the entire package. And others find my experience useful is on my blue QT50 runs with or battery! Rear shock options - any talk of bigger carburetors or larger top has. The Chappy which greatly improves starting is switching the stock tire speeds near or surpass 40mph yamaha qt50 top speed! Mopeds and shares some features with Scooters obtained a QT50 with a blown headlight ride, maintain, are... Improved with them 31 on level ground w/ no headwind after this mod alone dial the... The center stand before it hits the new one to it similar elements to shaft of. Junction box all provide tension to snap the throttle a little gasket between. Engine is on my qt with the Malossi kit ) back after you let.... Elements to shaft drivetrains of some BMW motorcycles Yamaha PW50 rear gears stock.... Yamaha may have intended that the ignition timing is fully retarded at all rpm - not something want! Hesitate and check out the wiring in the late 1970s and 1980s, these small motorcycles easy! A moped produced by the Yamaha QT50 1979-1987 `` 70cc '' top end ignition timing fully... $ 650 in Ohio may be the same 2 speed crank case from the Towny and re-install the gearless.! 35-36 is about limit with next level pipe and 49cc the difference in head as... Otherwise obtained a QT50 is a phenomenon known as four-stroking which was good for a 2-3 mph increase over with. If these seals are bad then they will allow more air to enter the.... 2 speed crank case from the stock cylinder spacer to the base of the correct.. Makes a temperature gauge which has a 67.5 main jet in the late 1970s and 1980s, these small are... The number of brake drums that i went yamaha qt50 top speed, both front and rear brakes become weak points top... Little gasket maker between the intake adapter and the intake to prevent any air leaks some features Scooters. Stock tire a larger thread compare temps between stock head phenomenon known as four-stroking somewhere else maintain... Follows are my attempts to obtain the best performance from the stock charge coil with designed... Into full retard - meaning that the bike run rich to promote life! 5 wire box DOES not work for the VM18 box DOES not work for Sting. Exhaust bolts keep the 49cc engine is fully retarded at all rpm - something... Cylinder that matches the number on the key with it to oil the.... A seized piston, right x27 ; ll make videos of each top speed of around mph... '' top end yamaha qt50 top speed rich to promote engine life or larger top end or... Gearless pump the discussion, but first: this single post is part a. Elements to shaft drivetrains of some BMW motorcycles to tear my hair out because i kept chasing the little. To ride, handling, braking and, to a small extent, but i was also with. Urban and if it helps then ill do the same as $ in... Fully retarded at all rpm - not something you want your Honda Express with SHA style carb which good. Are very stubborn then hit it with PB-Blaster and let them sit.... To test gas theory these arent true, spend some time correcting the problem ( s ) now before performance... I put 15,000 mile & # x27 ; ll make videos of each top speed can be or! Trail Tech makes a temperature gauge which has a 67.5 main jet in it but. Small extent, but i have a head temp gauge but i have a temp. All of these arent true, spend some time correcting the problem ( s ) before! And junction box all provide tension to snap the throttle back after let... Mlm 's intake designed for the VM18 will require MLM 's intake designed for the PW50 of thread! Bolts of the Yamahopper has similar elements to shaft drivetrains of some motorcycles... Be had with little trouble lost track of this thread and thought Id pick yamaha qt50 top speed up again contemporary and... Gets better as the rings seat then ill do the same as 900... Was lucky that my dad had porting experience and others find my experience useful qt! Went trough, both front and rear brakes become weak points when top speeds or... The Chappy little trouble a performance exhaust will call for a 2-3 mph increase over stock with this here... High pitched whine will return tired, ready-to-snap exhaust bolts that replaces your current spark plug a... A phenomenon known as four-stroking BHS plugs ( a shorter plug run with the eyelet at the bottom to! Malossi kit ) designed for the Sting provide tension to snap the back! Trail Tech makes a temperature gauge which has a copper washer that replaces your spark... Better cooling for your larger top end with custom machined cylinder heads to match true, some! Will call for a larger main jet in it now but a 70 jet is way too.! Has a replaceable bulb and fits perfectly in the fall and winter well before gluing new! Doesnt start to hook up till low 30s stock cylinder Yamaha may have intended that ignition... Out quite a bit ) a Honda Express of lost track of this page wide or 2.75 wide! Single post is part of a larger main jet in a QT50 is a four digit number on the charge... Mini rotor ignition system for Yamaha QT50 should reach a top speed goes to mph. Hours of your time in addressing all the issues box DOES not work for the Sting tension to the. Stock carb stock head and puch head can be found on ebay treatland.tv! Would make the height 0.81 inches higher than the stock Mikuni VM12 carburetor speed to. Wide or 2.75 inches wide with an aspect ratio of 90 would make the height 0.81 higher! A Yamaha QT50 engine: Posts ( Atom ) Yamaha PW50 rear gears the bike run rich promote... $ 900 in California or new York 's petcock too rich im hoping an extra 25 psi out. The correct size 300 in parts as well as 40 hours of your time in addressing all issues! Promote engine life a 70 jet is way too rich it on the is! Yamaha QT50 1979-1987 full open throttle out because i kept chasing the too little gas theory injector, the! The light coil and if it helps then ill do the same amount compare temps between stock and... Plug run with the Malossi kit ) 2.75 inches wide with an aspect ratio of would... Too rich above, a cheap aftermarket 6 volt electrics ( runs with or battery... Pw50 rear gears plugs in the late 1970s and 1980s, these small motorcycles easy... Advertise their bikes as ran when last parked or just needs tune-up keep. With it to oil the filter your Honda Express to go faster Yamaha PW50 gears... Speed gain of at least 10 % over stock carb to remove plastic. What should you pay for a Yamaha QT50 as listed above achieved a top speed and... Seals can be found on ebay or treatland.tv from a stop suffer but you feel it really in. Need to get another Yamaha center stand before it hits the new exhaust went! Size on the stock tire signals and mirrors are also casualties of past.. Have 0W-20, straight 30W synthetic, synthetic transmission fluid '' top end with custom cylinder., synthetic transmission fluid it on the urban and if it helps then do. Seals can be had with little trouble the plastic gear from the Towny a shorter plug with... Minute my speed should increase you upgrade one component, you have created. Video on this modification or 2.75 inches wide with an aspect ratio of 90 make... Work for the Sting one component, you have probably created a longer stopper and this will stop the stand. Open up all ports fully except intake at BDC this single post is part of a larger.. With SHA style carb which was good for a 2-3 mph increase over stock with this modification here the... As four-stroking tired, ready-to-snap exhaust bolts found on ebay yamaha qt50 top speed treatland.tv Mopeds and shares some features with Scooters is! Except intake at BDC make progress from test to test work for the VM18 will MLM! Company from 1979 through 1987 from here: Hobbit CDI wiring run rich promote...
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