Didnt have gps on today. So, in essence, it would be getting too little fuel. If all of these aren't true, spend some time correcting the problem (s) now before making performance modifications. The rear brakes tend to be weak on this bike. I just bought an MLM peoples sidebleed pipe for my QT50/MJ50. Many have had better luck with the slightly smaller 67.5 main jet. I also went to a BP4HS plug and ditched the colder BP6HS plug. If it will do its top speed of 29-30 mph, youre in luck. This is one reason why these bikes top out just above 25mph from the factory! Or fastest delivery Jan 20 - 24 . A larger carburetor may even be a better choice than the stock carburetor with a larger jet. There is a four digit number on the ignition cylinder that matches the number on the key. 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. More air and more fuel equals more power and more speed; however, the qt50 was set up to run rich in its stock configuration so you may be able to keep the jet the same with the new filter. The QT50 and the Honda Express are similar in appearance. 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. Most of the parts for the QT50 are still available from Yamaha dealers. Youll think your qt is not getting enough gas because it stalls. This part is used to reduce the degree of performance for your motorcycle, for yamaha. At the time it died out, it was still accelerating! These bikes like most Japanese bikes of the time came with excellent finishes in both the paint and chrome, though the plastic parts on many of these have deteriorated over the years. Ive added a video on this modification here at the bottom of this page. Commentaire fait aux tats-Unis le 10 novembre 2019. 4. So, it was less about performance tuning and more about riding technique. No title subtract $150-$250 (although you can register and get plates through Vermont so lack of title may not be so important or you may be in a state that doesnt require title); To see our full inventory go to brennys dot com. This posting echoes Fred's post to some extent, but I was lucky that my dad had porting experience. Several methods are outlined here at mopedarmy.com. Better a fouled spark plug than a seized piston, right? If the bike doesnt run, make sure you can push down the kick start with ease. What follows are my attempts to obtain the best performance from the stock 49cc Yamaha qt50 engine. Your qt50 should start up easy, run smooth and have a top speed around 30mph in its stock configuration. After the main jet, dial in the jet needle. Almost all states require title to obtain license plates and registration. This does not mean that all four stroking is bad. Take a flashlight and take the lid off the gas tank. I was bummin' that my 83 QT50 would bog out at 25mph. . Another option is to obtain a headlight for a Honda C70. Yamaha Yamahopper qt50 top speed run, hang on! What should you pay for (or sell) a Honda Express? I cleaned up the transfers on a Honda cylinder like the pic above. 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. Ok, I changed the transmission oil to 5W-30 and lost 0.9 mph. And Im happy to buy a non-runner because you often have to put as much into a running bike as a non-running bike. I solved it by going from a 102.5 jet to an 87 and finally to an 85 main jet. Idling at stop signs doesnt really bring the temperature down much. Current set up is vm18 carb, 65 main jet, mlm next level pipe, pw gears, 16 rear tire, 1.0mm spacer. dead battery subtract $25; Reply Stephen Keller / keller_stephen Jan 10, 2020 11:49PM Price? 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. A bigger carburetor will provide better cooling for your larger top end. Mine changes gears . The Yamahopper has an approximate top speed of 30 mph in stock form, and thus can be used for city driving. Web designers, SEO consultants, etc. Jan 09, 2023 08:37PM. I was at a long red light and she dropped from 360ish to 300ish in a couple minutes. The Yamaha QT50 or Yamahopper is a noped (moped style frame architecture but lacking pedals) produced by Yamaha from the late 70s to the late 80s. 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. The immediate goal is to break 40 and then shoot for 45 mph. Ill be interested to see the difference in head temps as compared to stock head. The engine being slightly under 50cc, it was legal in some states to operate this diminutive motorcycle without a drivers licence thereby making the QT50 appealing to teanagers. New cylinder head. When you do successfully extract them, replace them with new bolts of the correct size. You can gain a little acceleration back by installing stiffer clutch springs. 10. Universal Rubber Sleeve by Motion Pro. What should you pay for (or sell) a Honda Express? YES! Due to factors beyond the control of the content producer of this website, it cannot guarantee against unauthorized modifications of the information provided or the improper use of the information provided. If you lose the oil pump, you also lose some of that snap-back tension. Air filter missing subtract $25-35. Ill make videos of each top speed run and post them here. Your bike will be almost chain-saw loud after this mod and you'll lose lots of low-end (0 to 15mph) acceleration as the engine's powerband is shifted up to the mid-high RPM range. If you are eventually planning on a bigger top end, go with the VM18. Top speed approximately 30 mph 6 volt electrics (runs with or without battery) Quick ride video Walk around video. Like I said, the stock exhaust is very restrictive and it probably has carbon build-up. Ill test it on the urban and if it helps then Ill do the same to the qt cylinder. Next, hold a finger over the spark plug hole and have a friend kick start the bike. This motorcycle, scooter or moped-related article is a stub. If it passes all the tests above, is in mint condition, and has title, I wouldnt pay more than $650. 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. It appears to have a retarding curve as well." I just bought an MLM peoples sidebleed pipe for my QT50/MJ50. Popular modifications include: Yamaha YT60 cylinder, piston and rings. Qt50s will sell for less in the fall and winter. How far do you really want to dig into it because you will only find more problems to fix. 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. Yamaha gave the QT50 a main jet that was too rich and an air filter that was too restrictive. -DO NOT CONTACT ME. Puch head arrives Monday. If your bike was owned by a kid in the past, your back tire may even be bald. 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. When it did get heat soaked, it snuck up to 394F and I had to ease off quite a bit. That is just not going to work well. Yamaha set these peds up to run rich with a stock main jet of 70 in the Mikuni carburetor. You need to take extreme care when your remove the original exhaust bolts from the old exhaust at the base of the cylinder. It is considered a motorcycle by most states. The last mod that I'd suggest is to take your cylinder off and have someone mildly raise/enlarge the exhaust/intake ports. Another culprit in QT50 excessive four stroking is the oil pump. Headlight doesnt work subtract $45; 4. The QT50 does not have a governor or a rev limiter. Sellers like to advertise their bikes as ran when last parked or just needs a carb clean or just needs tune-up. Anything goes - only rule is keep the 49cc engine. I had a spare ignition cylinder without a key that someone had given to me with a hopper that I had purchased. The Tri-Zinger has a 60cc version of this engine and the cylinder can be installed on the QT50. 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. Some have installed the HPI CDI mini rotor ignition system for yamaha QT50. Again, a performance exhaust will call for a larger main jet in the carburetor. Due to factors beyond the control of the content producer of this website, it cannot guarantee against unauthorized modifications of the information provided or the improper use of the information provided. This is my yamaha qt-50, its a 49.9cc scooter with a top speed of 32mph. 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. In sunshine red with some fresh updates. A Q-tip cut in half and then placed in your drill is another handy tool for cleaning the seat. I had this problem and it caused me to tear my hair out because I kept chasing the too little gas theory. Youd seize before you got to 40. I can tell because take offs from a stop suffer but you feel it really kick in when you get up to speed. Be mindful of not completely eliminating all four stroking. Adjust the oil injection pump; It has a 15.15 SHA clone carb and currently running a 75 main jet. Maybe sooner if you want to be more cautious. The engine doesnt need the extra fuel because its under no load or a very small load. This is the trade off for more top speed. The engine is smooth running, reliable, and long lived when proper maintenance is observed. In stock configuration, the QT50 will hit about 29-30 mph. 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. Trail Tech offers a 14mm gauge for $39 or so. This top-grade product is expertly made in compliance with stringent industry standards to offer a fusion of a well-balanced design and high level of craftsmanship. Whats the trade off? Once it gets on the pipe though, hang on! I'll make videos of each top speed run and post them here. The K&N RC-2540 Universal Clamp-On Air Filter is a good but expensive choice. 9. 6. Had a high temp of 387F and I wasnt even pushing it hard. This cut down on the brake bill dramatically. Due to factors beyond the control of the content producer of this website, it cannot guarantee against unauthorized modifications of the information provided or the improper use of the information provided. All this is necessary to avoid seizing your piston as the performance exhaust will have the effect of leaning out your fuel/air mixture. Focus on the system as a whole. Subscribe to: Posts (Atom) The 50 in the name is derived from the 50cc engine displacement. #29-3208 | Yamaha QT50 (1979-1987) Front Brake Shoes Pk/2 Diameter: 79.3mm Width: 17mm OEM Ref # 27V-W2535-00 USD$ 5 .90 Listed Models Add to Cart Float Needle #48-1558 | Yamaha QT50 (1979-1985) Float Needle High Quality - Made In Japan OEM Ref # 3L5-14190-01 SALE: USD$ 12.00 (USD$ 19 .95) Add to Cart Universal Glas-Pak Insert #009-0317 Stock Configuration and Basic Performance Upgrades, https://www.mopedarmy.com/w/index.php?title=QT50_performance&oldid=24781. Tell because take offs from a 102.5 jet to an 87 and finally to an main! This modification here at the bottom of this engine and the Honda Express,. Once it gets on the pipe though, hang on problem and it has. Mod that i 'd suggest is to break 40 and then shoot 45... The carburetor four stroking is bad stroking is bad carb clean or needs... 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yamaha qt50 top speed