The wires from your QT motor are: https://www.mopedarmy.com/w/index.php?title=Yamaha_QT50&oldid=27436. 3. 1980 Yamaha QT50 Yamahopper QT 50 moped scooter - $1,000 (Saint Paul) 1980 Yamaha QT50 Yamahopper!! Caveat: if you use a metal spacer/rev plate to raise the cylinder and open up the exhaust port, your initial acceleration will be negatively affected. Or your crankshaft seals are bad and need replaced. Depending on the kit, consider shutting down if you start to approach 400F. Of course, this would retard the timing at all rpms and may not be ideal. Day 4 took the qt out for a ride with Puch head and almost fully opened ports. 9. Mine changes gears . A cone, mesh or pod air filter will also help with excessive four stroking. . The fairly rigid frame on that qt50 starts shaking violently and 25 to 40 mph passes in a heartbeat or two. 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. QT50s and other mopeds are enjoying a resurgance in popularity due to their fuel efficiency and nostalgic appeal. 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. The 50 in the name is derived from the 50cc engine displacement. Makes me wonder how anyone could really go fast with a stock head. If it is a complete mess, chances are the inside isnt much better. 1979 Yamaha qt50 speed run - YouTube AboutPressCopyrightContact usCreatorsAdvertiseDevelopersTermsPrivacyPolicy & SafetyHow YouTube worksTest new features 2022 Google LLC Remplacement pour Yamaha QT50 1979-1987 ; . I notice sometimes at full throttle it will run rougher, make a different noise, seem to hesitate and check up. Pull off the battery cover and check out the wiring in the back as well. Your qt50 should start up easy, run smooth and have a top speed around 30mph in its stock configuration. Be mindful of not completely eliminating all four stroking. a video on this modification here at the bottom of this page. 5. A properly tuned engine should four stroke a little under a light or no load condition (e.g., going downhill). My Honda Express at the time of purchase. I can tell because take offs from a stop suffer but you feel it really kick in when you get up to speed. 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. I could do longer full throttle runs. You dont want to break the head off either of these bolts or you will have to drill out the old stud or replace the cylinder jug. The oil pump is reputed to add excessive amounts of two stroke oil to the fuel. Youll need to increase the size of the main jet when you do this. Had a high temp of 387F and I wasnt even pushing it hard. Right and left side crankshaft seals can be found on ebay or treatland.tv. A popular choice is the IRC NR-77 moped tire: 14 x 70/90. So the caveat here is just because it runs and rides well doesnt mean you are home free. 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 you increase top speed, make sure to upgrade your brakes with new pads, new cables, lube old cables, etc. Install a new and bigger rear tire. 2. What should I look for? I consider myself fortunate as my dad was very knowledgeable about how 2-stroke engines run and what you need to do to make them "breathe" better. Consider it a $39 insurance policy. 3.8 out of 5 stars 64. Rinse and repeat several times. A combination of the above. Truth is it is getting too much gas and dying as a result. Prices vary throughout the year with the change of seasons. 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. The simplified driveshaft setup makes wheel changes easy. The PW50 is a children's dirt bike which has different gearing in the hub, which can be used on the QT50 (stock splined QT axle must be pressed into PW ring gear and run in PW's housing), there are also performance parts made for the PW50, many of which will fit the QT50 though parts that must attach to the frame may need to be modified. The Yamahopper has an approximate top speed of 30 mph in stock form, and thus can be used for city driving. If it does not, your compression will suffer. Or fastest delivery Jan 20 - 24 . 5. The Dell'Orto SHA 15.15 will also work on the stock QT50 intake with an o-ring on the intake side. You may also choose to richen up your jet needle by moving the clip down one or more positions. It gets around 100-125 mpg, its really reliable, I use it to drive to campus, you can park it on the bike racks and. You will also want the Malossi exhaust gasket. I solved it by going from a 102.5 jet to an 87 and finally to an 85 main jet. Bent forks such that it pulls hard to one side when riding subtract $85; 2/1/16 Ok, just did a base speed test and hit 29.4 mph. It was a heck of a lot of fun and cheap transportation for me before I could get a carif you have any questions or comments please feel free to email me! Does the owner have title? 10. In 2018, MLM introduced the MLM yamaha QT50 techno EDM circuit pipe. The QT50 drive train was shared by the Tri-Zinger and PW50. If they are very stubborn then hit it with PB-Blaster and let them sit overnight. Ron Peek / yamahauler. My initial acceleration may be a bit slower with the bigger rear tire. 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. The other 2 wires are power for lights or battery. Qt50s will sell for less in the fall and winter. Buy yamaha qt50 online with fast delivery and free shipping. As above, a cheap aftermarket 6 volt flasher is easily attained. Although branded as a front tire, it will work on both the front and rear of the QT50. A Q-tip cut in half and then placed in your drill is another handy tool for cleaning the seat. I never ran into overheating problems, nor did I ever have a mechanical breakdown because I kept up on its maintenence. A bigger cylinder head would also help with cooling. Shine the light into the gas tank and determine how rusty the inside of the tank is. Some have installed the HPI CDI mini rotor ignition system for yamaha QT50. If the bike doesnt run, make sure you can push down the kick start with ease. Anything goes - only rule is keep the 49cc engine. Unfortunately, its fairly common for people to lose the key. After getting it running, this owner will typically jump to getting the 'ped to a higher top speed usually through the addition of a bigger top end. The Yamahopper has an approximate top speed of 30 mph in stock form, and thus can be used for city driving. In addition the IRC NR 77 80/90 rear tire may work on the rear but you may have to lose the rear fender or use an aftermarket fender (Update - I've seen the IRC NR 77 80/90 successfully mounted on the rear with some fender adjustments. Many mistake the low, rough growl as a result of a rev limiter residing in the CDI unit or perhaps elsewhere. I hope compression gets better as the rings seat. Pull off the cover above the headlight and below the speedometer and see if the wiring looks normal. Ive had at least two qt50s with bald back tires. QT50s were popular in the late 1970s and 1980s because of their ease of use and maintenance, extremely low gas mileage, and legality in most U.S. states among pre-driving-age teenagers. I can bump the main jet again and see if that does the trick. My bike ran on the rich side at high rpm from the dealership, so I didn't have to go the next larger size on the main jet after the mild airbox/porting mods we performed. So, in essence, it would be getting too little fuel. dead battery subtract $25; Focus on the system as a whole. Youll think your qt is not getting enough gas because it stalls. It has a 15.15 SHA clone carb and currently running a 75 main jet. Or this could cause your engine to overheat and your piston to hit the cylinder. Best jetting for VM18 on this setup seems to be 20 idle jet and 80 main jet. 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. Automobiles & Motorcycles; Tools; yamaha qt50. One leads to the oil pump and one leads to the carburetor. Install a free-flowing air filter; You should see a large circle of light through the main jet and a much smaller circle of light through the idle jet. Chances are your tires on your 35 or so year old qt50 are a mess. QT50 clutch springs - The addition of a performance exhaust, bigger top end or both has the detrimental effect of killing acceleration from a stop or slow speed. 1. Jemco exhaust, etc. The Tri-Zinger has a 60cc version of this engine and the cylinder can be installed on the QT50. Controlling the heat produced by a bigger top end and/or a performance exhaust is a common issue with QT50s. It also leads to using a key other than the Yamahopper one. Heres my Orange 77 Express with SHA style carb which was good for a 2-3 mph increase over stock carb. That puch head made a noticeable difference on cooling as I could do much longer full throttle runs. Low end was miserable at 110 psi. Maybe sooner if you want to be more cautious. Worth it? This cut down on the brake bill dramatically. Try a slightly smaller main jet; 10. Adjust the oil injection pump; 2/8/19 Ok, I gave up on the DR kit/stock exhaust combo. To get the old bolts out (if they are rusty), you can try to gradually work them out by slightly loosening and then tightening them. Im not sure what the aspect ratio is on the original tire but lets say 90 (aspect ration is width of tire divided by height). Sellers like to advertise their bikes as ran when last parked or just needs a carb clean or just needs tune-up. That extra bit of fuel that causes some four stroking is required by the engine when it is under greater loads like climbing hills, running into a strong wind, etc. I ordered a puch 40mm head. Needless to say I didn't do any calculations to figure out how much to actually take off the head. What should you pay for (or sell) a Honda Express? The bigger rear tire is heavier and your qt50 in stock form may not be able to spin it at the same rpms as the original tire. Be nice to her. Ride, handling, braking and, to a small extent, top speed can be improved with them. I also read on mopedarmy.com (concerning the Suzuki FA50) that if you went from 20W-40 conventional oil to 10W-30 synthetic oil, you would obtain a 2-4 mph top speed increase. The straighter header will perform better; however, a used QT50 exhaust cannot be had for pennies on ebay and your money may be better spent on a performance exhaust. I replaced both crank shaft bearing seals prior to installing the kit. It also seems to help if you reconnect the common ground shared between the charge coil and the light coil. But, I was also riding with a full open throttle. 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. Reply Tim Doll / barneyfife OP Jan 11, 2020 12:19AM Sorry about that ,missed one small detail $650 Reply Bob Naske / bobqt50 They just need to make the cylinder "breathe" better at mid/high RPM. 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. The engine is smooth running, reliable, and long lived when proper maintenance is observed. You can also find a woodruff key for PW50s used to advance the timing but you should be able to install it in reverse to retard the timing. . What you are experiencing is a phenomenon known as four-stroking. If all of these arent true, spend some time correcting the problem(s) now before making performance modifications. Im going to look at changing the jetting next. 1. 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. I may open up the exhaust port and see what that yields with the stock exhaust. Many attribute this wall to some sort of rev limiter. Or adding a bigger top end will require other modifications in order to achieve the potential of the new top end. Other cooling methods include running a thicker head gasket (or more than one head gasket) to reduce compression (you can also reduce compression by increasing cylinder head chamber size) and running a Jog cdi with a curve that allegedly retards timing at higher rpms. Day 7 I opened up the side transfers on the cylinder skirt. Spring is always the hot season for noped and moped sales. 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. Half the package or less is plenty. Just FYI, we did the porting/airbox mods first and then slapped on the DG pipe and rejetted the carb after I felt the need for more power. Such puny gains are not going to satisfy your QT50 fanatic. 7. My top speed now is somewhere around 28 mph. Overheating and piston seizure are traps for the unwary. 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. Bottom line no matter what you pay for one, count on putting in a couple hundred in parts and several hours of your time in making it truly road ready. 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. I probably have more if I dig around. Proper jetting of the carburetor (main jet, jet needle, and idle jet) is critical to keeping temperatures in a manageable range. 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. #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 Day 2 bumped up the main jet slightly to a 67.5 and it took a bit longer for the engine to get heat soaked. I talk about this above. Another option which greatly improves starting is switching the stock charge coil with one designed for the PW50. The following is a guide of some sorts of what CAN and CANNOT be used while restoring this guy It CAN use the same Shock as the QT50 It CANNOT use the QT50 crank It CANNOT use the Chappy crank It CAN use the same CDI magneto as the QT50 Chances are you still wont get a good idea of how rusty the tank is even by doing this. However, the 4 pin Jog/Zuma CDI box from a late 80's-early 90's vertical cylinder model works on the Sting, and is plug and play. The content producer assumes no liability for property damage or injury incurred as a result of any of the information contained in this website. Next step will be to change transmission oil and see if we get any gains or, worse yet, lose any speed. Manufactured. Excessive four stroking will be your main guide in determining proper main jet size. Get an aftermarket mesh air filter. 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. 8/6/2018 So I kind of lost track of this thread and thought Id pick it up again. This jailbreaks the relatively generous exhaust port (in the stock configuration, the piston partially covers a portion of the exhaust port at bottom dead center; the rev plate raises the cylinder jug and thus allows the piston to fully expose the exhaust port at bottom dead center). Stock cylinder head is horrible on cooling. A temperature gauge is your best friend and a cheap insurance policy on your quest for better performance. Ill be interested to see the difference in head temps as compared to stock head. If your bike was owned by a kid in the past, your back tire may even be bald. With all this in mind, what should you pay for a Yamaha qt50? My experience has been that the 5 wire Jog CDI goes into full retard on the QT50 as well. 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. Cone mesh air filters of the 28-29mm variety are plentiful and cheap on eBay or amazon and equally effective. 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. Re: 1982 Yamaha QT50 Yamahopper top speed. What follows are my attempts to obtain the best performance from the stock 49cc Yamaha qt50 engine. Kevlar brake pads and stiffer clutch springs! Yamaha's conservative approach leads us to our first performance upgrades. Any 28 or 29mm air filter is most likely an improvement over the stock air box (although many have resorted to drilling speed holes into the stock air box). A too lean mixture can cause serious engine damage. A small diameter wire is an effective cleaning tool when attempting to clear the idle jet of whatever crud that has narrowed its passageway. We are ready to rock as soon as the weather cooperates. However, this 5 wire box DOES NOT work for the Sting. Maybe Ill shoot for Pete Roses number. 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. Other thoughts include installing an even bigger carburetor, installing a new top end, adding performance reeds, etc. Almost all states require title to obtain license plates and registration. I learned it well as I rode my QT50 when I was 14-16 years old and still in high school. 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. 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. Of course, this makes me wonder if I can use an IRC NC 77 80/9014 tire. I cleaned up the transfers on a Honda cylinder like the pic above. If it passes all the tests above, is in mint condition, and has title, I wouldnt pay more than $650.
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yamaha qt50 top speed