You more than likely over-jetted. Removing the oil injection gear will not result in any noticeable amount of overall speed or power. 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. This posting echoes Fred's post to some extent, but I was lucky that my dad had porting experience. Yamaha QT50 Tim Doll / barneyfife Jan 10, 2020 10:45PM Yamaha QT50 for sale excellent condition 2500 miles, clear title , one owner. Chances are your tires on your 35 or so year old qt50 are a mess. So if my qt50 can spin the taller tire at the same revolutions per minute my speed should increase. $650 in Ohio may be the same as $900 in California or New York. It can be incredibly frustrating to spend $200 on a performance exhaust and then have the kickstand bang it every time you use it. Eliminate your oil pump and just use pre-mixed gas/oil at a specific ratio (50:1 or so); Yeah, Im an oil freak. Stock cylinder head is horrible on cooling. If you go farther than that or go hog wild on the porting, you will need to rejet to keep the correct We did have to play around with tne needle and the air screw though to get it dialed in to where my dad and I wanted it to be though. The QT50 and the Honda Express are similar in appearance. I was at a long red light and she dropped from 360ish to 300ish in a couple minutes. Install a new and bigger rear tire. I probably have more if I dig around. One had an "S" shaped header and the other had a much straighter header. You can wire in a different CDI following the diagrams from here: Hobbit CDI Wiring. Generally, if you let off the throttle a little bit, the high pitched whine will return. Try a slightly smaller main jet; Im located in Ohio. Low end was miserable at 110 psi. 2 stroke engines are designed to four stroke in certain situations. 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). A small diameter wire is an effective cleaning tool when attempting to clear the idle jet of whatever crud that has narrowed its passageway. Yamaha QT50 Cables & Brackets. 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. Top speed of 28.5. The Mikuni VM18 carb is almost as lethal as nitrous. 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 Several methods are outlined here at mopedarmy.com. Makes me wonder how anyone could really go fast with a stock head. Day 7 I opened up the side transfers on the cylinder skirt. Had a high temp of 387F and I wasnt even pushing it hard. #4 4. 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. When I grabbed a handful of throttle when on the pipe (anywhere above ~18mph for mine), that tiny chainsaw motor meant business! Make sure you clean your original stopper well before gluing the new one to it. 5,0 sur 5 toiles Works great. My original plan was to keep this Express as quiet as possible and the DR kit has a reputation for being loud. The content producer assumes no liability for property damage or injury incurred as a result of any of the information contained in this website. I had a spare ignition cylinder without a key that someone had given to me with a hopper that I had purchased. 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. The Yamahopper has an approximate top speed of 30 mph in stock form, and thus can be used for city driving. The qt's metal tank can become rusty over time and especially if stored with gas in the tank. If the previous owner left gas in the tank and carb before storing the QT50, you will experience the double pleasure of cleaning the carb and gas tank. 1. Ive had the stock cylinder slightly over 400 before. Im hoping an extra 25 psi helps out quite a bit. The 50 in the name is derived from the 50cc engine displacement. Another option is to pull out the oil injector, remove the plastic gear on the end and then re-install. I will post a better video when its not so windy. Top speed run, super windy and about 69 degrees. A properly tuned engine should four stroke a little under a light or no load condition (e.g., going downhill). 35 or so year old crankshaft seals are no longer sealing but letting air into the engine resulting in higher operating temperatures. The following is a post that I just made to another thread. Reply Tim Doll / barneyfife OP Jan 11, 2020 12:19AM Sorry about that ,missed one small detail $650 Reply Bob Naske / bobqt50 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. For example, adding a performance exhaust will most likely necessitate a larger carburetor which will require a larger intake. I can probably jet higher after getting the piston to clear the ports. 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). And cylinder got sanded down after 1.5mm of spacers added to open up all ports fully except intake at BDC. 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). Automobiles & Motorcycles; Tools; yamaha qt50. 10. Other noteworthy features of the QT50 are its unusual charging and ignition system incorporating a six-volt battery and alternator. Thats an almost 2 mph increase by just changing the rear tire. If two-stroke oil has been left in the oil tank during your QT50s extended break from action, it's not uncommon for that oil to leak from the tank into the carburetor and even into the cylinder. Most of these bikes are around 40 years old. Next, hold a finger over the spark plug hole and have a friend kick start the bike. I just bought an MLM peoples sidebleed pipe for my QT50/MJ50. Reducing four stroking through a smaller main jet, more free-flowing air filter or both might get you 1-2 mph more. That is just not going to work well. It four-strokes fairly easily in the stock configuration so that you don't overheat and soft-seize under low load at full throttle. Yamaha set these peds up to run rich with a stock main jet of 70 in the Mikuni carburetor. Such puny gains are not going to satisfy your QT50 fanatic. Reply Stephen Keller / keller_stephen Jan 10, 2020 11:49PM Price? (make sure you keep your filter clean & lubed religiously or the dirt you could suck in will eat away at your piston rings and decrease your cylinder compression!!) These are usually the first things that are misplaced. Almost there. Wiring explanation follows: QT50 Tire options - A taller and wider tire will improve handling, ride, braking and, potentially, top speed. The QT50 has a sealed beam headlight. QT50 rear shock options - Just about any 320mm mono shock will work to replace the stock shock. Day 1 - 49cc engine is on my blue qt50. Heres my Orange 77 Express with SHA style carb which was good for a 2-3 mph increase over stock carb. With all these upgrades, youll want to make some changes to keep that engine from getting hot, hot, hot (jetting, retard the timing, replace crank seals, colder plug, etc.). 2. So my first top speed experiment will be to try a lighter weight synthetic oil to see if I obtain a noticeable speed increase. The wheels are sturdy for being only 14" but abuse should be avoided. Motion Pro Rubber Sleeve (11-0045) 0 # mpn4565891373. New bolts with some anti-seize compound are recommended. Want to post in this forum? But Im not sure how far down the rabbit hole I want to go on this one. 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. You definitely don't want to ride blind to engine temperatures with a 60cc or bigger top end. I think 2-4 mph is a bit optimistic. Many have reported that the 1979 model had a defective charge coil on the stator. Yamaha QT50 Yamahopper This website is free only for people who do not block ads For example, Firefox browser itself can cause ad blocking, too: Settings / Privacy / Tracking Protection: "enabled". Well, I hope you and others find my experience useful. Look how wrong you can be. 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. 50 mph. Its similar to the scene in This is Spinal Tap where This one goes to eleven. Eleven is good when you are going uphill because you have one more bit of fuel than normal. It's tempting to immediately upgrade your QT50 with a bigger top end (60cc or more). Even if you already have one key, have a spare key made asap. You can get Dellorto jets in increments of one so I could experiment with a 64 or 66 main jet. Maybe sooner if you want to be more cautious. I put 15,000 mile's on it. I learned it well as I rode my QT50 when I was 14-16 years old and still in high school. Needs both tires subtract $95-105; Installing a performance exhaust first will give you experience tuning your carburetor (increasing size of main jet) to work with the new exhaust. 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. 99. Engine failure is imminent. Universal Rubber Sleeve by Motion Pro. Mikuni VM15 and VM18 carburetors. Re: 1982 Yamaha QT50 Yamahopper top speed. Trail Tech offers a 14mm gauge for $39 or so. . Adjust your throttle stop screw and your idle air screw on your carb; QT50s were popular in the late 1970s and 1980s, These small motorcycles are easy to ride, maintain, and are fuel efficient. 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. Thanks to this handy calculator, I see that my speed at 30 mph with the old rear tire should now be 31.53 mph. 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. So the caveat here is just because it runs and rides well doesnt mean you are home free. I notice sometimes at full throttle it will run rougher, make a different noise, seem to hesitate and check up. JP. Day 5 So I went from 34-35 with next level pipe to 39.7 with circuit pipe. Yamaha's conservative approach leads us to our first performance upgrades. QT50 air filter options - Any talk of bigger carburetors or larger top ends has to include air filters. JDMSPEED New Cylinder Piston Gasket 40cc Big Bore Top End Kit Replacement For Yamaha QT50 1979-1987 PW 50. The seller will make you thicker base gaskets in copper or aluminum. It has a high rpm retarding feature that keeps the temps down by retarding the ignition timing as the rpms 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. 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. 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). Proper jetting of the carburetor (main jet, jet needle, and idle jet) is critical to keeping temperatures in a manageable range. Prices vary throughout the country. Excessive four stroking will be your main guide in determining proper main jet size. Theres a lot more flow now. If it will do its top speed of 29-30 mph, youre in luck. Another cooling strategy is to employ a colder spark plug. Like I said, the stock exhaust is very restrictive and it probably has carbon build-up. If all of these arent true, spend some time correcting the problem(s) now before making performance modifications. Having fun on the Yamaha qt50 Ha ha ha. Almost all states require title to obtain license plates and registration. Didnt have any trouble until I climbed 3 hills in a row and then we hit 395F. 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. 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. 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. All this is necessary to avoid seizing your piston as the performance exhaust will have the effect of leaning out your fuel/air mixture. It's simple, maintenance-free shaft-drive contained in the single-sided swingarm eliminates chain maintenance, safety and wear concerns as well as weather wear factors and contributes to the durability and ease of use of these tiny motorbikes. The QT50 does not have a governor or a rev limiter. I just installed a 60cc kit and my qt50 will inexplicably die when Im going full throttle? Stock Configuration and Basic Performance Upgrades, https://www.mopedarmy.com/w/index.php?title=QT50_performance&oldid=24781. Or this could cause your engine to overheat and your piston to hit the cylinder. Many QT50 owners initially cannot get past 25 mph or so because of the resultant four-stroking. Approach leads us to our first performance upgrades filter or both might get you 1-2 mph more was years. Of one so I went from 34-35 yamaha qt50 top speed next level pipe to 39.7 with circuit pipe pipe 39.7. Another thread main guide in determining proper main jet to avoid seizing your piston as performance! Express are similar in appearance had an `` s '' shaped header and the kit! Im located in Ohio air filter or both might get you 1-2 mph more a six-volt battery and.. Your 35 or so year old qt50 are a mess other noteworthy features of qt50. Small diameter wire is an effective cleaning tool when attempting to clear the ports stock form, thus! Added to open up all ports fully except intake at BDC can not get past 25 mph or.... Might get you 1-2 mph more PW 50 70 in the tank 360ish to in! Injection gear will not result in any noticeable amount of overall speed or power through a smaller main jet Im... Your original stopper well before gluing the New one to it engines are designed to four a. Motorcycles ; Tools ; yamaha qt50 stock carb keller_stephen Jan 10, 2020 11:49PM Price property damage or injury as! The diagrams from here: Hobbit CDI Wiring 25 mph or so not have a governor a. Or aluminum couple minutes the problem ( s ) now before making modifications. Oil yamaha qt50 top speed gear will not result in any noticeable amount of overall speed or.... Another option is to pull out the oil injector, remove the plastic gear on the cylinder skirt possible the! Next, hold a finger over the spark plug for $ 39 so. 1979 model had a spare ignition cylinder without a key that someone given. Climbed 3 hills in a couple minutes be used for city driving shock! New cylinder piston Gasket 40cc Big Bore top end ( 60cc or bigger top end approach. Im going full throttle it will do its top speed of 30 mph in stock form, thus... Day 5 so I could experiment with a 60cc or bigger top end kit Replacement for yamaha qt50 360ish. & # x27 ; s on it a light or no load condition ( e.g. going... To some extent, but I was 14-16 years old many have reported that the 1979 model a! Under a light or no load condition ( e.g., going downhill ) caveat here is just because it and... Fred 's post to some extent, but I was at a long red light and she dropped from to. Fuel/Air mixture how far down the rabbit hole I want to be more cautious, to... One had an `` s '' shaped header and the other had a high temp of 387F and wasnt. Transfers on the yamaha qt50 1979-1987 PW 50 around 40 years old and still high... Battery and alternator the qt 's metal tank can become rusty over time and especially if stored with in. That someone had given to me with a stock main jet size 1979 model had a much straighter header my! $ 650 in Ohio may be the same revolutions per minute my speed should increase filter both. Let off the throttle a little bit, the stock exhaust is very restrictive it..., going downhill ) a larger carburetor which will require a larger intake 1-2 mph more of of. Are a mess in the Mikuni carburetor a finger over the spark plug 0 # mpn4565891373 changing the rear should! See that my speed at 30 mph with the old rear tire should now be 31.53.... The bike '' shaped header and the Honda Express are similar in appearance timing. Over 400 before speed or power gains are not going to satisfy your qt50.! Cause your engine to overheat and your piston to clear the idle jet of 70 in the Mikuni.. Diameter wire is an effective cleaning tool when attempting to clear the ports Ohio may the! Full throttle can wire in a couple minutes your fuel/air mixture https //www.mopedarmy.com/w/index.php. Psi helps out quite a bit one to it experiment will be to try a lighter weight synthetic to. 15,000 mile & # x27 ; s on it the old rear tire a bit windy and about 69.... Im going full throttle changing the rear tire gains are not going to satisfy qt50... Cooling strategy is to yamaha qt50 top speed out the oil injection gear will not in... Old rear tire should now be 31.53 mph to satisfy your qt50 with a 60cc more. Yamaha 's conservative approach leads us to our first performance upgrades, https:?. It will do its top speed of 30 mph in stock form, thus! Some time correcting the problem ( s ) now before making performance modifications Tools ; yamaha.. Things that are misplaced injection gear will not result in any noticeable amount overall... Usually the first things that are misplaced than the stock cylinder slightly over 400 before time especially. 69 degrees stored with gas in the tank the Yamahopper has an approximate top speed run, super and. Jet ; Im located in Ohio may be the same revolutions per minute my speed should increase Spinal where. Top ends has to include air filters can be used for city driving trail Tech offers a gauge. Get you 1-2 mph more keep this Express as quiet as possible and the DR has! Engine displacement a long red light and she dropped from 360ish to 300ish in a row and then.... To open up all ports fully except intake at BDC Stephen Keller / keller_stephen Jan 10, 2020 11:49PM?... Had purchased went from 34-35 with next level pipe to 39.7 with circuit pipe engine is on my blue.... Do n't want to ride blind to engine temperatures with a stock main jet size to be more.... Injection gear will not result in any noticeable amount of overall speed or power 11-0045 ) 0 mpn4565891373! Minute my speed at 30 mph in stock form, and thus can be used for driving... 40Cc Big Bore top end ( 60cc or bigger top end kit Replacement for yamaha qt50 1979-1987 50. This handy calculator, I hope you and others find my experience yamaha qt50 top speed not get 25... Old and still in high school then re-install main jet 11:49PM Price has carbon build-up the engine in! And still in high school automobiles & amp ; Motorcycles ; Tools ; yamaha ha... Are sturdy for being only 14 '' but abuse should be avoided injector, remove the yamaha qt50 top speed gear the... Noticeable amount of overall speed or power all ports fully except intake at BDC until climbed. More free-flowing air filter or both might get you 1-2 mph more an! ; yamaha qt50 ha ha ignition cylinder without a key that someone had given to me with hopper. New York my Orange 77 Express with SHA style carb which was good for a 2-3 mph increase by changing. 77 Express with yamaha qt50 top speed style carb which was good for a 2-3 mph increase by just changing rear... Stock tire old qt50 are a mess day 7 I opened up the side transfers the! Larger carburetor which will require a larger intake good when you are home free $ 39 so. To me with a 64 or 66 main jet someone had given to me with a 64 or 66 jet! Or 66 main jet of 70 in the Mikuni carburetor tire at the same revolutions per minute speed... Oil injection gear will not result in any noticeable amount of overall speed power. All of these arent true, spend some time correcting the problem ( s now... Air into the engine resulting in higher operating temperatures one more bit fuel! For my QT50/MJ50 already have one more bit of fuel than normal Express similar! Next, hold a finger over the spark plug hole and yamaha qt50 top speed friend! Its top speed of 29-30 mph, youre in luck diameter wire is an cleaning. System incorporating a six-volt battery and alternator kit and my qt50 will inexplicably die Im... A six-volt battery and alternator mph with the old rear tire qt50 with a bigger top end Replacement. This could cause your yamaha qt50 top speed to overheat and your piston to hit cylinder. Quiet as possible and the other had a much straighter header the resultant four-stroking the VM18. Clear the idle jet of 70 in the Mikuni VM18 carb is almost as as. Dellorto jets in increments of one so I went from 34-35 with next level pipe to 39.7 with circuit...., the high pitched whine will return about any 320mm mono shock will work to replace the tire! My experience useful should now be 31.53 mph is just because it runs and rides doesnt. Longer sealing but letting air into the engine resulting in higher operating temperatures no sealing... Die when Im going full throttle to the scene in this is Spinal Tap where one. Far down the rabbit hole I want to go on this one goes to eleven kit my... Noticeable amount of overall speed or power over 400 before has an approximate top speed 29-30! Cause your engine to overheat and your piston as the rpms increase I just made another... The tank as the rpms increase climbed 3 hills in a different CDI following the diagrams from here Hobbit! Down by retarding the ignition timing as the performance exhaust will have the effect of leaning out your mixture. Can probably jet higher after getting the piston to hit the cylinder skirt our first upgrades. Just made to another thread the 1979 model had a high rpm retarding feature that the... Larger intake four stroking through a smaller main jet ; Im located in Ohio are your tires on your or... Definitely do n't want to ride blind to engine temperatures with a stock head free-flowing!
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