My '84 QT50 stutters just as it reaches the upper end of 2nd gear. This improved somewhat after I cooked the muffler in a campfire and crispified the crud in it. I've cleaned the exhaust port with scraping tools but have not run the machine just yet because I'm doing fork work on it. If this problem persists what is to be done about it? Is this just something I have to live with ?

Re: QT50

I don't think the QT has a second gear. I also have a QT and from What i can see its only got one speed. Mine kinda shutters at full speed and will back off slightly. If i let off and back on it accelerates again to about 28 mph and then backs off and shuttersa again.. But I'm thinking a carb adjsutment might fix that. I did a slight one but have not run it yet to full throttle I only did it at idle to get it to run smooth there. As soon as i get my new air filter This week I'll let you know. My carb is totally clean and so is my muffler so i know its none of those. Is this the same "upper end" type issue you were talking about?

I'm also thiking it might be my fuel flow from the tank too. When i had another tank on it for testing i didn't have that problem, right now the fuel seems to trickle out rather than run out. Check your fuel shut of and make sure its not plugged.

Re: QT50

handymanmccoy /

Those are good ideas. I'll let you know what happens when I get the forks back on. They are bent. Do you know anybody with QT parts to sell?

Re: QT50

there are some people on ebay selling parts. I cntacted a guy that was parting out a 1980. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4545907797

That is the link to the seller. Contact him and see if he has what you need. I was going to buy the CDI and controller box from him but the 1980 doesn't have the controller. he didn't have the parts listed but gave me a price for them anyway.

Those forks are weird huh? If they ever wear out you gotta buy a whole thing. the tops are welded on the inside were the slides go. and even the rubber wipers can't be removed. Kinda sucks. I think some day I'd like to modify a set of mountain bike forks and find a used mountain bike shock for the rear. it'd have better dampening. I'l let you know how it goes once i get that filter. Don't want to run it and get dirt in a freshly cleaned up carb.

Re: QT50

One way to find out if your bike is "4-stroking" at high speed is to remove the air filter. i have a 1982 QT50 and it does the same thing unless you remove the air filter. After you remove it, they run about 30-32mph.

Re: QT50

Thats exactly what mines doing. Sorry about the 2nd gear thing. I noticed too now that the QT shifts when its going. never rode it for real until last night. I played with the carb and it didn't seem to fix much. It was about 9:30 at night when i was running it so i didn't stop much to adjust. Hopefully this weekend I'll take it to a school parking lot and do speed runs and some more slight adjsutments and see if it gets rid of it. To me it sounds like a a or rv limiter.

taking the air filter if it does work doesn't make sense cuz your engine won't last long without it. But how did you cure it? Did you continue to run without the filter or did you do some carb adjustments?


Re: QT50

i just picked up an 82 qt 50 and i need a key. it runs but the owner wouldnt part with the key (and for $20 for the bike i didnt complain) because he swore it was lucky. anyone know a way to get one? i was also wondering if anyone has done any brake work on a Yahmahopper.

Re: QT50

I've done brake work. It's easy. The pads tend to desintregrate when they sit. Also, did you get it running? It's probably blown up if he wouldn't give you the key. Keys.. I dunno, I just lost mine on the way to get it copied, and I'm looking for an entire ignition switch too.. Anybody know of one?


Any questions on brakes, just ask. I'd suggest while you're in there, change out the actual cables. The old ones tend to be weird and stretchy / breaky.

Re: QT50

Brakes are really easy. Just pull the wheels off and clean the drums out. Reinstall new brakes just as the old ones were. Put a little lube on the flat piece that pushes the calipers open.

Where did you get your braek cables from? the dealer or else where?

Re: QT50

Whenever you reassemble a drum brake on a moped or cycle, don't forget to centralize it first.

After the wheel is reinstalled, tighten the axle nuts lightly, to take up play, but not fully tight. You just want them to have a light grip on the assembly.

Then, spin the wheel fast, and grab the brake good and hard. Do this several times, and then while holding the brake firmly, tighten the axle nuts. This will help to centralize the brake shoes in the drum, and give you better brake action.

Re: QT50

thanks for all the help everybody. i need brake cables and dont even know where to start looking. the back breaks are in good shape except for the cable and i still need a key. i hot wired and it runs really well, stutters a bit at higher speeds but i dont want to run the battery down or run into electrical problems.

Re: QT50


my front brake cable broke so i called Dennis kirk they gave me a number to a company in California that makes brake cables from scratch . i sent in my old broken cable so they could copy it .it will cost around i think 30 dollars i think.

talking about brakes where can i get brake pads? my brakes squeeke when i stop.

thanks j

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