Yamahopper starts and runs fine for like 5 minutes

John Wattleworth /

I was wondering if anyone out there could help me? I have a 1980 or so QT50 Yamahopper. It starts every time. After letting it sit for 20 minutes or so it starts and then I can ride it for like 5 or 10 minutes just fine. Then after that I go and turn the throttle and the engine bogs down and then stalls. I have cleaned the Carb. Could the petcock be causing this problem? Thanks for all of you help!!!

Re: Yamahopper starts and runs fine for like 5 min

Leon Swarmer /

could be a clogged fuel cap vent.

leave the cap a bit loose and run it for a while

or..if you can. ..run it till it is ready to die and take the lid off. IF either of these tests makes it happy then you can clean the lid vent and ride on.

Leon

Re: Yamahopper starts and runs fine for like 5 min

John Wattleworth /

I tried that and that didn't work, but thanks. I cleaned the petcock and fuel is flowing just fine to the carb. So I really don't know what to do now. Any suggestions would be greatly appreciated.

Re: Yamahopper starts and runs fine for like 5 min

I got this problem 2 times, first time it was the carb being dirty. 2nd was : The needle that goes in the carb to block the main jet, the lock that holds it to the throttle cable came off. So when I full throttled it only air was going in and very minimal gas. The needle was crooked so it let some fuel in the engine. Thats what made it run but it always bogged. So I changed the needle and lock and now it runs fine.

Sorry for the long text.

Re: Yamahopper starts and runs fine for like 5 min

i say run it without the cap and see if it still dies. i had same prob and taking cap off when it was ready to die didn't keep it running but it WAS a tank vaccume issue.

Re: Yamahopper starts and runs fine for like 5 min

John Wattleworth /

I took the carb apart and tried to take the throttle and choke assembly apart but the choke needle was slightly bent and the choke is stuck in the on position. I haven't tried to starten out the needle yet, but I think this maybe the problem. What do you think?

Re: Yamahopper starts and runs fine for like 5 min

It may not be the problem but if I where you Id change that choke needle right away. Dont try and reuse it, get a new one.

Re: Yamahopper starts and runs fine for like 5 min

John Wattleworth /

Where can I get a new choke neddle from?? Thanks

Re: Yamahopper starts and runs fine for like 5 min

Keith Wallace /

partsfish.com carries all your yamaha and honda part needs.

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