QT 50 speed /power issue

Haven't been on this forum in a long while, but im happy to see several QT 50 articles recently. If there isn't an online club anywhere, or a specific forum, we should start one.

Anyway, to my problem:

I have a 1980 QT... and as of late it has developed a problem in that it takes VERY little to slow it down a LOT. For example, I usually ended up with around 27-30 mph top speed. Now I max at 25, and a 10 mph head wind will drop me to around 23. I can't make it up the short hill to my street anymore either (half block, at 2-3% grade)

Some history, and mods. I had a big problem last summer where it would seem to flood out randomly, and loose power all the time. I cleaned out the exhaust to the best of my ability, with a coat hanger, and pulled out a nest of small slugs. THen I cleaned the exhaust port, which was about 50% plugged. Cleaned out the carb. though it looked clan enough to eat off of. No difference at all. I installed a main jet that was one size smaller than stock, in the carb, and loosened the exhust pipe, and stuck a small washer between it and the block, and tightened it down again. it was running leaner, and faster.

Now the above problem. I installed a new spark plug, and cleaned the buit up carbon on the head., and took the crancase cover off to see if the clutch looked like it was slipping more than it needed to be.. didn't seem to be..

By the way, how does one make sure that the clutch is putting all the power it can to the road?

I have seen some posts from people that seem to know this bike well, I hope they grace me with the some help... thanks!

Re: QT 50 speed /power issue

david f martin /


Remove the cylinder completely, and clean the exhaust port inside and out (a small pocketknife works well).


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