Yamaha TTR inconsistent power delivery, what’s wrong?

by admin on March 29, 2012

Question by LaoWaiSuomi: Yamaha TTR inconsistent power delivery, what’s wrong?
I have a ’99 Yamaha TTR Raid here in China. I am living at a high elevation, and I just shipped the bike to a buddy at sea level. Since he got the bike, he has changed the fuel filter, oil and cleaned the air filter, but he says it is constantly backfiring, and stalls out on idle at times. Also, when cruising, the bike will get inconsistent with power delivery (on and off in small surges) Any help? Thanks!

Best answer:

Answer by Firestormer
The bike is running too lean due to being tuned to run at high altitude. Much the same as a pilot leans out an engine in a light plane.

Your friend will have to adjust the air/mixture screw and possibly increase the main jet size.

What do you think? Answer below!

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