I have recently bought a 1990 fzr250r and have done alot of reading on this site before i decided to post this problem. I bought the bike without a CDI. I obtained a CDI and strarted the bike. My problem is the bike sputters when i pull the throttle except to a point, about 1/4 turn. At the 1/4 turn point the bike revs good but dosent cross 10k rpm.If i pull full throttle the bike revs down and Kinda coughs as though its stifiling. I have cleaned all the jets and ports in the carbs. I have adjusted the air screws to 2 and 1/2 turns as recommended. I have read all your posts on the carbs and also adjusted my float heights to recommended fuel levels. I do not have an airbox on the bike, will this cause a problem? Do you guys think it is en electronic problem. My brother has a Honda 250rr and was seeing a similar problem, it was sloved by repairing a loose wire. I really want my yamaha to run well, because in my area its like a 250 wars going on. From honda vs suzuki vs kawasaki vs yamaha. I love yamaha.
this bike HAS to have the airbox on! After I finished cleaning the carbs I started it without the box. I had to play with the throttle to get it to rev out. Once the airbox was on it would pull cleanly all the way to 18,000. Put your airbox back on.
