Motorcycle Repair: Virago 535 power loss, virago 535, needle valves

Question
Hi Chris,
I have a '94 Virago 535. About a week ago I noticed a major loss in power. Basically accelleration is fine up to about 1/2 throttle but then I get no further speed. This happens in all gears. In neutral the revs seem to increase throughout the throttle range. I have checked the throttle cable - no problem there, I have also removed and cleaned the carbs - again all seems normal. Compression is normal in both cylinders. What next?
Yours in hope, Colm.

Answer
Hi Colm.
 When you cleaned the carbs, did you check the position of the needle valves to see if they had come loose or slipped?

 Also the Virago, like all Yamaha's, is susceptible to airflow affected performance problems.  Check the air filter.  Is it due or overdue for replacement?

 You may want to check the synch on the carbs as well.  That will affect the performance by changing the timing.  The Virago has self-correcting timing when you synch the carbs.

 Are the valves due or overdue for adjustment?  You may want to check that as well.

Let me know what you find.
Good luck.
FALCON