RX-1 Trouble

[bird222]

Help.I have a 2003 Yamaha RX-1. I just installed a K&N filter kit, I also changed the main jet to a 165, and installed the Holtzman silver slide springs as recommended. Now it seems to run good sounds great but lost top end bad and plugs look lean after first 230kms tour. Feels strong on bottom end but at 100kms not nearly as strong as before and top speed 150, will adjusting jet needle help ? I think I need more fuel? Thanks

 

[yamahamaniac]

Mine is completely stock and since this year started I havn't been able to get any where near my top end as last year. I'm lucky if she goes 165km/h.

 

[BB]

Sometimes it is hard to read a 4 stroke plug . What elevation do you ride? Sounds like your main jets are way to big making your top end not right. If you run NOS at 4-6000 ft you should run 155mains if not you should run I think with past experience 145 main. I ran both stock then NOS and now I run a side mount turbo I hope this helps if any questions reply back.

 

[Ratpack]

I ran 155's in mine at 1500 feet.It always ran very well.