Hi, I have a 02 F4i and I’m having the issue where my bike doesn’t wanna go past 9 or 10 k without sounding like it’s gonna blow up. I’ve checked all hoses and fuel lines and nothing seems to be kinked. What else would it be? I run at 7k rpms going 55. That’s wild high. I did do a sprocket set change, but it shouldn’t affect it that much, it won’t even hit the power band. TIA!

 

How much did you change the sprockets by, and are you using all 6 gears?

7k RPM at 55 sounds like you're in 3rd. The standard sprockets I think are 16/46 = 2.88 ratio

 

yes, im using all 6. I can’t remember what sizes I put on, all I know is it produces more torque and less top speed. Both sprockets got changed in size. But that shouldn’t make it run at 7k and 85k on the highway.

 

Actually that’s exactly what we would expect. There’s no slip between the crank and the wheel - If you are in 6th then the only explanation is you changed the sprocket ratio. Go count the teeth.

 

yes, I changed the sprocket ratio. But this would make it so the bike never hits the power band? It barely makes it to 10k RPMS. Let alone all the way to 15 or 16.

 

is there anyway my valves could be going bad? Bike has 24,000 miles and a shorty exhaust on it.

 

I'm confused.

Will it not run past 10k in any gear?
OR
Does going 75mph make it get to 10k rpm and you don't want to run it any higher?

It won't go to 15 or 16 unless you've removed the limiter.

And we do need a count on the teeth for both sprockets. This will give final gear ratio and tell us what the top end will be as well as speed for any given RPM.

 

Everything that the guys have said is spot on.
One thing to keep in mind is that these bikes are set up in a specific way to provide an even, broad range of power across the spectrum. When we modify that setup, we change the way the bike can perform across that same spectrum.
Think of a triangle that is even across all three sides. If you take and stretch one of the points of that triangle making it longer, you now have sides that are no longer of equal length. It's still a triangle but has different properties in every way. In this conversation, changing the sprockets is changing the point of a triangle, You get better performance in one area, but you sacrifice a different area. Your triangle has changed shape.

 

Well I understand that it would change the ratios and such, but it’s acting as if there’s a kink or something to where it’s restricting how it will ride. It should have gave me torque with the sprocket set change, but it didn’t change anything really. All I’ve noticed is that it’s a hell of a lot slower. The reason I say a kinked fuel line is because I’ve had a kinked fuel line before and it acted the same exact way as now. Just coincidentally at the same time.

 

Why are you so resistant on telling us what sprockets you used? Red flag for me that you might be a troll.