I've just put in new plugs and an aftermarket airfilter
The bike is now running rough, ok at low revs then starts to choke like its not getting fuel.
I was told that it may need rejetting to suit the new airfilter.
I was also told that it should be fine, actually I've been told all sorts of stuff!
It was running fine before hand.
I'll probably try the old (genuine) airfilter to see if that is the problem but if anyone has any tips I'd greatly appreciate it.
Bike is a 1999 cbr900, filter brand is pipercross.
Cheers

 

Hey there, welcome to the forum.

Yeah you have to re-Jet your carbs as they will run too lean now as they are getting more air than they are used to. I dont know about pipercross filters but the same rule goes for all aftermarket filters. They allow the engine to breathe more freely and improve response time and torque. I have Foam Filters on my baby and I had to reJet/adjust my air-fuel mixture as the carbs are getting more air and less fuel. Dont leave it like that in the hope of keeping fuel economy!! Too little fuel causes your bike to run very hot and do more damage than good to your plugs, cylinders and rings.

 

Thanks for the info.
I think I'll replace the new aftermarket filter with a standardOEM one.
It'll probably be a fair bit cheaper than getting it re jetted, then dyno'dfor the sake of a couple of extra horsepower.
Thanks for your help

 

Ok cool, but I think you misunderstood, or maybe it was a poor choice of words. You dont have to get a whole Jet Kit, what I meant to explain is that you just have to tweak your pilot screws to set it to the correct air fuel mixture. Yeah thats exactly what the dudes do at a Dyno Shop but you can do it yourself but if you are unsure then rather let the Dyno guys do it. You will be amazed at the difference. This is only a one time things and you will reap the benefits of the torque gain. You should expect a 5% power gain just by slapping that puppy on. That means you are talking about the difference from 125hp to 131hp, with no modifications!! Only tweaks!!

Anyways its still up to you. Cheers

 

Thanks again, I'll definately give it a go.
I'll let you know how it goes

 

So a filter mod would require a tune?