hello I'm a little lost
I have a KLX 250s EFI 2009 model
it's original except for Q4 FMF
I'm looking for more power but without changing original cyclinder
Do you know what' s the best mod presently for injection type ?
can you say me if really following mods are ok to increase power:
multilevel filter
snorkle kdx 200
iridium spark plug
thanks for your help

 

I use a Uni filter, allows it to breath a lot better. Just leave the snorkle off unless you plan on crossing rivers.
I was advised to add a piggyback fuel controller to enrichen the mixture after fitting my pipe and filter, however I found that this did not give much of a bump in power. The EFI can compensate for the stage 1 mods ( pipe and filter ) according to the EFI gurus.

I assume that you have done the clutch switch modification to get rid of the rev limiter in 4, 5 and 6th gears?

The best increase in power is going to come from the Marcellino cam mods that you will find at the beginning of this forum, under sticky posts.

Other than that I tried everything possible with my 250 as far as free mods go. They all helped a bit and made it sound better. However for all the cash I spent scratching for a few more HP, I should have gone big bore straight away. As soon as I spent 600 bucks on a 300 kit, the bike took off. If I were you, I would save for a 331 kit and a piggyback controller, like EJK or Powercommander. Then you will be laughing.
These are tried and tested by a number of EFI guys on the forum, and you can get plenty help here.
Now go and stuff some money in your piggybank and stop spending on gimmicks.

 

+1 Graham, Now go and stuff some money in your piggybank and stop spending on gimmicks.

There are a couple of threads on here that you can search for that go into way more detail.

The KLX250 with a carb can be a fun bike & make decent power with the airbox opened up, a pumper carb or a jet kit & the Marcellino cam mod. Easy enough to do & transforms the bike.

The KLX250 EFi is much harder to play with, especially when trying to get the same power the carb boys get so easily!! The EFi bike was built to comply to with the daft euro3 emission laws & as a result has the power of a fart in a tea cup!! You need a fuel controller/piggyback to burn more fuel & get a bigger bang. The stock ecu/mapping probably runs in the high 14's or even a 15 AFR out the factory, which is super lean!!! (12.5 - 13.5 is a strong air fuel ratio btw), Euro3 is a tough as any California regulations!

Basically, if a 5-10% power increase will keep you happy then do the usual mods......If a 30-35% increase in power is desired then it has to be a 331 big bore kit or buy something faster like a ktm or a Husky! (only applies if you got EFi).

 

thanks a lot for your suggestion