Acc pump adjustment on FCRMX

During my Athena conversion I discovered that the squirt time of acc pump is quite long like 2 seconds. I know I should be able to figure out how to adjust, but I though somebody here (Eddie maybe :thumbsup:) has already done that.

My carb is a FCR-MX from KTM450EXC '04. This long squirt time has not caused me any problems, carb has been great. Should I leave it alone or what?

If it aint broke...

Has it been a problem-? like he said if it aint broke.

But- depending on riding style you may not notice it. If you do notice a bog with what would be a "normal" baseline as Eddie has established. Then I would suspect the AP duration/ timing. Commonly, duration times sought after are .5 second to 1 second. Timing is important too- the squirt should just miss the slide as it moves up.

CHeck out the Jetting forum and search about AP timing, Ways to adjust are with the BK mod, diferent diaphrams, and leak jets if you have them. The Taffy Mod is for older FCRs that have an expolsed AP rod- so not for you. Adjusting the timing of the AP has less to do with bike type as does normal jetting- so its ok if the subject bike is a yamaha or a KTM. My brother has a KTM 450 and just put in a yamaha diaphram to shortan the duration. He got that information of the KTM forum. Diaphrams have different size spacers on the bottom limmiting their movement thus squirt duration.

Hope this is helpfull,


Thanks guys. I think I'll leave it alone for time being and fix it if it causes trouble.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now