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The standard noob FCR jetting questions.

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I hate making this post, as I know it's been posted about a thousand times, but I'm really on it when it comes to dialing my new FCR39 in.

I've got an '05 SM, with an
ABP header ( should be the same as the E header ),
Leovince LX3 muffler with the db killer removed,
3x3 mod, K&N filter,
And of course an FCR39 which has a stronger AP spring, equal to the o ring mod. The FCR is originally for a KTM, but I modded it to fit my DRZ.

I live very close to the sea level, and won't be riding in high altitudes unless I leave the country.

Anyhoo, I've got a 160 main jet in there, 45 pilot jet, 2 turns out, EMN needle 3rd clip, rest is stock afaik. I think the AP jet is removed though, I remember as if it was recessed in a hole.

It felt low on power up high, didn't pull as hard as it used to. I'll be swapping the 160 to a 155.


I just can't get it to idle properly. When it's warmed up after running a couple minutes with increased throttle, it runs nice and steady at 1400-ish. If I just twist the throttle it sounds like it's about to die but doesn't- it dies when cold though. It will rev just fine, but when I let go of the gas it falls to around 1700, then drops to 1400 after 2 seconds.

It needs choke to start when cold, it can start without but it stalls after a second. When it's warm I barely have to touch the starter and it jumps back to life.

Pulling the choke when warm is like hitting the off switch, it dies instantly.

When I try to dial the mixture screw, I never really find that increase in rpm I was told to dial it after. I dialed it after not stalling when twisting the throttle.

I started with a 48 idle jet, which ran fine when dialed all the way in, so I swapped it for a 45 which runs well at around 2 turns out.

Edited by v0nsild

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Hope you get it sorted mate , jeting can be a pain in the arse , mine developed a massive low throtle stutter this week put some sea foam through the tank & it appears to have sorted it

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