520EXC Jetting w/ Exhaust

endoquest

Lifetime Sponsor
Joined
Dec 4, 2000
Messages
325
Likes
0
#1
Has anyone experimented with jetting after switching to an aftermarket exhaust?. I've installed an FMF SA with the QII endcap. The only gain I've gotten out of it is the difference in weight and slightly higher overrev, which doesn't do anything on this bike. Which way should I go? lean or fat? needle or main or pilot?
I probably don't need to change anything but fiddling is one of my favorite pastimes. Bring it on!

------------------
President,ETRA.
'01 KTM520E,
'99 KTM200E,
'93 CR500R
enee,menee,minee,mo
 
Joined
Feb 25, 2001
Messages
49
Likes
0
#2
My understanding is the big KTM RFS needs more air. Drill a couple of holes (1") on your side airbox cover, buy a few of the 1" filter inserts that are specifically made for that, go up 1 or 2 on the main, and 1 or 2 richer on the needle too. When I bought my 520 the prior owner ad a big gun pipe on it, and it was too loud and had bad quality issues, so I asked him to put the stock one back on. He richened the pilot, needle and main when he had the Big Gun exhaust on it, and leaned it back towards stock some when he put the original pipe back on. I do believe the stock silencer is restrictive somewhat, but i like how quiet it is. I am suprised you did not feel much of a difference with your FMF. I have heard the regular Power Core S/A(non quiet) makes it stupid fast


------------------
01KTM520EXC
91Yam WR250 4sale
86XR350
74TM125
 

endoquest

Lifetime Sponsor
Joined
Dec 4, 2000
Messages
325
Likes
0
#3
Thanks Trail Junkie. I spend too much time in the wet to be drilling holes in the airbox. I also use the stock muffler when I have to pass a sound test. I have both endcaps for my FMF and would like to try the straight Power Core with fatter jetting. I have a desert race in two weeks that doesn't require sound test so I'll try it then. I'm tired of loud bikes though, it's not good for our sport. Cheers
BTW the FMF website says that no jetting changes are necessary for the Power Core, it does mention the holes in the airbox though, but only for the 520SX, hmmmm.

------------------
President,ETRA.
'01 KTM520E,
'99 KTM200E,
'93 CR500R
enee,menee,minee,mo

[This message has been edited by endoqwest (edited 04-15-2001).]