Anyone w/ the BK mod or Honda diaphram?

[lost coyote]

Is there anyone that has done either of these mods and noticed a compromise in mid to full throttle? I haven't done any mods to the carb or accelerator pump yet, but the bog has to go. I just don't want to lose anything I already have to get rid of it. ?

[raven-9]

https://www.thumpertalk.com/forum/showthread.php?t=371159&highlight=honda+diaphram

https://www.thumpertalk.com/forum/showthread.php?t=377190&highlight=honda+diaphram

[Chas_M]

AP mods will have little or no effect on mid to full throttle operation.

[821]

I did the honda diaphram + powernow + JD kit on my old 05 450sx and it helped (IMO). The bike started easier and had more low-mid. The bog was gone as well. At first I wondered what all the 450 hype was, since it was my first. After the mods I became a believer.

[rbsdsu]

Diaphram in itself is a god send!!! Bog is gone!

[Peerless]

My carb has all the mods and I dont think it will ever run right. I'm just not impressed. This weekend I'll be testing it again with different settings and if it isn't like I want it, I'm going to trade it in.

[821]

Peerless, Have you dialed in the fuel screw?

[dkwok]

jus did the bk mod,

very reponsive throttle thruout,

thanks to the gurus here & over the other forom,

?

[lost coyote]

I bought the Boysen cover and was completely disappointed, I guess since I already have the Boysen I will use it in conjunction with the Honda diaphram. I was just skeptic on compromising any other performance with this modification.

[Peerless]

Have I dialed the fuel screw???? I've had this bike apart 12 times in the first month. It's ****ing junk.

[lost coyote]

Have I dialed the fuel screw???? I've had this bike apart 12 times in the first month. It's ****ing junk.

Sounds like you have a case of fingeritus. Take it to your dealer and let them dial it in. If you dont know what your doing then you can do more damage than good.

[trailrider77]

After much trial and error with many jettings kits and combos on my 05 KTM400exc, I've finally solved my bog problem that results in:

- No Bog

- I can put bike on stand idling in neutral, hand off throttle and then place my hand on the throttle and whack it full throttle as fast as possible - result is that there is no bog and it revs to the moon.

- Same results when riding the bike

- Bike pulls very hard all the way through the power range

Here's the "majic" configuration that finally worked for me:

Stock KTM float Bowl

Honda diaphragm

KTM SX needle #4

185 main

FS 1 turn out

42 pilot

O-Ring on acc. pump

Timing screw on carb (right side): adjusted out until there is only 1 thread showing (this was the key) (that means the gap is closer than .10).

KEY --> When I adjusted the timing screw on the carb so that there is a .10 gap (2-3 threads showing) the bike ran horrible.

KEY --> When I adjusted the timing screw on the carb so that only 1 thread is showing (less than .10 gap) the bike ran like a champ w/ no bog.

Adjusting the timing screw this way results in a very short but strong squirt. This was the final step that made a huge difference in how the bike ran.

Give it a try.

[cipri7]

Just try the HT Racing vane in the head (post carburetor) and needle up one notch. Stock jetting, mine runs great with no bog. You can call HT and talk directly with them... very helpful and they understand the KTM RFS really well. They advised me that starting with all the jetting and other carb mods addressed the symptoms, not the problem.

This was easy, about $75 and full satisfaction guarantee. Note that this is not the same thing as the Power Now solution. Has more to do with correcting the volume of the intake for the stock carb size and exhaust.

[lost coyote]

I bought the Boysen cover and was completely disappointed, I guess since I already have the Boysen I will use it in conjunction with the Honda diaphram. I was just skeptic on compromising any other performance with this modification.

Well I had the dealer do the mod and dial it in and it works great. Still not like the Honda. You can crack the throttle on my buddies Honda's and it just revs. This mod is about 95 percent better and it will keep me from whining about it, but still not like the Honda's.

[Peerless]

I finally solved my 450's jetting problems. I traded it in for a new 250 XCF!!!!!! What a nice piece. This bike rocks with stock jetting!!!! Wow, what a concept.