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EXC 400 2005 low to mid- poor acceleration

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Friend rides this bike, but is somehow not satisfied with low to middle power rise.

Bike is stock, with deblocked silencer and has standard jets, valves are checked OK.

For instance, riding second gear, opening the throttle, bike doesn't bog, but accelerates very poor and slow, so if in need to pull the wheel up over a log, has to use clutch.

Is there any advice to repair this, probably pilot jet setup.

There is no altitude, humidity or temperature problems in the riding area.

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stock jetting is never right on a KTM, they need a different needle, also the 400 just isn't going to have the same kind of torque a 525 does, so don't have your expectation's too high. 05 year did not have a corked up silencer to begin with.

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This one was corked, euro models may be a bit diffrent.

Completely downsized with jets and silencer, due to emission regulations, but kit is included, to make bike run OK.

fo instance 148 to 175 main jet.

Know it wont get power surge as 450 or even 525, but it should at least accelerate moderately.

Need info from 400 riders, what they did to improve this.

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My 400 lofts the front wheel at will. No problem doing wheelies or lifting the front over logs anytime. I have richened up the pilot and main jet and also have shortened the squirt time with a modified diaphram. I also fixed the linkage so there is no delay when twisting the throttle.

What about gearing? Has it changed? Did the owner install a rear tire with a larger diameter ?

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Gearing std 14/50 and michelin enduro comp III 140/80/18, so no change here.

Must be the carb. Could you go exact on the jets, just to compare.

All other mods are completely clear to understand and only require buy and install.

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Must be the carb. Could you go exact on the jets, just to compare.

.

See below- I think the EMN or EMP would work great for you with a 165 168 or 162 Main depending on temps and elevation-can also get a JD kit, probably a 45 pilot- check with test by closing fuel screw and if does not stumble you need a smaller one- if is optimum idle is with fuel screw out 2.5+ turns concider a size larger:thumbsup:

Taken from the FAQ:

Here

03-06 400: These needed a 42 or 45 pilot, and as the stock needle is too lean work best with either;

JD kit, or

OBEVP needle, main jet about 155

A good aid on these is 03-05 models you can do the BK Mod or any year the Honda diaphragm and can be made a bit more responsive with an Oring on the throttle linkage (see ac pump 101)

Here

2: Sudco is the importer of Keihin parts, your on your own but for the KTM 400-525 a OCEMP with a 162 main is a pretty workable combo. Do to the step taper this combo is richer in the ½ to ¾ throttle range then the JD. If you spend a lot of time flogging in sand dunes consider this combo!

Here

Honda, you get a couple other pieces with it that you can ignore a bargain at under $20 (Honda allegedly owns Kehein so they can sell parts for less). Honda’s number is 16021-MEB-771, or

Yamaha, price is a bit higher I think close to $30 but there is some in between lengths available

part # 5JG-14940-19-00, (9mm post) would be the same as the Honda (short squirt)

part # 5JG-14940-18-00, (8mm post) a little longer squirt

part # 5JG-14940-76-00, (7.5mm post) a little longer yet

part # 5JG-14940-17-00, (7mm post) a little longer yet

part # 5JG-14940-16-00, (6mm post) I believe same as KTM

AND Here talks about hanging idles and decel poping

and Here- jd explanation of AP

The fuel from the accelerator pump after 1 second and out to 3 seconds may not result in a bog on the first throttle snap, but what about the 2nd, 3rd, and 4th throttle snap. How often you open the throttle and how fast the motor is spinning, along with the available air (as in elevation - or humidity) will all be major factors in whether the bike runs rich. The longer a bike is rich, the colder the motor gets, and eventually it can't burn an under-atomized stream of fuel (like pouring gasoline on a cold fire, nothing happens). However, if the jetting is extra lean and very hot, like an emissions needle, then it will tolerate a longer stream from the pump ---up to a point. This point shortens if you're snapping the throttle open on a stand, riding at high elevation, lugging the motor, evaluating a cold motor in the garage, etc.

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I would start with a compression test! If the engine needs help we can screw in jets forever and get no where.

If I where setting it up?

Pilot would be a #43

accelerator pump would be restriced to a one second squirt, many ways to do this, the diaphrams are no brainers, wondering if one of the links here shows how to do a BK mod. I like this as you don't need to buy anything and don't know what is available to you in that part of the world

What main jet it wants is totally dependant to what needle it has so we need to start there, it has 5 letters stamped in it.

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don't know what is available to you in that part of the world

Since Slovenia borders Austria, believe me plenty.

I've now read and am still reading all the given articles on the links, about all the possible mods, to create my own picture.

i will now thorougly examine the bike for comparison.

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I got almost full info on his jets.

Jet needle OBDTR (OBDER would probably be better).

main jet 178

pilot jet 42

main air jet 200

pilot air jet 100

starter jet 85

There is info on the BK mot on this links and much much more interesting reading.

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Just noticed you responded with Jet specs-

I would order an EMP needle, and a 45 pilot and 162,165, 168 mains

and would start as suggested previously- start with your 42, emp 4th clip, and 165. Just as a starting point... and adjust from there....

also check the AP timing and duration-

D series needles just don't have enough taper and often result in weak throttle responce from low to mid- where you ride in technical stuff mainly...Commonly they are replaced with an E series or with a JD set up..

As Dave suggested- compression and valve condition will prevent any adjustments from making substantial differences.

Hope this helps:thumbsup:

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The honda diaphram should make a big difference, it did on my 520, and besides its only $20 considering how much it cost I would say it's the best value for the money. The only thing is if you ride below a certian rpm for to long it will lean out the engine, if you want to know about that read through the accelerator pump stickies.

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