1997 ktm250exc jetting

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#1
Keep fouling plugs on this bike. Anyone have a good set-up for this bike? I have boysen reeds, FMF fatty, and low end port job, and ride in IL.

I currently have 170 main, 45idle, N85D at #4 clip. It almost always fouls at start up. When I put a new plug in it will run fine all day. I think I'm going to move the clip learner by two notches. Thanks guys
 

yarbonwick

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#2
You can try but in general the needle doesn't come into effect until 1/4 throttle. I'd reduce the 45 to a 42p and play with the idle screw - also don't leave the choke on too long. I always start up, then kill the choke after a few revs. Also, what plug you using?
 

CR Swade

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#3
On the 97 I had, the slide was the problem. Many KTM owners cut the slide 1mm if I remember correctly. Did mine and it cured it.
 
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#4
Yea-I always turn the choke off right away. I am using BR8ES.

I never heard of cutting the slide. Wouldn't that make it run richer?
 

CR Swade

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#5
Nope, leaner...more air being let in at the slide.
 

fishhead

die you sycophant !
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#6
Try dropping the needle first, one step at a time. the n85d is a triple taper so dropping a clip position effectivly leans the straight section diameter. This is one of the subtle nuances that makes tuning with triple taper needles so much fun.

Have fun!
 
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#7
I had the same problem. Just learn the correct starting procedure when it's cold. Put the choke on, do not open the throttle when you are kicking it over and it will start right away. When it starts do not give it any gas then after only about 10 seconds turn off the choke and then take off. I will run a little rich for a few seconds and then it will clean out.
 

CR Swade

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#8
If his 97 Katoom is doing hte same thing that they all did around here, it was not a cold-start foul. These bikes would foul for no good reason after 20-30 minutes to hours of operation. Altitude changes seemed to really aggravate the problem, even though the bike never spooged much at all. I had heard it had more to do with rather cavernous ports on the older engine design. All I know is the slide cut eliminated it.
 
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#9
Two opinions here. One for the pilot jet and the other for clip position. Does the air screw make a big effect? I found it was only out 1/2 turn.

How do you cut the slide? A dremmel tool maybe?
 

fishhead

die you sycophant !
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#10
Rather than agonize over which is right try one at a time and keep track of your results. Its no big deal to change a clip position or a pilot or an a/s setting.

My person preference is A/S, clip and pilot in that order because thats the order of difficulty.

Happy Jetting! :thumb:
 
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#11
Well, leaned the clip one position and leaned the air screw a little. Havent fouled a plug yet (3 rides). So nice not having to change it every time.

Is is surging a little in 1st gear after letting off the throttle. Is that caused by being a little too lean?
 

fishhead

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#14
could be a lean surge, try turning in the air screw a bit and see if that makes a difference
 
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#15
45 pilot, 170-172 main. air screw out 1.5 turns. DDG needle, middle position. Definitely a #7 slide - and be sure to use a BR8EG plug. The ES is more prone to fouling.