n00b Jetting Questions

A reference for the PWK carbs...
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jack_ellis
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n00b Jetting Questions

Post by jack_ellis »

Hi Guys, what a great forum!

Here's whats up:

I have a 1998 KDX200 which needs quite a bit of work. It's running but I'm sure it could be better.

I have currently a 48 Pilot and a Main jet 160
Needle on the 3rd position

I'm riding in Wales UK . 116m above sea level.

The problem i'm getting is a crappy top end. at higher revs just poops out. It's fine for working under 15mph but as soon as you want to get a bit faster it's not great.

I set the air mix screw at exactly 4 turns out. I set it like that because the engine revs were highest at that point when idling. Was that the right method? That's how I've set my 4 stroke road bikes before.

Spooging too.

Do those jets seem a good start point you reckon?
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Julien D
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Re: n00b Jetting Questions

Post by Julien D »

Tuning the airscrew out to highest idle is just to determine if the size of your pilot is appropriate. 4 turns would indicate that you need a leaner pilot. After that the airscrew needs to be adjusted for best off-idle response, not fastest idle speed. 160 is probably large on the main, as well. The only way to get it dead on is to follow the jetting guide.

http://www.kdxrider.net/forums/viewtopi ... 105&t=1156
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canamfan
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n00b Jetting Questions

Post by canamfan »

You sound rich, Over here in the usa runnin about 145 main, 40 or 42 pilot around 500 ft above sea level.
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Jaguar
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Re: n00b Jetting Questions

Post by Jaguar »

check engine compression and that the crank seals aren't leaking.
change the spark plug also.
clean the air filter.
make sure the silencer isn't clogged up.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
cornishwrecker220
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n00b Jetting Questions

Post by cornishwrecker220 »

Mix a fresh batch of fuel & oil ( 40.1 ) & a clean & oiled air filter along with a new spark plug.
Pilot jet ...42-45
Main jet ...152-155
Needle in the 3rd position or 2nd
Air screw ...1.5- 2 turns out

If you are not running the air box lid then the main jet may need to be increased to 155-158 if you use a lot of full throttle !
jack_ellis
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n00b Jetting Questions

Post by jack_ellis »

Brill, I wish I could try it out now! I have just ordered a few jets on your guys suggestion. will try them out and see what happens after resetting the air mix.

Fresh plug just in, air filter replaced and re-oiled

Reeds? can these mess up and give those kind of symptoms? it's on my to-check list

The airbox as far as I know is standard and un-modified.


Many thanks,
Jack
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