carb tuning wr250 83 please assist?

hello and happy christmas to everyone! from 3/4 to full throttle my bike seems to stutter and hesitatate a bit . please can some one assist me with whhat i need to do or adjust . thanks every one and happy new year

its running rich. its smoking a bit and plug is wet.

smaller main please

my main is 440 at the moment. so i guess i need to go down to 430?

im going to try a 430 main . wish me luck thanks

whats your ALT?? hard to jet a without knowing that...
i live at 5400 feet,,,my jetting is a little leaner then most.

i would really like to know the alt . i live in surrey uk . how do i find out the alt of my area please

alt states. 139.359m/457.215ft. please assist from here . thanks

I have a 84 WR250 which has a little different porting than a 83 model. I also have a CR cylinder head on it for more compression but here are my carb specs. It runs great at 1200ft to 4000ft. Pilot 45, main 410 at 1200ft. 400 main at 4000ft, slide 3.0, or close as I modified it myself, needle jet P-8 and needle- 6F16 with clip one up from bottom. Always starts cold within 2 kicks and 1 hot.

Silencer isn't getting plugged is it?

silencer is all good. im just a bit confused as to which jetting i need to have for my alt (as above). thanks

What is all your jetting in your carb? Just the main is very vauge as it all plays into tuning. With my bike at that altitude I would run a 410 but I would look at how much I would actually be running on the "main" also. Alot of times when I take my bike to the mountains I wont change the main because I'm trail riding and not WOT throttle very much. I might just drop the needle down a notch to clean things up.

im currently running 6f16 needle, -8 needle jet,440 main,45 pilot. 1.5 turns out on airscrew. at457.125 ft thanks

2 notches from bottom on needle .

He's in Croydon you silly Yanks....a small suburb south of London and home to the site of an airbase that whooped the Jerries in the war. Anyhow......
Pilot at 45 is fine unless it really struggles to get up into the top end. if and I mean if you do alot of tight technical single track you might think about a 40 or even a 35 if you are going fox hunting through the brambles.
6 f16 is one needle leaner than I run for my 82-84's but...
Me thinks your main is alittle fat....try a 430 and have a 420 and 410 handy if the 430 gives positive result but not quite what you want.
Make sure fresh gas, clean aif filter, and new plug(s) as well as ensure silercer sparky is clean and flowing (stock Husky S/A's clog like the M4 on a friday afternoon during caravaning season!)

Was stationed in upper Heyford in 80's
cheers
Joe

Slide? Your -8 needle jet is it a P8, Q8 or hopefull not a R8? P is the leanest which should be stock.

My quick test if I suspect to much main is drop the needle into a little more, if it cleans up your too rich! Maybe right or maybe wrong!

jetting and temps, altatude, and adjustment for summer months

alt is ,457.215 ft
temp, is 5 oc
main, 440 , plan to change to 430 due too being a bit rich .
45 pilot
p-8 needle jet
6f16 needle at 2nd from bottom , but plan to put in middle?????? good idea or not ?
air screw 1.5 turns out from seated . is this good or not ?
i hope some one can make me right on these figures . and quick question ....... will i need to re jet or adjust in the summer eg 25 oc approx thanks all

I would move your needle clip up as that will lean it some and that will tell you wether or not your going the right direction. Only make one change at a time that way you know what is working or not. On the temp. change I would get it right for the "now" weather and then make adjustments then. A stock engine isn't that picky on jetting. Husky manufactured these bikes to be sold all over the world in all climates and not get a bunch of warranty claims. The factory specs are usually safely rich to prevent engine damage. Most of the time just dropping the needle further down into the needle jet and main will clean them up!

Remember one change at a time!

Air screw at 1.5 is a good starting reference. I adjust air screw so engine is running at the highest rpm I then back down the idle screw to bring the idle speed down. I go back to the air screw and readjust again to the highest idle speed and bring idle screw back out to good idle rpm. This procedure ensures the pilot circuit is doing its job and the slide is closed enough for it to do its job. This keeps it clean at idle becaus ethe slide is closed enough for it not to be pulling fuel out of the othe intermediate circuits.

A carb. is just a air regulator for the engine. The amount of air, its velocity and fuel metering dictates the amount of fuel brought into the air stream into the engine. Example: Holding a bottle of water out the car window at 2mph, none comes out, faster the car goes the more air passes across the top of the bottle creating a vacuum effect across the orfice of the water bottle. This pulls water out into the air stream. The orfice at the top of the bottle is a "jet"! As we open the slide of the carb we are asking for more air demand and more fuel. The further we open the slide from idle the less we restrict the fuel to enter the airstream. Hope this helps, Scott

its just a case of playing with the needle clip to try and lean it out a bit. if no joy ill have to try the 430 main . what u think ? or shall i just put in 430 and put clip to lowest position and work from there? thanks all

I would just start moving the down one position at a time, clip up=needle down into jet further restricting fuel.