1983-84 kx 250

[Tecate250]

I need some help with my 1985 Kxt 250. I need to know what is needed to put a stock 83 kx 250 carb on my tecate 3 wheeler. I have gone through 3 pistons in the last year. I did have parts almost enough to build 2 tecates minus a crank and odds and ends.
I did have the stock t3 carb but was lost when I sold it.
It does not have the kx cylinder so Do I need to under jet the carb?
I have the folling mods.
V Force 2 reed cage (  Tecateconnection.com says these cages with the grey backer will break)
Wiseco max bore piston
1983 Kx 250 stock carb
1988 Tecate 4 Stator
Ricky Stator Magneto
Uni Air Filter
Mild port work
Bassoni Head pipe
Dg Silencer
It had over 200 psi after rebuild
Here is a pic of #3 piston after running it for 3 months



Now it has 150

[Tecate250]

Does anyone know the stock settings for the 83 kx 250 carb?

[CR480R]

Why fool around with an old POS round-slide mikuni?  Find yourself a cheap Keihin PWK.... and learn how to change jets...

[Hillclimb#42]

Its weird. First, my manual left out setting for '83. Second, it lists '82 and '84, but they are way different. I'll give them both to you and maybe you can figure which one you have by the sizes in it. both are size VM38SS
'82 has 165 main, jet needle and position is 6I2/3, needle jet is R-8, slide cut away is 3.0, pilot is 15
'84 has 320 main, jet needle and position is 6J4/3, needle jet is R-2, slide cut away is 3.0, pilot is 30

This is weird to me that the sizes are almost double, but this may be the issue with the burnt up piston in three months, if you are under carb'd. CR480R may have a point about using a better carb if you have small set-up. '85 and '86 stay bigger on the sizes.

[KXcam22]

Also try Sudco. They used to market carb kits for various bike and might have made one for that model.  I once upgraded an old Maico from a bing carb to a VM38 Mikuni.  Sudco gave me the exact mikuni jetting specs from their kit over the phone. Cam.

[Tecate250]

And actually the carb off the 83 kx 250 is a round slide Keihin PE carb. I had a carb off a 1988 Tecate 250 4 wheeler. It was a keihin flat side carb but made it so you always had to be on the gas. Even going down hills. That sucks. The carb settings I have is a 160 main jet the other is a 60. It is hard to get jetting down when you have no idea which way to go. I can't afford to buy all kinds of jets to mix match to work.Anyone know what did my piston in?

[Hillclimb#42]

Well that's different. Kehin,in '83, is 160 main and 60 pilot,N13 needle. I saw Mikuni and gave spec. on that. That piston had to be runnin lean to melt down. Straight gas accidentally? It happens, but I'm not trying to insult your intelligence, at all. Could it be running too hot? or what oil were you using? My piston looked better than that after my slide hung open and blew it up. Did it act crazy during start-up? or before it died? I assume that it did quit ya'?

[Tecate250]

Well actually the bike ran great till about 10 sec befor it blew up. Sounded like a rattle. Anyways It has never seen straight gas. Only the oppisite. Lots of oil. I ran it at 20/1 all the time. I use ultramar gas station oil in all my 2 strokes. I had bad luck with "good" oil. Never had a problem with this stuff. I have 2 pistons that look like that. Both were out of different cylinders and different cranks.