Well heres my prob my zilla is hard started and when started takes to rev itself out. The plug comes out black and oily so I take it that it is runnin rich! I've got airbox vents, k&n,fmf torque reeds, wiesco 1mm overbore piston, the head was planed and it has a dg exhaust and I'am 250feet above sea level so any suggestions where to start jetting.And i've just finishing fully rebuilding it. I don't really understand jetting all that welll and was wondering about dial-a-jets are they useful/useless. Any info is greatly appreciated

 

So you finally got the Zilla back together? I see its an 87 I would suggest starting with a #400 main jet and a #30 pilot jet that should put you real close. You say its reving high make sure your throttle cable isnt hanging up. As far as the dial a jet I have not used it before maybe somebody else can give you some feedback on it. But I am glad to see you have it running my 87 is almost done look at my pic's I will post some of my 87 later.

 

Yeah shes almost there. As for the revving it just takes off herself without me touchin the throttel but she comes back to idel when i give the throttel a dart. I must inspect the cabel and put a bit of wd40 down it. Is there a pecific jet set for the zilla or can I just buy any jet kit with thoes kinda numbers in it. If I remember correctly it has a 420 main at the moment I think. I wanna get her runnin perfectly. My kx has a lovely brown colour on the plug. BTW rooster that is one sweet zillla you have I never thought Yellow could look as good on a zilla, I used to be put off with original coulours and you'r engine looks fantastic! And you've got 3 ZILLAS can I be you'r friend!!!!!LOL!!!!!

 

Emerald I would suggest going to a 400 also pick up a 380. You should be able to pick up jets at any motorcycle shop for a mikuni carb mikuni uses there own set of numbers. Kiehn carbs are different numbers so get jets for mikuni carbs and you should be good to go. Just remember temp and elavation are what changes jetting a 400 or 380 would be for temps above 75 and as it gets colder you can go up in size in winter run a 420 to a 440 in the 87 hope that helps.

 

i cant help you out on the carbs specs on the zilla,but i did ran dial-a jet some years back then and the main thing is to dial your carb/jetting
when
the setting hole is at the mid of the dial a jet,that way it will run better as you can go up or down some few larger jet size,when time come to lean or richen depending on the temp,a lot of spark plug testing
is needed to get the correct main jet but that not hard time to do,sorry
for the little infos...

 

My lt250 is doing same thing, or it was. I put diff carb with same main an it stopped doing that. I know that 2 stroke wind up when lean on air/fuel mixture so maybe it's running lean initially.

 

Sorry I havent been on lately(i'm back at school and gotta do homework). I'd doubt the dial-a-jet would be a great advantage to me I think because temp ranges aren't great here, it averages around 10-15 degrees celcius. I hope to get a few jets this weekend and try it out will let you know.thanks for the help.

 

Dial a jets work great if you ride in different areas at diff elevations, temps, etc, etc.
However, your baseline jetting still needs to be spot on before it'll do you any good. Then it's basically a few clicks with a screwdriver to 'dial' it in. I've tinkered with one, and it worked pretty good.

Once Again (I'm starting to sound like a broken record), It's not wise to just use what someone else uses for jetting (Size wise)... There are too many variables and you could end up smoking your brand new engine.

look here: http://www.eric-gorr.com/twostktech/carbtuning.html

Learn how to tune your bike, and actually understand what/why you are changing. That way you have a chance at actually getting it tuned PROPERLY.

My $.02

 

Thanks for the link I don't fully understand jetting but now I have a good idea. If it gets too much of a job for me I'll prob bring it to a garage and just pay them might be easier.