I have a 2003ltz 400 quad and think it it's jetted wrong does anyone know what size jets to use with the intake and exhaust thanks for any help it's driving me crazy

 

Welcome to the site. Get a (Dynojet) kit , then you will have instructions, you can also talk to an expert there. I'm putting a cam in my Arctic Cat 500 (Suzuki) and will be rejetting with one of their kits.

 

Parts breakdown shows a small round Mikuni 60 main as stock. Rule of thumb on a filter and exhaust up grade is 10/15% jump on jetting. Usually can get by with just jumping the main jet.67.5 or 70 main should be enough. You might try that and plug chop to see if the plug is tan to light brown. Just my two cents,haven't been crazy about Dynojet kits when the first one I installed years ago had the Mikuni or Keihin jets numbers had the sizes removed and their own set of "sizes" etched on them. Basically your paying high dollar for the titanium needle and not much more. If the carb is truly screwed up,plenty of brand new ones are on ebay for $89 where you can start out fresh.2003 2004 2005 2006 2007 Carburetor for Suzuki LTZ400 LTZ 400 ATV Quad Carb Y | eBay https://jetsrus.com/a_jets_by_carbur..._selection.htm

 

That's good info, old polaris tech! BTW, by looking at our avitars, we must be related, haha.

 

You're almost as old and ugly as I am,almost..

 

Depends on many variables, elevation air box lid on or off. Is it a full exhaust or slip on is it the factory carb or aftermarket. Stock for the majority was a 130, they were completely corked up from the factory. I put Yoshi slip on and uni air filter with air box lid off and went to either 150 or 155.

 

Kinda what I was thinking,but the breakdown shows a 60 main jet,22.5 pilot which sure seemed small to me to begin with. Items #42 and 48.http://www.cyclepartsoutlet.com/fich...003&fveh=10114 Plus it shows the pilot air jet under the ring where the main jet usually is.. #18 on the breakdown.Screwy parts break down list.
Just looked on Partzilla and they have it right! 130 main jet and starter jet is a 60..http://www.partzilla.com/parts/searc...TOR/parts.html

 

The #60 is the starter jet looked at carb parts diagram. 130 is the main jet unless dealer had to change for altitude location of dealership. Are these the parts on the bike or looking to install. An FMF jetting guide I looked at shows 158-160 with lid snorkel off, they probably meant with lid off, their suggestions are to get u close. What's the bike doing to think its jetted wrong, more info is needed.

 

Not a slip on bought it used. Elevation two thousand feet wasn't sure how many sizes to go up I will go with the seventy and see how it works thank you so much and lid is off

 

The jet you are Referencing going with a 70 is the starter jet, the main if you're putting the parts on from factory exhaust is a 130 you should probable get 150 or 155 or both. My lt 80 2 stroke has a 90main jet. 400ex I believe come with a 145 main, my Yoshi slip on suggested 150 to 155 fmf's jetting guide suggested 158-160 for your bike.