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Discussion Starter #1
Hey if anyone could help I’m having a problem finding what jets to run in my ltz 400 I have a 13:5:1 high comp piston an a lexx mx exhaust can anyone help me get it dialed in ?
 

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You running an airbox? Do you have a jetting kit with needle? What altitude are you running at?
 
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Yes I have air box an no I haven’t purchased a jet kit yet an my altitude is 683 ft
 

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Assuming everything else is stock, including the carb, I would start with a DJ25 pilot and a DJ160 main, needle on 3rd clip, and mixture screw 2 turns out. You’ll probably have to run higher than 92 octane.
 

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Assuming everything else is stock, including the carb, I would start with a DJ25 pilot and a DJ160 main, needle on 3rd clip, and mixture screw 2 turns out. You’ll probably have to run higher than 92 octane.
So Ill have to run race gas from my power sport dealer ?
 

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Above 12.5:1, you run the risk of experiencing detonation at low throttle. You’ll probably also need a colder plug, like the CR8E from NGK (CR7E is stock). Do you have the single-layer base gasket or stock triple-layer base gasket under the cylinder?
 

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Above 12.5:1, you run the risk of experiencing detonation at low throttle. You’ll probably also need a colder plug, like the CR8E from NGK (CR7E is stock). Do you have the single-layer base gasket or stock triple-layer base gasket under the cylinder?
Stock
 

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I’ve always understood it that advertised compression numbers for pistons were when using the single-layer gasket. If that’s correct, you’re not quite 13:1. More like 12.8:1 or something. CFM and Amcf18 know the particulars better than I do. Hopefully they’ll chime in.
 

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I’ve always understood it that advertised compression numbers for pistons were when using the single-layer gasket. If that’s correct, you’re not quite 13:1. More like 12.8:1 or something. CFM and Amcf18 know the particulars better than I do. Hopefully they’ll chime in.
Okay thanks for the help I hope they do I’ve been battling this problem for a while so should I order the dj kit ?
 

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You can, or just pick up the jets separately if you already have an adjustable needle. They’re about $6 each, way cheaper than the kit.
 

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Discussion Starter #11
You can, or just pick up the jets separately if you already have an adjustable needle. They’re about $6 each, way cheaper than the kit.
It’s still the stock needle idk if their adjustable could I just buy a adjustable needle ?
 

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You can buy that individually as well. Stock needle is not adjustable.
 

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I agree with Jet on this.. Your compression should be .9 below advertised with the Z base layer, putting you at 12.6.
If you get any detonation on hi test, you will have to mix some race gas in, or go to race gas period. You might be ok though. With air box lid off, I think a DJ 160 would work for you , but will be rich with the lid on. Better to start safe and work down though. This is with the DJ adjustable needle though, might need to go richer for the stock needle.
 
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