Howcome my chain is breaking so much? It amazes me because it was breaking continuously then everyone was saying that it was bad axle bearings. So I had them replaced. Now today I started it I figured it was already warm because I just ran it a few hours before so I only let it sit for a minute then I shifted into first and the chain snapped right when my clutch engaged???

 

I would guess you also checked the sprockets for missing teeth when the bearings were changed. Are the sprockets properly aligned? Correct tension? Positive it's the correct chain?

Just a couple things to check. Hope you get it fixed.

 

I just changed both sprockets and the chain has like 1 hour on it. The front sprocket is volar and the chain is a 520 volar, the rear sprocket is sunstar. The chain has a bigger master link.

 

New chain and sprocket that's odd. Lots of those ATVs around and I never heard of a chain issue.
The Suzuki LTR 450 uses the same 520 chain.
Do you ride like a maniac ? Might be time to move to a 530 chain set up.

My old 1100 gsxr could not break a 530 your z400 better not.

 

I would question the quality of that chain. A new 520 shouldn't be breaking unless something is grossly wrong with the machine or the chain is of poor quality. 520 is more than enough for your Z. I am not even sure any other quads have ever come stock with a 530 except maybe the DS650?

 

I'm thinkin about gettin the 530. Would a o-ring chain be better because that's what the previous chain was and that never snapped?

 

The o-rings(or x-rings/whatever) help keep dirt and mud out of the pivot points on the chain. They extend service life, more so in muddy and grimy conditions but have little to do with the tensile strength of the chain. A 530 is a waste of your time, and it will hurt performance because of the extra weight. There are a multitude of quads making 2x your hp running 520s, I really don't see the need on a Z400.

 

How tight is your chain? Should have about 1.5" vertical play.

 

I keep thinking it's either a tension issue or the sprockets are off.

 

Same here. The only other thing I can think of is the swing arm bearings being totally smoked. Thus making it a alignment issue. Op can you post a pic of the top of the chain slider.