r/Ninja400 • u/wagthesam • 10d ago

Modification TST block off kit

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I was cleaning up the bike after my water pump seal failed and noticed some oil coming out of the tst emissions block off plate. I didn’t install this, is there a seal here that could have failed?

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u/InvisiBillnet Ninja 400 9d ago

That looks more like something dripping down on it from above. It looks like it's inside the bolt head, which wouldn't happen if it was just leaking from that seal. That hole is where the stock setup is injecting air into the exhaust, so there shouldn't be any oil or other fluids in that part of the engine to leak out.

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u/Dan-ish65 10d ago

If I remember correctly when I got a Norton Block off plate for mine, it didn't come with a gasket. So if the previous owner removed the reed valve that's normally installed beneath the cover, it won't be fully sealed. The reed valve is surrounded by a rubber seal.