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xr400 overjetted? will it kill the top end?

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I have a 96 xr400 that I think maybe over jetted and it possibly making the piston rattle. I'm not sure if it is that or possibly the piston is loose in the cylinder. I have a 160 main jet and 162 secondary. Mods include a gutted air box,hot rod connecting rod,domed piston, and DG slip on muffler. Has great response but not sure if its over jetted for the mods. Piston sounds like its rattling when it warms up now and not sure if jetting is prematurely killing it? Any ideas?

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Only problems I'm aware of from too large of jets is fouling and possibly poor performance.  Too lean jetting will cause high temperatures and burn valves.

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Yeah i heard that lean conditions will cause a ping and hurt valves. I raised the carb needle and it wanted to flood and hesitate.

waaaay better now though. never burned out a piston....do you know if the piston will rattle if the cylinder is worn?

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If the bore is egg shaped and the rings are bad you could get piston slap I guess.

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I have a 160 main jet and 162 secondary.

 

A 160 main makes sense.

 

162 and secondary do not compute. I don't think you have a dual carb.  Maybe you mean a 62 pilot jet.

 

Pinging is caused by the domed piston.  You need higher octane fuel for that.  I would have a machinist cut the piston so you can run normal gas.

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