question for honda mechanic

4579 Views 3 Replies 2 Participants Last post by Honda Mechanic, Aug 5, 2007

hky5004x4

Discussion Starter · Aug 5, 2007

i have a 06 foreman 500 ex 4x4 the shop said they bored it .25 over about 200 miles ago but is is smoking bad again i took the piston and cylinder to anouther shop becaues the one that bored it frist resused to warranty it again the 2nd shop i took it to said it had been bored .50 over and a .25 over pistion and rings put in it they sent it to be honed and were gonna put a .50 piston and rings in it the machine shop called back and said the piston was standard bore and it needed to be bored .25 over is ther any way by looking at the letters and # on the piston i can tell what size pistion it is and should the piston be widder at the base of the skirt on the frount and back than the sides or the top of the pistion the piston has thes markings on it on one side it has hf 1 and in on the outher side it has hpo and an A can some please tell me if this is a standard or an over bore pistion thanks.

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Honda Mechanic

· #2 · Aug 5, 2007

The piston should have a .25 on it if it's 1st. over or a .50 if it's 2nd over ... HPO identifies it as a TRX500FE/FM/TM piston ..On the TRX500 you measure the piston 15mm from the bottom of the skirt..

If you have a motor and it needs to be bored you must get the piston (whatever size you need) then take the piston & cylinder with the clearances you want to the engine or machine shop , that's the only way to be 100% sure the clearance will be right .. Honda also recommends that once it is bored the final hone should be done with nothing courser than #600 stones for max engine life..

If you want the 2005-06 piston/cylinder section from the Honda PDF shop manual just PM or post your email address ...

Here is a picture of a 1st (.25) piston for a TRX450 you can see the .25 etched into the piston top .. On this piston HNO means TRX450 model

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hky5004x4

Discussion Starter · #3 · Aug 5, 2007

Thanks for the info and please email me that info to [email protected] what should the clearance between the new pistion and the cylinder wall be after it is bored and honed thanks for you help.

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Honda Mechanic

· #4 · Aug 5, 2007

The clearance should be:

0.015 - 0.045mm (0.0006 - 0.0018in)

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