Athena bigbore 470 (or 435?) piston lifetime?

Hello, I just bought a 2000 DR-Z 400 with Athena bigbore kit. The original owner told me it is 470ccm, but I heard that 470´s are not made by Athena and my cylinder says Athena, so maybe it is just 435ccm. But my question is, how long do pistons in those kits last until they need to be replaced? Thx for answers.

Does it have a 94mm cylinder-piston/big bore kit and a stroker crankshaft ?

This is a '470 .

Athena makes a 94mm(434cc) bb kit only .

Athena uses a 3ring piston manufactured by Wossner , they are ok to use for many kms , like the oem one .

Does it have a 94mm cylinder-piston/big bore kit and a stroker crankshaft ?

This is a '470 .

Athena makes a 94mm(434cc) bb kit only .

Athena uses a 3ring piston manufactured by Wossner , they are ok to use for many kms , like the oem one .

WHAT is a '470?

I dont know the size of the piston, I didnt have the cylinder head down yet. So id doesnt need often replacement like pistons in KTM´s etc? And what about valve clearances, are they the same as for standart DR-Z?

Search for stroker motor and you will find out how you get a 470cc motor( really a 462cc now).

It uses a Big bore Kit and a longer stroke crank to increase the cc of the motor. If done right, they are reliable as anything else out there.

i had to tear mine down this winter and the piston looked just fine.i had 12k kms on it of hard miles

a good quality piston will last if you keep the dirt out and the oil fresh

Hello, I just bought a 2000 DR-Z 400 with Athena bigbore kit. The original owner told me it is 470ccm, but I heard that 470´s are not made by Athena and my cylinder says Athena, so maybe it is just 435ccm. But my question is, how long do pistons in those kits last until they need to be replaced? Thx for answers.

Yeah..it would have a +4mm crank to make the 470cc...Has the PO shown you documentation to support his 470cc claim...???

I suggest using full synthetic oil, change it and oil filter every 1000kms...

The piston in my 485 is looking very average at 10,000km piston replacement intervals...The skirts have considerable wear...I Will change piton at 7,500kms next time...

I check valves mid way thru piston replacement intervals..i.e. @ 4 to 5,000kms...

BTW..Welcome to TT.....:smirk:

Cheers,Craig

I ride offroad only so I plan to change oil and filter every 20 moto-hours.

But I dont know how often to check valve clearances and to what values set them - the same as for normal DR-Z, 0,15mm and 0,2mm will be ok?

Owner claimed the big bore kit was installed before 2500km´s and he didnt check the valves after that, it is time to do that now? Maybe it is more than 2500, there is no way to prove it.

When u replace the piston, do you also have to rebore the cylinder? Does it have NiCaSil?

I ride offroad only so I plan to change oil and filter every 20 moto-hours.

But I dont know how often to check valve clearances and to what values set them - the same as for normal DR-Z, 0,15mm and 0,2mm will be ok?

Owner claimed the big bore kit was installed before 2500km´s and he didnt check the valves after that, it is time to do that now? Maybe it is more than 2500, there is no way to prove it.

When u replace the piston, do you also have to rebore the cylinder? Does it have NiCaSil?

If you have the oem camshafts, the clearance should be .10-0.20mm on the intake and 0.20-0.30 on the exhausts.

I would check the clearance now, just to make shore it's ok.

You don't need to replace the piston for a long time, if you keep the oil fresh, changing it every 2-3000km's, you should be fine.

Cylinder has nicasil, so a re-bore will cost you more than you would like.

When changing piston rings, a ball hone will usually be more than enough, if the cylinder isn't too scratched.

These engines are incredible solid, just do the fixes in the faq on top of this forum, and you will be ok :smirk:

If you have the oem camshafts, the clearance should be .10-0.20mm on the intake and 0.20-0.30 on the exhausts.

I would check the clearance now, just to make shore it's ok.

You don't need to replace the piston for a long time, if you keep the oil fresh, changing it every 2-3000km's, you should be fine.

Cylinder has nicasil, so a re-bore will cost you more than you would like.

When changing piston rings, a ball hone will usually be more than enough, if the cylinder isn't too scratched.

These engines are incredible solid, just do the fixes in the faq on top of this forum, and you will be ok :smirk:

How do I find out if I have oem camshafts?

I knew these engines are solid when original without changes, didnt know what about when bigbored. I´m asking all this because one mechanic told me that my engine sounds like the piston is loose in the cylinder...

Stock cams hasn't any bolts on the sprocket :

DRZ400SM1505Engine023.jpg

on the other hand HotCams (which are the most common aftermarket cams) have two bolts on each side of the sprocket :

hotcams-yamaha.jpg

How do I find out if I have oem camshafts?

I knew these engines are solid when original without changes, didnt know what about when bigbored. I´m asking all this because one mechanic told me that my engine sounds like the piston is loose in the cylinder...

No difference in solidness with/without big bore.

You can have some piston slap, not unusual on these bikes.

Thx, what clearances should I set if I have those HotCams?

No difference in solidness with/without big bore.

You can have some piston slap, not unusual on these bikes.

Great, I thought it is a sign that the piston is near the end of its lifetime...

Thx, what clearances should I set if I have those HotCams?

IN .15mm

EX .20mm

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