Head Work


7 replies to this topic
  • motodiver13

Posted September 09, 2009 - 10:58 AM

#1

I need to clean the head on my '98 WR 400. If I disassemble the valve train do I need to Lap the valves in when I re-assemble?

Also, does anyone know a source for rebuilt cranks?

Thanks

  • wondermuscle

Posted September 10, 2009 - 06:51 AM

#2

Your 400 has steel valves right? If so I 'think' you lapp them but I'm not 100% sure, you will need to cut the valve seats and who ever does that will know.

I ended up just buying a new crank, as getting one rebuilt was only $75 cheaper and was faster and more reliable than getting one rebuilt.

  • motodiver13

Posted September 10, 2009 - 08:14 AM

#3

Thanks- Did you go OEM or aftermarket? If you went aftermarket, where?

  • wondermuscle

Posted September 10, 2009 - 11:38 AM

#4

Thanks- Did you go OEM or aftermarket? If you went aftermarket, where?


I went OEM. The aftermarket I believe are simply rebuilt cranks and not newly designed and tooled components. But I'm not certain....

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  • pablo83

Posted September 12, 2009 - 08:01 PM

#5

If I disassemble the valve train do I need to Lap the valves in when I re-assemble?

You don't NEED to, but it's very cheap and easy to do and it won't hurt. Also, you don't need the valve seats re-cut unless you are having seating problems. Lapping will help determine if the valves are not seating properly.

  • wondermuscle

Posted September 13, 2009 - 04:14 PM

#6

Only STEEL valves can be lapped. If you lap a Ti valve you will ruin them, it damages the hard Ti coating.

  • JSanfilippo

Posted September 14, 2009 - 12:22 AM

#7

I'd get the seats cut and valves lapped. Why not go for the best possible seal while its apart?

  • motodiver13

Posted September 16, 2009 - 08:04 AM

#8

Thanks for the info guys. I think I am going to part out the bike. I got it cheap and it need a whole new bottom end, crank, bearings, etc...




 
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