Does new OEM cylinder and piston need to be matched?


8 replies to this topic
  • bigcam

Posted October 04, 2015 - 11:51 PM

#1

I have searched and searched and cant find a actual answer for this. Is all i need to do is buy a new OEM cylinder and new OEM piston and rings slap it together and go or does the cylinder and piston need to be matched like we did with the old steel sleaved machines?

 

I really do feel stupid asking this question. Iv built several engines but this plated stuff and all my options with plated cylinders im still behind the times. Please bring me up to speed a bit here.

 

This is on a 2000 WR400.

 

 



  • ttreewalkerr

Posted October 05, 2015 - 05:22 AM

#2

I have a weisco piston kit arriving today in mail. I did use calipers to make sure I have a 95mm bore, not bored out. Other than that I used scotch Brite pad by hand on cylinder, washed it out with soap. Gonna gap my rings, nothing special,,, and slap it in.
Those pistons are so close to the same that a hand caliper can't measure the variation. Slap it in and go.
You do have to gap rings though,, that's a fact.

  • bikedude987

Posted October 05, 2015 - 06:54 AM

#3

If you want to do it right, go get the bore measured with a bore mic and the piston with an outside mic and make sure of your clearances.  Being that they are both new OEM, I would not worry about simply assembling though.



  • Krannie McKranface

Posted October 05, 2015 - 07:54 AM

#4

You have a hard plated bore

Unless you have re-bored it and re-plated it, you just need the original OEM piston kit.

Try to avoid the chinese pitons kits ( basic Wiesco, etc) and learn how to do the ring gap filing and gap orientation too.

If you cannot see cross hatch marks all over the bore after cleaning it up, you need to re-cross-hatch the bore.



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  • bigcam

Posted October 05, 2015 - 10:23 AM

#5

No way id ever put chinese parts on this bike. The idea here is make the topend new! just as it was from the factory. I had one years ago i bought nearly new and it was a trouble free bike for years. I literally just did maintenance and rode it. Never had to repair anything aside from something like a brake lever if i laid it over. Well i sold that bike didn't ride for several years and now have found the very same year make model as i had witch is a 2000 WR400. Sept now these bikes are kinda old these days. I liked the first one and want this one to be just as reliable as the first. Im not afraid to spend the extra money or even maybe waist a little money to make it like it was 15 years ago. It runs and rides now i could probably clean up the cylinder on it and put in some new rings but id rather go all new OEM so i have a fresh start. I could then use the old cylinder if good as a backup incase something happens to the new one. Just wanted to be sure with these plated cylinders i could just buy all new do the ring gap and run and not be doing something that would make it not last.

 

So the total plan is New OEM cylinder, New OEM piston and rings, new OEM cam chain, Check valves, cams, crank, and aything els i have my hands on during the work. Replace anything worn with new OEM parts. Also plan to find a better exhaust for it but i planned to make a thread about that later on. Then go ride for the next several years without issues :)



  • bikedude987

Posted October 05, 2015 - 12:41 PM

#6

Unless it's really clean/tight, I'd go ahead and do the valves while you're in there.  For another $5-600 you will have a like new head that will last many hundreds of hours.



  • bigcam

Posted October 05, 2015 - 01:39 PM

#7

Unless it's really clean/tight, I'd go ahead and do the valves while you're in there.  For another $5-600 you will have a like new head that will last many hundreds of hours.

Thats part of my plan. Wouldnt think valves would cost that much tho? I want to be a bit picky on it. Spent $200 on just chain and sprockets on this bike. I may not be rich or have much money but cutting corners for cost is not going to happen on this bike. only the best or what has proven to do what i want.



  • bikedude987

Posted October 05, 2015 - 06:50 PM

#8

Thats part of my plan. Wouldnt think valves would cost that much tho? I want to be a bit picky on it. Spent $200 on just chain and sprockets on this bike. I may not be rich or have much money but cutting corners for cost is not going to happen on this bike. only the best or what has proven to do what i want.

 

No, but by the time you get done with cutting the seats, you usually need new guides, sometimes new seats installed, shipping both ways, it's somewhere around $500.  Just be thankful Yamaha used steel valves in those heads OEM rather than Ti.  The newer motors are into just the valves for about $360...



  • bigcam

Posted October 06, 2015 - 02:32 PM

#9

No, but by the time you get done with cutting the seats, you usually need new guides, sometimes new seats installed, shipping both ways, it's somewhere around $500.  Just be thankful Yamaha used steel valves in those heads OEM rather than Ti.  The newer motors are into just the valves for about $360...

I got a local shop here that can do the machine work and such.






 
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