How high strung is it?


26 replies to this topic
  • Spam16v

Posted October 29, 2015 - 02:02 PM

#1

The reason I ask is I'm gluing one back together, an 05 to be specific. Still2smokin sold me a bottom end for the basket case I bought. I have a seemingly very good condition head, jug and piston. Not sure how fragile or raged edge these engines are.

Question 1, titanium valves, presume coated seats. Should I change stem seals? Valves are CRAZY money, should any service or lapping be performed? Or knock it off and leave it alone?

Question 2, piston/rings. I'm going to deglaze gently with scotch brite as it is a coated cylinder, any other method preferred? Rings, replacing them at a minimum, oem or? Piston, skirt wear seems non existent, replace or not bother? Oem or otherwise if I did?

Question 3, cam chain & tensioner. I was told oem chain etc. Are manual tensioners preferred or oem auto the way to be?

I'm coming from the DRZ world, have been reading there for ages and built a bunch of them. Reading the WR450 forums, there's not as much activity pertaining to engine building or I haven't seen it if so. Plan is a healthy stock build for a dual sport. Not wringing it's neck, the talent bucket isn't full enough to reach the bike's full potential. I am just certain I don't want to blow it up.

Thanks everyone.
-Zac

  • RiderDeAzul

Posted October 29, 2015 - 05:50 PM

#2

Coming from a drz, it will be more high strung like a race bike, especially with the free mods done, I have not found the need to do the mods (yet) I would recommend getting used to it before doing them

  • Slow and Jerky

Posted October 30, 2015 - 04:30 AM

#3

You can get allot more on the  YZ forum, since they are very similar engines most things apply. But for your questions (IMO):

 

1) If the valves are in good shape don't mess with them. You're not supposed to lap titanium valves, it take the hard coating off and ruins the valve. If you get new valves have the seats touched up. If you go to stainless you will have to get new springs and have the seats touched up. My experience has been that the OEM valves last a long time so I  generally leave them alone unless they are going out of adjustment routinely or don't pass the sniff test when you pull  them out to inspect.

 

2) Scotchbrite is okay, but an actual ball hone is is better. If the piston is good just put in new rings, but I would make sure to measure the piston very carefully. Make sure you check your connecting rod for play (vertically) while you have it apart.

 

3) Replace the cam chain, these are cheap and they do stretch. For $20 better safe than sorry. I have never had problems with tensioners.

 

I have learned over the years (the hard way in some cases) that OEM parts, at least for the engine, are the way to go. But having said that I have also had good luck with aftermarket cranks (Hotrods) and stainless valves. My best advice is to read the reviews on a particular product and check out the forums on TT.

 

These bikes take allot of abuse,  if you keep up on maintenance they are extremely reliable.



  • RiderDeAzul

Posted October 30, 2015 - 05:14 AM

#4

Cam chain for 20$? Do you mind posting a link to where? I'm looking to replace mine and cheapest i can find is 65$



  • Slow and Jerky

Posted October 30, 2015 - 05:26 AM

#5

https://www.rockymountainatvmc.com

 

I can't send a direct link because  the way the site works, but  you can navigate to it $20.06 for OEM



  • beezer

Posted October 30, 2015 - 06:13 AM

#6

People don't go crazy on modifying the 450 cause it's pretty fast as it is.

 

My WR450 with a pipe is way faster than my DRZ was with a ton of money into it.



  • Spam16v

Posted October 30, 2015 - 01:17 PM

#7

From the sounds of it, with my goal of reliability, hone it, just slam rings in it if the skirts measure up, get a fresh cam chain and be done with the damn thing.

I'm not worried about additional power with aftermarket parts, I just didn't want to ignore something I should change while its apart since the part was flawed or due for replacement as is due to risk.

Yeah, I had a 440 DRZ, big dick Webb cams, FCR, oversized intake valves, all that crap. My orange 250XCW is no comparison too.

Thanks everyone.

  • bikedude987

Posted November 02, 2015 - 06:15 AM

#8

Yup, keep the motor stock internally and you'll be a happy man.  Check the valves semi frequently, but they rarely move.  It'l blow the drz out of the water for sure!



  • Krannie McKranface

Posted November 02, 2015 - 07:10 AM

#9

Do not lap Ti vavles, or you will ruin them.

 

Hi rpm motors need the seats cut to match the valve profile.

 

Inspect the valve stem wiggle (guides), valve seat seal (with gasoline), and use OEM CAM CHAIN AND TENSIONER! 

 

You are not saving any money putting in a Chinese cam chain........in the long run.

 

You don't need to worry about the WR motor. I have built one to the hilt and it still lasts years longer than everything else....now approaching 650 hours and 4th piston....



  • Spam16v

Posted November 02, 2015 - 08:49 AM

#10

What's life expectancy or key point at which I need to scrap the piston? Prefer not to have one rock and lose the cylinder.

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  • jentzschman

Posted November 02, 2015 - 10:19 AM

#11

Coming from a drz, it will be more high strung like a race bike, especially with the free mods done, I have not found the need to do the mods (yet) I would recommend getting used to it before doing them

Definitely  NOT this, haha. DO the free mods. 



  • jentzschman

Posted November 02, 2015 - 10:20 AM

#12

Yup, keep the motor stock internally and you'll be a happy man.  Check the valves semi frequently, but they rarely move.  It'l blow the drz out of the water for sure!

Yep, I am SOOOOO glad I got the WR over the DRZ. 



  • Krannie McKranface

Posted November 02, 2015 - 10:29 AM

#13

What's life expectancy or key point at which I need to scrap the piston? Prefer not to have one rock and lose the cylinder.

 

You won't .

All depends on how you ride.

I get 150-200 on an oem piston.

You can't rock a piston on a WR. The skits are long. It's not like a CRF motor.....



  • GuyGraham

Posted November 02, 2015 - 12:25 PM

#14

You won't .

All depends on how you ride.

I get 150-200 on an oem piston.

You can't rock a piston on a WR. The skits are long. It's not like a CRF motor.....

 

 

errrrr...... http://www.thumperta.../#entry12697635

 

Plenty of YZ450F's which use the same piston have done it as well, in the local MX scene


Edited by GuyGraham, November 02, 2015 - 12:26 PM.


  • Krannie McKranface

Posted November 02, 2015 - 12:59 PM

#15

errrrr...... http://www.thumperta.../#entry12697635

 

Plenty of YZ450F's which use the same piston have done it as well, in the local MX scene

 

Well yeah, if you run a four stroke till it fails,........it FAILS.....!

 

If you run it out of oil it also fails.. Are you gonna give me examples of that too ?

 

The point is that the Yamaha WR MOTOR specifically, is the most bulletproof ever built. 



  • bikedude987

Posted November 02, 2015 - 01:50 PM

#16

I had a noticeable piston slap in mine when I replaced the piston.  Now with ~100 hours on the new piston and still tight.  

 

I went with a Wiseco to replace the OEM piston that was in there.   I forget how much wear was seen on the OEM, but you could hear it ticking with RPM, especially when cold.



  • Spam16v

Posted November 02, 2015 - 02:39 PM

#17

errrrr...... http://www.thumperta.../#entry12697635

Plenty of YZ450F's which use the same piston have done it as well, in the local MX scene


That guy set up a clutch wrong to send shavings everywhere and look at the sludge in the cooling jackets and oil drain cavity. I'm going to consider a fresh slug for mine when I look closer.

Edited by Spam16v, November 02, 2015 - 02:41 PM.


  • Doug06fx4screw

Posted November 02, 2015 - 02:44 PM

#18

errrrr...... http://www.thumperta.../#entry12697635

Plenty of YZ450F's which use the same piston have done it as well, in the local MX scene

It was stated by the OP in the thread you quoted, that the piston tilted due to beating it out of the cylinder due to being locked up. Edit, after rereading the thread, the marks on the skirt were due to the beating, not the tilt.

Edited by Doug06fx4screw, November 02, 2015 - 02:50 PM.


  • Spam16v

Posted November 02, 2015 - 02:48 PM

#19

You won't .
All depends on how you ride.
I get 150-200 on an oem piston.
You can't rock a piston on a WR. The skits are long. It's not like a CRF motor.....


This engine had aluminum go through it. I'm only using the top end from it. I see some scratches in the skirts and wear above the top ring on the exhaust side. I want to stick with oem compression so oem piston it is. Cylinder is going to get washed in the clean parts tank at work, rinsed and reused along with the head. It'll be right when it's done.

  • Krannie McKranface

Posted November 02, 2015 - 08:12 PM

#20

Coming from a drz, it will be more high strung like a race bike, especially with the free mods done, I have not found the need to do the mods (yet) I would recommend getting used to it before doing them

 

Actually a DRZ revs about as fast, if not faster than a WR. It just has 50 more pounds and 15 less hp.

 

An uncorked WR high strung?  Maybe with $5k in motor work....it's about as docile as a 450 can be and still have torque. Probably, only the KTM500 is more docile in power delivery....






 
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