2011 YZ450 valve check

Thought since it had been 50 hours since I last checked the valves I would go ahead and check......Just got through checking the clearance on the Intake valves an the Exhaust ones.

On the Intake valves I could get the 0.10 feeler under the outside Intake valve good but did feel kinda easy but you could still feel drag. I then tried the 0.15 feeler but no way was it going under it.

Moved to the inside Intake valve an it was the same feeling as the outside one but may be a smidge easier......but not bu much. Same here.....the 0.15 wasn't going under either.

Exhaust valves were the same feeling as the intake ones and had the same feeling of drag.

Also the 0.25 feeler gauge wasn't going under either.

So Im guessing they are all ok. Guess when I cant get a 0.10 feeler under the intakes and a 0.20 under the exhausts .......then thats when I will need to reshim.

Since the bike has 85hrs on it now I was thinking about just freshening up the Top with A Piston/Rings, Timing Chain. Figured everything will run $250ish. I will be on here a bit showing pics as I go but wont start on it till maybe a couple weeks.

If there is anything I might need to look out for "Valve" wise......Let me know. Like if I should replace them or any of their parts ....like retainers collets ect...

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Edited by CaptainKnobby

Well I just went ahead and ordered the parts for the Top. So guess I will be starting on it this weekend.

Wonder if I will need a Flex Ball Hone?

Yes you will if you want this kind of result:

 

worn_zpsd05271f0.jpg

 

honed_zps69da51cf.jpg

Gray!........which size will I need? I know to get the 320 grit an the AO one (Aluminum Oxide) just don't know MM size.....Guessing 90 to 95mm.

Your bore size is 97mm, so you need one listed for 97mm bores.  If 97 falls between listed sizes, use the next larger size.

 

Silicon Carbide or Aluminum Oxide

Called my buddy down at the Yamaha shop and said he didn't have a ball hone for nikisil. Told me I probably wouldn't need it or he wouldn't use one on the cylinder. Said to just throw a piston and the rings in it and it would be fine........Lol.

You know .......I'm talking to someone that is all about the stock form. Meaning.......He likes to keep everything stock an is against anything after market and if it isn't broke don't fix it.

He is a real good mechanic and has around 30 years as a bike mechanic.

I was telling him about the measurements on my valves and if I should take them out an inspect them when I have the cylinder off. He said if they measured the way I said that he wouldn't even touch them........Or even look at em ......matter of fact run from them lol.

Any ways I will at least take the cylinder off an look at the piston and measure everything and take pics as I go along and post them up for everyone to see and to get opinions back on things.

This will be the first attempt on tearing down the Top end of a Four stroke for me. So it will be a learning experience for sure. I have been watching the motto power video and it doesn't seem all that complicated. Just things to look out for I suppose.

Called my buddy down at the Yamaha shop and said he didn't have a ball hone for nikisil. Told me I probably wouldn't need it or he wouldn't use one on the cylinder. Said to just throw a piston and the rings in it and it would be fine........

 

It's your bike. 

 

He might have 30 years experience, but he's wrong on this one.  (I have over 40.  So?) The reason he "doesn't have a ball hone for Nikasil" is because there is no special or different hone for Nikasil.  The bore in the before/after pics was done with the basic bottom of the line 280 grit silicon carbide Brush Research hone.  The finish you see is the product of less than 10 seconds of actual spin time on the tool.  And yes, the hone may actually wear faster than the bore does, but remember, you are not resizing or reshaping the bore with a ball hone.  In fact, the entire concept of the tool is specifically that it will not do either of these things.  The idea is to restore the correct finish while removing the lease possible material, and the least possible alteration to bore shape. 

 

If the bore is worn less than .002" and free of deep scratches that persist after 15 seconds or so of tool time, it can be honed.  If it's over that, it needs to be replated or replaced.

 

Conventional "wisdom" holds that tools like that won't refinish a Nikasil bore because it's so hard....BS.  If you think not, take a piece of ordinary SC sandpaper to a piece of glass once.  See what happens. Just be careful what piece of glass you choose for your test.  The "too hard for brush hones" thing is complete baloney, there's your pictures for proof. 

That Brush and Research place that you mentioned has a 3 3/4 95mm. And a 4 1/8 105mm ball hone in a 240 grit silicon carbide but not just a 97mm one.

So by going by what you said..... I would get the 105mm one ....correct?

97mm Falls between the 95mm hone and the 105mm hone.....so I would get the next up in size from 97mm .......correct?

Just seems like the 105mm is a big jump in size from a 95mm ball hone.

Guess a 95mm hone is a tad to small.

I did finally find a 101mm ball hone by Brush research in 240 grit silicon carbide at this one place for $55.00. Would this be the one you would get and also a Quart of Hone oil?

I appreciate your help Grayracer.

At 85 hours I would do the timing chain but not the top end. These Yamahas are good for at least 150+ hours. Keep riding and save the parts for next season or two if I were you.

 

But I understand it is your bike

The 101mm SC hone should be OK.  You don't need their oil, though.  Any light oil or shop solvent will work.  Wash THOROUGHLY with soap/water and wipe down the bore with a clean, lint free cloth and ATF or light oil. 

 

Use a low speed drill and run the tool up and down the bore rapidly as it spins to produce the cross pattern.  Hone for 4 seconds and check the bore. Repeat if necessary.  Quit as soon as the surface is free of "shadows",  12 -15 seconds total time max. 

At 85 hours I would do the timing chain but not the top end. These Yamahas are good for at least 150+ hours. Keep riding and save the parts for next season or two if I were you.

But I understand it is your bike

.

I might just do that. However I might go ahead and put the chain in. You say these yamaha's are good for about 150 hours........is that the same for the valves? Meaning is the valves worn out by then also an will need replaced along with the piston/rings?

The 101mm SC hone should be OK. You don't need their oil, though. Any light oil or shop solvent will work. Wash THOROUGHLY with soap/water and wipe down the bore with a clean, lint free cloth and ATF or light oil.

Use a low speed drill and run the tool up and down the bore rapidly as it spins to produce the cross pattern. Hone for 4 seconds and check the bore. Repeat if necessary. Quit as soon as the surface is free of "shadows", 12 -15 seconds total time max.

I will go ahead an order me one so I will have one on hand when I do redo the Top End. Thanks for ya help.

I have 120 hours on my 11 on the stock piston.  I will replace it at 150-175 probably.  All my valves are in spec and have never needed attention just like the other 3 YZ450s I have owned.

 

I usually sell the bikes with 2-300ish hours on them.  The 2 I still am aware that I sold now have over 300 hours on the stock valves.

I have 120 hours on my 11 on the stock piston.  I will replace it at 150-175 probably.  All my valves are in spec and have never needed attention just like the other 3 YZ450s I have owned.

 

I usually sell the bikes with 2-300ish hours on them.  The 2 I still am aware that I sold now have over 300 hours on the stock valves.

 

That is some good info. Guess I will just put the new parts up in the cabinet and just wait till after next year to do it.  

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