17.5 hours on 2014 YZ450F, about to check/adjust valves, any tips?


14 replies to this topic
  • GHILL28

Posted March 10, 2015 - 07:38 AM

#1

I'm noticing just a little bit less ease of hot starting on my YZF, so it's time to check the valves and see what they're doing.  Done plenty of valve adjustments on various 4-strokes, so that part isn't a problem.  It's mostly the EFI and fuel tank stuff that I'm not experienced with yet.  This is my first EFI bike.  Running Mobil 4 Racing 4T oil, Scotts SS filter, oil changed 3 times now, clean air filter every ride, lately been running 50/50 AV gas.

 

I have the IMS tank on mine, which means a total mission of removing the subframe and silencer as well, so I'd prefer to just do this once, and any tips to avoid making a complete mess would be appreciated.

 

Do I HAVE to disconnect the fuel line to access the valve cover?  

If I disconnect it, how does this system prime after re-connecting?  

Anything else weird to be aware of in terms of access?  

Can the tank be drained from the bottom/fuel pump easily?  

 

Does the header pipe have to come off to access the chain tensioner?

At this point are there any other good-practice maintenance items to do while I'm in there?  

Anything with the throttle body or fuel pump or injection system?

 

Thanks in advance.



  • grayracer513

Posted March 10, 2015 - 08:21 AM

#2

The fuel system "primes" by cranking the engine (generating current to operate the pump).  Really nothing more to it except it may take a few extra turns of the crank to start it for the first time while it forces the air from the fuel line. 



  • GHILL28

Posted March 10, 2015 - 08:42 AM

#3

So it's fine putting air through the injector on the first few cycles?  I guess it won't fire until it primes completely of air and gets adequate fuel running into the intake.



  • grayracer513

Posted March 10, 2015 - 08:52 AM

#4

Unless you hold the throttle open beyond half to 3/4 open (which, at starting speeds, causes the fuel injector to be commanded "off" to clear floods), the injector will get a PWM signal opening and closing it as if fuel were there.  Trapped air escapes the fuel line past the injector remarkably fast under 45 PSI of pressure that way, so it doesn't take too long to clear it.



  • Phil Hannah

Posted March 10, 2015 - 03:29 PM

#5

I'm noticing just a little bit less ease of hot starting on my YZF, so it's time to check the valves and see what they're doing.  Done plenty of valve adjustments on various 4-strokes, so that part isn't a problem.  It's mostly the EFI and fuel tank stuff that I'm not experienced with yet.  This is my first EFI bike.  Running Mobil 4 Racing 4T oil, Scotts SS filter, oil changed 3 times now, clean air filter every ride, lately been running 50/50 AV gas.
 
I have the IMS tank on mine, which means a total mission of removing the subframe and silencer as well, so I'd prefer to just do this once, and any tips to avoid making a complete mess would be appreciated.
 
Do I HAVE to disconnect the fuel line to access the valve cover?  
If I disconnect it, how does this system prime after re-connecting?  
Anything else weird to be aware of in terms of access?  
Can the tank be drained from the bottom/fuel pump easily?  
 
Does the header pipe have to come off to access the chain tensioner?
At this point are there any other good-practice maintenance items to do while I'm in there?  
Anything with the throttle body or fuel pump or injection system?
 
Thanks in advance. Could AV gas have anything to do with starting a tad hard when hot?



  • GHILL28

Posted March 10, 2015 - 03:37 PM

#6

Really not sure about the AV gas.  I can't imagine why it would, but I'm open to explanations/ideas.

 

What I've heard from Yamaha guys is that the stock compression on this bike is closer to 13:1 and not 12.5:1, so the AV gas should help with the stock lean condition.  Also my fuel range was lower than idea with the richer mapping I had put in to compensate, so the AV gas with a leaner map seemed to be a good balance.



  • GHILL28

Posted March 10, 2015 - 07:15 PM

#7

All valves are on the very tight side of acceptable range.  

 

.005" and .006" for intakes.  Spec is .005"-.008".

 

.008" for exhausts.  Spec is .008"-.010".

 

Shim or no shim?

 

Am I correct in assuming 175 shims are what these bikes are delivered with stock at each valve?  The manual would lead me to believe so but I haven't taken the cams out to verify.



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  • grayracer513

Posted March 11, 2015 - 06:26 AM

#8

What I've heard from Yamaha guys is that the stock compression on this bike is closer to 13:1 and not 12.5:1, so the AV gas should help with the stock lean condition.

AV Gas does not run any richer/leaner per volume, and the increased octane or lead content won't affect the A/F ratio, either, so I don't get what you think you mean.



  • GHILL28

Posted March 11, 2015 - 06:27 AM

#9

Just to get rid of any popping associated with the stock (or closer to stock) mapping. The MXA map that's popular for these was hog rich. Could smell the gas far away from the bike.

  • yzUSMCf

Posted March 20, 2015 - 06:04 PM

#10

I've got 43 hrs on my bike and valves are about middle in the tolerance range. Haven't had to adjust them yet.

  • GHILL28

Posted December 21, 2015 - 11:24 AM

#11

Update:  45 hours on bike, valves are still in the exact same spot.  That's good I think.



  • yzUSMCf

Posted December 21, 2015 - 03:10 PM

#12

Im at 70h haven't needed to adjust them.

  • Wiz636

Posted December 22, 2015 - 08:20 PM

#13

At 400+ hours on my '08 the valves were still in spec.

 

Every YZ I've bought new had the valves set in the low end of the tolerance from the factory.



  • ckny

Posted December 25, 2015 - 10:57 AM

#14

I know lots of guys not shimming valves until 100 hours on that motor.

  • luckyguy19

Posted December 25, 2015 - 08:13 PM

#15

120 hours on mine, still not moved. 







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