 Valve clearance
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Joined: Jan 2005
Posts: 122
Adjunct
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OP
Adjunct
Joined: Jan 2005
Posts: 122 |
Hello,
According to the manual the valve clearance for the TBA intake valve (cold engine) should be 0.15 - 0.20 mm
At both cylinders I get 1 intake valve 'go' at 0.10 and 'no go' at 0.15 and 1 intake valve with 'go at 0.20 and 'no go' at 0.25. To me this seams that I have 2 valves slightly below spec and two slightly above spec.
So now I am wondering if this is something that I should try to correct asap or if it is liveable at the moment. Second question is if I correct it should I aim on the low side or the high side?
Thanks for any inputs
Regards
Hasse
Hasse TBA -02 Pre-Fire Cardinal Red, Wiseco 904, Thunderbike pipes, Freak
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Re: Valve clearance
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Joined: Jan 2005
Posts: 9,223
Big Bore
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Big Bore
Joined: Jan 2005
Posts: 9,223 |
I would advise not to use a go/no go scenario. You should find the exact gap and proceed from there. Stack the blades up as needed to get an exact gap. Hopefully, you are using a true metric feeler gauge? Are you planning on doing the work yourself? Personally, I would not let that tight one sit, nor the really loose one. You might get lucky though in that you could swap those two. My first valve job, I was able to swap my only two out of spec shims and bring both to the middle of the tolerance range. I always try to get the gap as close to the middle of the range as possible but looser is better. I also highly recommend getting Dinqua's Shim Calculator. An invaluable tool when figuring out what shims you need.
"Never underestimate the power of human stupidity" - Robert Heinlein
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Re: Valve clearance
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Joined: Jan 2005
Posts: 4,931 Likes: 1
Loquacious
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Loquacious
Joined: Jan 2005
Posts: 4,931 Likes: 1 |
hmmm..you are supposed to check your valves?? 20k miles & mine still chatter like new.
we should do this every weekend!
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Re: Valve clearance
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Joined: Feb 2007
Posts: 23,194 Likes: 56
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,194 Likes: 56 |
Yota you are taking a chance there. If you have a valve not closing all the way it can erode the seat and valve making it much more costly when you do get it done. I have heard of guys valves getting tighter as opposed to looser and if they get tight enough not to close all the way you have compression leakage as well robbing performance.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: Valve clearance
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Joined: Jan 2005
Posts: 1,335
Learned Hand
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Learned Hand
Joined: Jan 2005
Posts: 1,335 |
Hans,
Everything Phil said is good. I will add that when I did my first check and adjustment I had one intake valve clearance that was smaller than 0.04mm, how much smaller I don't know since my feeler gauge only went down to 0.04mm. After adjusting everything I really couldn't tell any difference. So I don't think you have to worry about damaging anything, but I would do the adjustment at the earliest opportunity.
Tom
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.
Benjamin Franklin, US author, diplomat, inventor, physicist, politician, & printer (1706 - 1790)
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Re: Valve clearance
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Joined: Aug 2005
Posts: 2,726
Loquacious
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Loquacious
Joined: Aug 2005
Posts: 2,726 |
Quote:
hmmm..you are supposed to check your valves?? 20k miles & mine still chatter like new.
I had my dealer check my valves at the 2 year service (9000 miles) and 6 of the 8 valves needed shims. They said it was probably off a bit from the factory as they don't take as much time adjusting each bike. I'm glad I had them do the check. The service chart says 2 years or 12000 miles, whichever comes first. The dealer said they don't usually do it until 12000.
Bob
2005 America, 904cc - sold. 2014 Trophy SE.
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Re: Valve clearance
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Joined: Jan 2005
Posts: 2,297
Oil Expert
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Oil Expert
Joined: Jan 2005
Posts: 2,297 |
Quote:
Quote:
hmmm..you are supposed to check your valves?? 20k miles & mine still chatter like new.
I had my dealer check my valves at the 2 year service (9000 miles) and 6 of the 8 valves needed shims. They said it was probably off a bit from the factory as they don't take as much time adjusting each bike. I'm glad I had them do the check. The service chart says 2 years or 12000 miles, whichever comes first. The dealer said they don't usually do it until 12000.
Obviously, this will no longer be a problem in North Georgia as Chy takes the reigns. We should all go there. Not just in May, every weekend. 
In Between the Dark and the Light..
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Re: Valve clearance
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Joined: Apr 2005
Posts: 3
Complete Newb
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Complete Newb
Joined: Apr 2005
Posts: 3 |
Where do you get the shims?
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Re: Valve clearance
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
Quote:
Where do you get the shims?
Here's one place.
The other is your local Yamaha dealership.
There's much more info in the Tech Vault.
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Re: Valve clearance
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Joined: Apr 2007
Posts: 3,059 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,059 Likes: 8 |
Quote:
After adjusting everything I really couldn't tell any difference. So I don't think you have to worry about damaging anything, but I would do the adjustment at the earliest opportunity.
Agreed - If your engine was running fine before the valve adjustment, you really won't notice any difference in performance.
There is a damage concern though!
Valves that are too loose will create more tappet noise. This usually isn't harmfull unless you have way too much clearance usually caused by a worn cam bearing, lobe, tappet, shim, etc.
Too tight on the clearance will generally give less noise but can be way more damaging. As the valves wear into the valve seats, they move up in the head taking up the clearance in the valve train. If the valves move up so much that they can't close properly, the valve won't be able to transfer heat to the head and burn. Expensive.
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: Valve clearance
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Joined: Jan 2005
Posts: 8,639 Likes: 3
Old Hand
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Old Hand
Joined: Jan 2005
Posts: 8,639 Likes: 3 |
For a preliminary test, use .15 for a go and .20 for a no go. If the .15 is tight or doesn't fit or the .20 is a loose fit, then you should work out a combination that will tell you the exact gap. Use the difference between the exact gap and .175, add or subtract to/from the current shim size (depending on whether the clearance is too small or too large) to determine what shim you need. By the way, if the shim you need is not a size that is made, go with the next thinner one. Too much valve clearance is better than too little.
Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python
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Re: Valve clearance
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Joined: Sep 2007
Posts: 37
Greenhorn
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Greenhorn
Joined: Sep 2007
Posts: 37 |
for what it's worth, I had my valves adjusted at 18648 miles the mechanic said everything look good no wear on enything and looser is better as he statted expesially in hot weather 
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