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Jim Herman

05 WR450F Torquing cam cap bolts?

21 posts in this topic

I'm doing my first valve adjustment and ready to torque the 8mm cap bolts. As the frame drops lower over the back of the motor it leaves less room over the back center bolt. I am using a 3/8 drive torque wrench that won't fit. Any suggestions on tools or technique would be much appreciated.:banana:

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After you torqued some bolts using the torque wrench, get another wrench, a normal wrench, and put it on the already torqued bolts and try to feel, how much has it been tightened, without overtightening it. Now go and tighten the last one(s). It requires some confidence and some feeling in your hands, but can be done. You must know that a loose cap is much worse than an overtightened cap!

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I played with the calculator some and it seems to work like this: If the extension is 10% of the torque wrench length, then the actual torque at the nut increases by 10% over the setting on the wrench. So a 1 inch extension on a 10 inch wrench increases torque by 10%, 2 inch on a 10 inch wrench is a 20% increase, etc.

Pretty neat.

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Also, some pretty smart guys who have a lifetime automotive/tech background from the YZ side (the moderator, to name one), highly recommend lowering the torque value to 70 inch-pounds instead of the 86 inch-pounds in the manual. Been doing this for the past couple of years with no ill effects.

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Thanks much for all the input. First of all it's good to know I'm not the first to be scratching my head over this! This forum works!

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so what did you end up using?

I just did mine by feel,

but I'd like to get a torque wrench in there, someday!

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Also, some pretty smart guys who have a lifetime automotive/tech background from the YZ side (the moderator, to name one), highly recommend lowering the torque value to 70 inch-pounds instead of the 86 inch-pounds in the manual. Been doing this for the past couple of years with no ill effects.

WHat are you referring to that gets 86 ft/lb ?

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WHat are you referring to that gets 86 ft/lb ?

I was referring to the torque spec for the cam cap bolts which in the manual is 86 in-lb. (not 85 ft-lb - that would be strip city!)

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In regard to the torque value on the bolts, I recommend limiting it to 75 in/lb (6.25 ft/lb) rather than the prescribed 86 in/lb (7.2 ft/lb). I also very much recommend that the bolts be drawn up in at least 4 steps (in inch pounds): 10, 45, 60, 75.

NEVER draw the cap down against the head with the bolts. You should be able to press the cap very nearly all the way down with your fingers, and tap it into place with a screwdriver handle.

I use a 1/4", 0-120 in/lb flex beam for these, but they are hard to find anymore. Most 1/4" ratchet torque wrenches will fit. If you use a torque adapter/wrench extension, you can avoid all of the calculations/guesswork by attaching them to the wrench at a right angle, so that it sticks out of the wrench to the side, in an "L" shape. When mounted in this manner, you simply read the torque directly. 75 indicated is 75 actual.

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In regard to the torque value on the bolts, I recommend limiting it to 75 in/lb (6.25 ft/lb) rather than the prescribed 86 in/lb (7.2 ft/lb). I also very much recommend that the bolts be drawn up in at least 4 steps (in inch pounds): 10, 45, 60, 75.

NEVER draw the cap down against the head with the bolts. You should be able to press the cap very nearly all the way down with your fingers, and tap it into place with a screwdriver handle.

I use a 1/4", 0-120 in/lb flex beam for these, but they are hard to find anymore. Most 1/4" ratchet torque wrenches will fit. If you use a torque adapter/wrench extension, you can avoid all of the calculations/guesswork by attaching them to the wrench at a right angle, so that it sticks out of the wrench to the side, in an "L" shape. When mounted in this manner, you simply read the torque directly. 75 indicated is 75 actual.

would something like this be worth the investment for valve checks/etc..?

http://www.sears.com/shc/s/p_10153_12605_00993097000P

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Something like that, yes. I'm only passingly familiar with that brand, but it should be good for a home hobbyist type use. Just a question of whether it clears everything or not.

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Something like that, yes. I'm only passingly familiar with that brand, but it should be good for a home hobbyist type use. Just a question of whether it clears everything or not.

Okay, that's good to hear. It certainly would only be for some light home usage, just the occasional valve adjustment and other small things. That's if it even comes to having to adjust the valves, I've got 2 yamahas; an 07 and an 08, so I might still be far away from needing it. I just want to have it so that when I do check the valves I have it handy if I need it.

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I have a similar 1/4" torque wrench and use it on my WR250F to good effect.

I'd like to see a pic of your torque wrench getting to those center intake bolts. anyone?

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