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Old 05-08-2013, 01:21 PM   #58441
mrfixit54016
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Quote:
Originally Posted by boboneleg View Post
So I finally got around to stripping the head off my (new to me) bike to find out what is making the 'clacking' sound.

Here is the camchain tensioner, does the spring look right to you as it looks like the end may have snapped off?



There are also some marks inside the head where it mounts.....



Could this be the source of the 'clacking' sound?

The other thing is the head gasket seems to be a 'triple' or is this three head gaskets together?



Sorry the photo is not too clear but it was hard to show it clearly.

Bob.
Bob,

It looks like you need a new tensioner, that spring end is probably floating around in your engine somewhere. Do not forget to order the new O-ring for the tensioner either. It will keep you from cussing yourself out when the re-assembled engine starts weeping oil around the tensioner because you decided to save $4.00 and skip the O-ring...

That head gasket just looks like a multi-ply gasket to me. Order a new OEM Honda gasket to re-assemble the engine. The top cover gasket can probably be re-used if it is the metal OEM gasket.

Good Luck.
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Old 05-08-2013, 01:32 PM   #58442
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[QUOTE=boboneleg;21361701]









QUOTE]


Was the bolt that goes through the tensioner shaft in place? It looks like the spring end straightened out and slipped up the side of the head thus no longet exerting tension on the tensioner.

The head gasket is multi layer.
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Old 05-08-2013, 01:39 PM   #58443
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BobOneLeg: That tensioner end is snapped off. Good job discovering that. Hey when it comes to reassembly, watch the YouTube video of the guy with the Zip Tie trick. It works fantastic. I've used it a couple times now.

ZuluSafari: Regarding the sit or stand, that's a no-brainer - Anyone would ALWAYS say STAND, and let your knees absorb some of the impact instead of your spine. I'm not saying stand all the time, just when you see bumps.

They also say, when in doubt, throttle out!

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Old 05-08-2013, 02:06 PM   #58444
zulusafari
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Quote:
Originally Posted by mcma111 View Post
The real lesson learned is to not follow so closely to the vehicle in front of you.

The NX fifth gear would be an option to dropping the revs and having the engine run cooler. If you were to revert to the OE 15/45 gearing the OE motor doesn't have enough ommph to pull fifth. To install the fifth gear requires a complete engine tear down.
Indeed, I guess I assumed that was obvious enough. I was passing a lot b/c all the heavy trucks are pretty slow on the hilly roads around Nairobi, so I think I was readying a pass, but honestly don't recall much of what happened before my near miss.

Yeah, I'm aware of the complete teardown. I am asking a trusted local wrench what he would charge to do it for me. That's why I mentioned I might go ahead and do the 2nd gear and kick start as well. I assume those would be small expenses since the whole engine is appart. Thanks for the tip on the original sprockets not being able to handle the NX 5th gear. Good to take into account.
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Old 05-08-2013, 02:15 PM   #58445
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Quote:
Originally Posted by Brown Falcon View Post
I would say standing is better. Absorb more impact, not get bounced off the seat.
Forgot to mention that. I was thinking that the hit would be so hard it would literally throw me from the bike.

Quote:
Originally Posted by kenny61 View Post
Rumor has it standing will actually lower the center of gravity. I would stand if any large obstruction was in my way
Quote:
Originally Posted by Spud Rider View Post
However, if the drop into a hole is unavoidable, I would stand. Standing does lower the center of gravity as your body weight is transferred from the saddle to the foot pegs. Also, you can use your legs and knees to absorb the shock of impact while you are standing.

Spud
Quote:
Originally Posted by techforlife View Post
+1 Stand up..better control too..
B
Thanks gents. Interesting to learn that the center of gravity is lowered when you stand. Spud's explanation makes perfect sense... mostly. If you hold a 45lb weight over your head and then hold it at your knees, which feels more stable? They are both connected at your shoulder. All things being equal, the location of the weight itself is what's important. I think there's two factors at play there. Maybe they offset to some degree. I am happy I stayed with wider handle bars, for control in a situation like that... that I had not planned.
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zulusafari screwed with this post 05-08-2013 at 02:25 PM
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Old 05-08-2013, 05:04 PM   #58446
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Curse he who invoked the pedantic fuck in me...

From a physics point of view standing absolutely does not lower the center of gravity of the bike-rider system.

Standing actually raises the CG of the bike-rider combined system- but, that is actually the less important part of the story.

Standing does however allow more decoupling of the bike and rider, and allows the bike and rider to behave somewhat independently.

Think of a bike and rider as a 2 weights rubber-banded together, one on top of another. CG is wherever, somewhere between the CG of the bottom block and the upper block.
Now imagine the top weight is supported above the lower weight by stalks- the lower weight CG is in the same place, the upper weight CG has moved up, so the combined CG must also have moved up.

Now, imagine those stalks are not stiff, but are damped springs. The lower weight can move up and down to a degree with the upper weight not moving. That's what it's like when you stand.

Subject to how the bike can react, to a limited degree, you could say the bike has it's own CG and the rider his own CG, and life is pretty good as long as the rider can keep his CG generally over the bike, and keep his velocity vector aligned with the bikes.

The bike having 'its own' cg means it is operating with a lower CG, hence saying standing lowers the CG is somewhat right whilst also being horribly wrong.

I'll really stir the pot by saying if you stand on the pegs evenly, or stand with all your weight on only one peg, there is absolutely no change in the CG of the bike, the rider, or the combined system. Weighting the pegs in a turn has no effect on CG whatsoever.



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Old 05-08-2013, 05:19 PM   #58447
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Quote:
Originally Posted by XR650L_Dave View Post
Curse he who invoked the pedantic fuck in me...

From a physics point of view standing absolutely does not lower the center of gravity of the bike-rider system.

Standing actually raises the CG of the bike-rider combined system- but, that is actually the less important part of the story.

Standing does however allow more decoupling of the bike and rider, and allows the bike and rider to behave somewhat independently.

Think of a bike and rider as a 2 weights rubber-banded together, one on top of another. CG is wherever, somewhere between the CG of the bottom block and the upper block.
Now imagine the top weight is supported above the lower weight by stalks- the lower weight CG is in the same place, the upper weight CG has moved up, so the combined CG must also have moved up.

Now, imagine those stalks are not stiff, but are damped springs. The lower weight can move up and down to a degree with the upper weight not moving. That's what it's like when you stand.

Subject to how the bike can react, to a limited degree, you could say the bike has it's own CG and the rider his own CG, and life is pretty good as long as the rider can keep his CG generally over the bike, and keep his velocity vector aligned with the bikes.

The bike having 'its own' cg means it is operating with a lower CG, hence saying standing lowers the CG is somewhat right whilst also being horribly wrong.

I'll really stir the pot by saying if you stand on the pegs evenly, or stand with all your weight on only one peg, there is absolutely no change in the CG of the bike, the rider, or the combined system. Weighting the pegs in a turn has no effect on CG whatsoever.



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you smart people confuse me. but.............. ima go with standing up is better when hitting a hole; whether on a bike or..........
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Old 05-08-2013, 05:23 PM   #58448
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Quote:
Originally Posted by XR650L_Dave View Post
Curse he who invoked the pedantic fuck in me...

From a physics point of view standing absolutely does not lower the center of gravity of the bike-rider system.

Standing actually raises the CG of the bike-rider combined system- but, that is actually the less important part of the story.

Standing does however allow more decoupling of the bike and rider, and allows the bike and rider to behave somewhat independently.

Think of a bike and rider as a 2 weights rubber-banded together, one on top of another. CG is wherever, somewhere between the CG of the bottom block and the upper block.
Now imagine the top weight is supported above the lower weight by stalks- the lower weight CG is in the same place, the upper weight CG has moved up, so the combined CG must also have moved up.

Now, imagine those stalks are not stiff, but are damped springs. The lower weight can move up and down to a degree with the upper weight not moving. That's what it's like when you stand.

Subject to how the bike can react, to a limited degree, you could say the bike has it's own CG and the rider his own CG, and life is pretty good as long as the rider can keep his CG generally over the bike, and keep his velocity vector aligned with the bikes.

The bike having 'its own' cg means it is operating with a lower CG, hence saying standing lowers the CG is somewhat right whilst also being horribly wrong.

I'll really stir the pot by saying if you stand on the pegs evenly, or stand with all your weight on only one peg, there is absolutely no change in the CG of the bike, the rider, or the combined system. Weighting the pegs in a turn has no effect on CG whatsoever.



This message brought to you by the society of grouchy pedants, dedicated to bringing technically true but usually useless information to the public since 1973.
awesome post and I agree, Ill just add that by standing what you do is like you say decouple you and the bike, and the bike for better or worse is freer to do what it wants...the xr likes to be ridded this way, point and shoot and it will not go straight but in the end you will get to point B.

excellent post...
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Old 05-08-2013, 05:26 PM   #58449
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The last time I hit a hole was almost three years ago. Fifteen MPH on the BMW R100gs. Yes, it still hurts.

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Old 05-08-2013, 05:49 PM   #58450
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Quote:
Originally Posted by XR650L_Dave View Post
Curse he who invoked the pedantic fuck in me...

From a physics point of view standing absolutely does not lower the center of gravity of the bike-rider system.

Standing actually raises the CG of the bike-rider combined system- but, that is actually the less important part of the story.

Standing does however allow more decoupling of the bike and rider, and allows the bike and rider to behave somewhat independently.

Think of a bike and rider as a 2 weights rubber-banded together, one on top of another. CG is wherever, somewhere between the CG of the bottom block and the upper block.
Now imagine the top weight is supported above the lower weight by stalks- the lower weight CG is in the same place, the upper weight CG has moved up, so the combined CG must also have moved up.

Now, imagine those stalks are not stiff, but are damped springs. The lower weight can move up and down to a degree with the upper weight not moving. That's what it's like when you stand.

Subject to how the bike can react, to a limited degree, you could say the bike has it's own CG and the rider his own CG, and life is pretty good as long as the rider can keep his CG generally over the bike, and keep his velocity vector aligned with the bikes.

The bike having 'its own' cg means it is operating with a lower CG, hence saying standing lowers the CG is somewhat right whilst also being horribly wrong.

I'll really stir the pot by saying if you stand on the pegs evenly, or stand with all your weight on only one peg, there is absolutely no change in the CG of the bike, the rider, or the combined system. Weighting the pegs in a turn has no effect on CG whatsoever.



This message brought to you by the society of grouchy pedants, dedicated to bringing technically true but usually useless information to the public since 1973.
Thank you for finally breaking your silence on this issue. I, too, have gritted my teeth whenever the claim is made.

I find it totally true that standing results in superior stability and reduced risk of get-offs/yard sales but as you so eloquently point out, doing so DOES NOT lower any centers of mass - in fact it only raises them. I agree, standing separates person from machine, allowing independent jockeying and shock absorption. It also allows the bike to move with less linear and rotational inertia, as you are no longer attached to it rigidly. This means it can move and rotate quicker as the trail rises, falls, and changes direction. The analogy of two weights connected by rubber bands is quite good. The weights can move and twist faster individually than if they were glued together.

I will always recommend standing to any dirt biker or mountain biker, but whomever says that it lowers COG is making a false assumption or disseminating bad BS.

Back to our regularly scheduled program...
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Old 05-08-2013, 05:49 PM   #58451
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I wondered if standing really would lower the CG... seemed odd, but I am too damned dumb to mount an intelligent argument on the topic. You know what they say... keep your mouth shut and let them think you a fool... open your mouth and remove any doubt
Quote:
Originally Posted by XR650L_Dave View Post
Curse he who invoked the pedantic fuck in me...

From a physics point of view standing absolutely does not lower the center of gravity of the bike-rider system.

Standing actually raises the CG of the bike-rider combined system- but, that is actually the less important part of the story.

Standing does however allow more decoupling of the bike and rider, and allows the bike and rider to behave somewhat independently.

Think of a bike and rider as a 2 weights rubber-banded together, one on top of another. CG is wherever, somewhere between the CG of the bottom block and the upper block.
Now imagine the top weight is supported above the lower weight by stalks- the lower weight CG is in the same place, the upper weight CG has moved up, so the combined CG must also have moved up.

Now, imagine those stalks are not stiff, but are damped springs. The lower weight can move up and down to a degree with the upper weight not moving. That's what it's like when you stand.

Subject to how the bike can react, to a limited degree, you could say the bike has it's own CG and the rider his own CG, and life is pretty good as long as the rider can keep his CG generally over the bike, and keep his velocity vector aligned with the bikes.

The bike having 'its own' cg means it is operating with a lower CG, hence saying standing lowers the CG is somewhat right whilst also being horribly wrong.

I'll really stir the pot by saying if you stand on the pegs evenly, or stand with all your weight on only one peg, there is absolutely no change in the CG of the bike, the rider, or the combined system. Weighting the pegs in a turn has no effect on CG whatsoever.



This message brought to you by the society of grouchy pedants, dedicated to bringing technically true but usually useless information to the public since 1973.
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Originally Posted by Cigar Mike :With plastic buy two.
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Old 05-08-2013, 06:04 PM   #58452
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Would there be a decoupling?

Quote:
Originally Posted by Pucker View Post
Thank you for finally breaking your silence on this issue. I, too, have gritted my teeth whenever the claim is made.

I find it totally true that standing results in superior stability and reduced risk of get-offs/yard sales but as you so eloquently point out, doing so DOES NOT lower any centers of mass - in fact it only raises them. I agree, standing separates person from machine, allowing independent jockeying and shock absorption. It also allows the bike to move with less linear and rotational inertia, as you are no longer attached to it rigidly. This means it can move and rotate quicker as the trail rises, falls, and changes direction. The analogy of two weights connected by rubber bands is quite good. The weights can move and twist faster individually than if they were glued together.

I will always recommend standing to any dirt biker or mountain biker, but whomever says that it lowers COG is making a false assumption or disseminating bad BS.

Back to our regularly scheduled program...
But when you hit the pot hole, and your legs and arms flexed allowing your body to maintain inertia independent of the bike would you, in effect, decouple your body mass for an instant and effectively lower the COG in that moment?
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Old 05-08-2013, 06:39 PM   #58453
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Quote:
Originally Posted by Deliverator View Post
But when you hit the pot hole, and your legs and arms flexed allowing your body to maintain inertia independent of the bike would you, in effect, decouple your body mass for an instant and effectively lower the COG in that moment?
Your body mass would not lower, any more than it would move to the side in a car making sharp turn. Your body mass would follow Newton's first law - continuing in with constant velocity while the ground (and partially independent bike below you) changed. The bike would lower its center of mass (momentarily) and raise it back up much quicker without you attached. That's they beauty of separating the two sub-systems and connecting them with elastic links (your arms and legs) - they can each move more easily by themselves and lessen the impulses (forces over time) exerted each other. Make no mistake - you WILL feel the forces exerted by the bike, but standing allows you to spread the forces over longer and more manageable durations.
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Old 05-08-2013, 07:05 PM   #58454
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Quote:
Originally Posted by Pucker View Post
Your body mass would not lower, any more than it would move to the side in a car making sharp turn. Your body mass would follow Newton's first law - continuing in with constant velocity while the ground (and partially independent bike below you) changed. The bike would lower its center of mass (momentarily) and raise it back up much quicker without you attached. That's they beauty of separating the two sub-systems and connecting them with elastic links (your arms and legs) - they can each move more easily by themselves and lessen the impulses (forces over time) exerted each other. Make no mistake - you WILL feel the forces exerted by the bike, but standing allows you to spread the forces over longer and more manageable durations.
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Originally Posted by Cigar Mike :With plastic buy two.
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Old 05-08-2013, 07:39 PM   #58455
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I knew that post would get the page rolling
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