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Old 01-11-2012, 06:36 PM   #58921
Adv Grifter
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Quote:
Originally Posted by BergDonk View Post
A heavier rider with soft suspension will typically load the suspension past the point of maximum tension, and then it gets looser. If the spring is right and the sag is set, then the rider weight has NO effect on tension.

I reckon you are perpetuating a myth, but I do reserve the right to be wrong

Steve
How many riders do you see who are running their chain too tight? I see plenty ... and I see so called "expert" mechanics releasing bikes back to customers with chain set too tight.

A light weight rider running proper preload and after market spring may not pass through the tight zone all that often ... so may get away without screwing things up ... you know ...
like hubb and wheel bearings!

The heavy rider will for sure. Once he sits on the bike ... the chain is approaching it's tightest point ... and as he rides and hits bumps, he will for sure run the suspension through the half way tight spot ... and in this case ... too tight. I've seen this many times ... and many times on bikes fresh out of the shop.

Inproper preload, sag, spring and chain slack. Ideally ... ALL should be set for individual rider: Enduro 101.
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Old 01-11-2012, 06:39 PM   #58922
Albie
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Originally Posted by Dravintoad View Post
Albie, I know for a fact that has to do with your right hand only having an on/off position. Heavy on the ON.

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Old 01-11-2012, 06:46 PM   #58923
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Quote:
Originally Posted by Adv Grifter View Post
So, you're saying a heavy rider on board, compressing the suspension, has NO AFFECT on chain tension?
Nope, what he's saying is a larger rider has no EFFECT on chain tension.
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Old 01-11-2012, 07:52 PM   #58924
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Quote:
Originally Posted by Adv Grifter View Post
A light weight rider running proper preload and after market spring may not pass through the tight zone all that often ... so may get away without screwing things up.
Nope. If the lighter rider has his suspension set up correctly he will pass through the 'tight zone' just as often as a heavy rider who also has his suspension set up properly.

Once the bike and rider compresses the suspension to the 'race sag' point the wheel only has to compress another 3" or so to get the chain at its tightest point. To avoid that the bike would have to be only ridden mildly on very smooth roads. But even in that case it would not matter if the rider was light or heavy if both riders are running proper preload and after market spring.
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Old 01-11-2012, 08:02 PM   #58925
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Ditto what ProCycle is saying. Either way, if the bike is set up properly for either rider it'll move through the suspension range; otherwise, it wouldn't be set up properly for either rider. It's set up wrong if the lighter rider isn't having the suspension cycle through the range, just as it's too soft (or whatever) if it's on the other end of the spectrum for the heavier rider. It needs to be "tuned" to the rider to work properly, and in that case it's cycling through it's range either way.
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Old 01-11-2012, 08:57 PM   #58926
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Quote:
Originally Posted by JagLite View Post
I bought a nice new Yamaha R6 throttle tube as recommended by several riders.
It decreases the rotation required to go to full throttle.
I only was able to try it on a couple rides before winter arrived with lots of snow but I was pleased with the improvement.

However, while reinstalling my carb after doing the Procycle jet kit, I discovered the "quick throttle" does NOT open the carb fully. I mean that when the cable is tight I can still rotate the cam another 1/4" or so. Yes, the other (close) cable is loose, it is not stopping the throttle.

My guess is that I need to file away some of the plastic on the throttle tube that acts as the stop so that it will rotated more.

Has anyone else noticed this or have this problem? I don't remember reading of it before.
I was able to just adjust the cables up top and at the carb to get a full throw.

Initially it was held open on mine with WOT no problem. Would have made a very fast idle being an 1/8" above the idle screw.
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Old 01-11-2012, 09:23 PM   #58927
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Quote:
Originally Posted by procycle View Post
Nope. If the lighter rider has his suspension set up correctly he will pass through the 'tight zone' just as often as a heavy rider who also has his suspension set up properly.

Once the bike and rider compresses the suspension to the 'race sag' point the wheel only has to compress another 3" or so to get the chain at its tightest point. To avoid that the bike would have to be only ridden mildly on very smooth roads. But even in that case it would not matter if the rider was light or heavy if both riders are running proper preload and after market spring.
Exactly right ... but your missing my point. I'm talking about a heavy rider on a bike NOT set up for his weight. AS IN: the 300 lb. rider in question here on stock suspension. Add to this a chain adjusted a bit snug at a standstill (no rider on bike ... a mistake many make) then he rides off, never realizing how tight the chain gets as it goes through it's travel.
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Old 01-11-2012, 09:43 PM   #58928
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Rev limiter

Is there any way of altering, raising or even removing the rev limiter? I'm not interested in whether it's a sane thing to do, just whether I can do it!
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Old 01-11-2012, 09:50 PM   #58929
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There's a remapped ecm included, in ProCycle's dohc upgrade kit, kinda pricey though...

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Old 01-11-2012, 09:52 PM   #58930
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Quote:
Originally Posted by Adv Grifter View Post
Exactly right ... but your missing my point. I'm talking about a heavy rider on a bike NOT set up for his weight. AS IN: the 300 lb. rider in question here on stock suspension. Add to this a chain adjusted a bit snug at a standstill (no rider on bike ... a mistake many make) then he rides off, never realizing how tight the chain gets as it goes through it's travel.
Actually I get your point but I don't think you are correct.
But you are missing my point. A light rider on a bike set up the same way - stock suspension and too tight chain - will still push through the 'tight zone' of the chain geometry. It doesn't matter what the rider weighs. The heavy rider will just push the suspension further past the tight zone on into the loose chain zone approaching full compression.

That point where the chain is tightest is right around 5" of travel. That's about half way through the 10" of DR suspension travel. Only the very lightest most timid rider would only use 4" of rear suspension travel. Now if that tight point was at 8" of travel you would be correct - but that is not the case.
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Old 01-11-2012, 10:03 PM   #58931
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Quote:
Originally Posted by Adv Grifter View Post
Exactly right ... but your missing my point. I'm talking about a heavy rider on a bike NOT set up for his weight. AS IN: the 300 lb. rider in question here on stock suspension. Add to this a chain adjusted a bit snug at a standstill (no rider on bike ... a mistake many make) then he rides off, never realizing how tight the chain gets as it goes through it's travel.
It doesn't matter if the rider is heavy or light. It doesn't matter if the suspension is properly set up for the riders weight or not. If the chain is too tight for a particular rider, it's too tight for all riders. If the chain is too loose for a particular rider, it's too loose for all riders. Rider weight and bike setup are not variables that have anything to do with proper chain tension. The proper chain tension is a function of the static geometry of the arc of the swingarm and it's relationship to the distance between the axle and drive shaft.
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Old 01-11-2012, 11:58 PM   #58932
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Quote:
Originally Posted by Adv Grifter View Post
How many riders do you see who are running their chain too tight? I see plenty ... and I see so called "expert" mechanics releasing bikes back to customers with chain set too tight.
.
I've seen plenty. A recent example was on a Husky that had not long had its first service at the dealer so as to maintain the 24 mth warranty. I first noticed the issue when the chain actually broke on a trail ride. Luckily for us all I carry some master links and a bit of spare chain, and a breaker.

I've found over the years that people that routinely adjust their chains are routinely over tightening them. Modern chains are amazing things and rarely need tightening if properly maintained. And the need for tightening implies wear.

Quote:
Originally Posted by 955616846 View Post
FWIW...

There are a bunch of variables missing from that diagram when discussing a bike with long travel suspension... Upper and lower rollers, the swing arm slider, the fixed rear chain guide and different sprocket sizes (and how they affect otherwise fixed geometry) seem to be completely ignored. Any interaction between the chain through the suspension travel and these unmentioned variables (one is guaranteed) is going to effectively increase tension / reduce slack at that point in the suspension travel and the only way to know for certain where the chains tightest point is and the affect of those other variables is through detailed analysis or by measurement while compressing the suspension through its entire travel.

Maybe the interactions are not strong enough to have a significant affect so the straight line holds true for the DR, but has anyone here tested it properly?
The variables you note are valid, but mostly only come into play at the extremes of travel, not around 40-60% of travel where tension is greatest. As mentioned above, the rollers' purpose is to keep some tension on the chain as its tension loosens at the travel extremes. Sprocket size affects the leverage the chain pull applies so influences squat. The chain guide shouldn't make any difference, shouldn't..... And the chain sliders are about not gouging holes in the swingarm. In fact I recall years ago you could get aftermarket idler sprockets that clamped on the the swingarm on top and bottom of the pivot. the idea was to eliminate chain tension variations, I think. Back then there was often a big distance between the cs and sa pivot, but not such a big deal with limited suspension travel.

Steve
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Old 01-12-2012, 12:04 AM   #58933
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My advice for those unwilling to sift through all the semantic nuance in here is to run your chain on the loose side. It's easier to replace chain and sprockets than bearings.
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Old 01-12-2012, 12:07 AM   #58934
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Originally Posted by Klay View Post
My advice for those unwilling to sift through all the semantic nuance in here is to run your chain on the loose side. It's easier to replace chain and sprockets than bearings.
But not too loose
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Old 01-12-2012, 12:29 AM   #58935
Phreaky Phil
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Quote:
Originally Posted by Klay View Post
My advice for those unwilling to sift through all the semantic nuance in here is to run your chain on the loose side. It's easier to replace chain and sprockets than bearings.
I can feel when the chain is starting to get loose on my DR. It gets a bit vibby. It may be the under side of the chain touching the chain guide at the rear sprocket. Not really sure.
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