09 KLX250 Cam Chain
#21
09-20-2010, 11:53 PM
I'm sold,,,,,
Ok, so now that you sold me,,, where do i get a a manual unit???
You asked for it:
"Now to address what I observed before making my first manual tensioner. The rack and pawl design with a spring will constantly put some minimal pressure on the chain slider which would promote wear. The spring isn’t strong enough to resist kickback in the chain under crank deceleration, so it isn’t of any value in tension control in that area. What it does is put enough pressure on the rack to push it forward and the pawl clicks in as the chain seats in and cam drive wear occurs… but not always completely.
The thing I've found interesting in both the KLX and some other forums is the expectation that Kawasaki engineers are infallable and that replacing these tensioner parts and resetting supposedly automatic tensioners would be a normal practice. If it is automatic shouldn't it be automatic? Why should I "reset" or back out until I hear a click, effectively doing a manual tensioning and also making it too tight? I don't buy it. One guy on the KLX site thinks it's okay to replace HyVo chains at 12,000 miles. Those chains are the same design used in some automobiles that run for about a lifetime and on the primary drives of many in-line fours. Other guys think it's okay to back out the mount bolts to effectively override the automatic system.
Now to address what I observed before making my first manual tensioner. The rack and pawl design with a spring will constantly put some minimal pressure on the chain slider which would promote wear. The spring isn't strong enough to resist kickback in the chain under crank deceleration, so it isn't of any value in tension control in that area. What it does is put enough pressure on the rack to push it forward and the pawl clicks in as the chain seats in and cam drive wear occurs… but not always completely.
The key point is that the automatic tensioner clicks in incremental amounts. Cam chains wear/seat dynamically (no increments). When the wear, which by my manual tensioner adjustments has proven to be minimal, isn't enough to move the rack forward forward enough to seat in, but just barely over the tip of the tooth there will be problems. And of course there is no way to tell this. Under cam drive deceleration the rack can kick back hard enough to force the rack back over the pawl, damaging the edges of both by chipping off the edge. This is the same effect as the rounding of shifter dogs when gear boxes are abused with incomplete or missed shifts, but on a much much smaller scale. It takes a magnifier to see the wear (actual rounding), but not the evidence of the wear (polishing of teeth). If this occurs over and over the edges round, much like shifter dogs can, but eventually the rack may start skipping over multiple teeth.
After two of the OEM tensioners in 15,000 miles, the second one costing $70 initially and then about $300 in rebuild costs after it failed, I have no qualms about recommending a manual unit. With simple adjustments on fairly wide intervals after seating in of any new components, the unit is reliable as a rock. I've got 28,000 on my bike with a manual unit, I can't remember now when the last adjustment was made, but it still isn't making any rattling noise except when cold and that is due to play allowed for thermal expansion. I have another rider with a Concours who has 23,000 on his with the same minimal adjustment. Less than one full turn of the adjuster bolt. It is so small a movement if you look at the OEM rack you'll understand why it is possible to have one go bad and another one go without issue. It's just not worth the $70 for the automatic one if it fails again. The manual units are more reliable, the biggest problem with them is when a rider doesn't recognize when it rattles it is time to adjust it.
Now if you adjust the manual tensioner the way I describe it, or another way I learned from the Eliminator owners, you will have taken virtually all the play out of the cam chain drive, but put virtually no tension on it. The OEM automatic tensioner's spring actually does put unneeded tension on the drive all the time, pushing in. All that need be done is take out all the slack, that is ideal.
The play is taken out by either listening for the rattle caused by the loose chain play, which can also be felt if actually doing the turning in by hand. I will tell you I put a socket on my inch/pound torque wrench, held it and twisted as hard as I could... I couldn't even get the beam to deflect. So obviously hand tightening is nearly impossible to overtighten, but I still go by the sound and feel.
Since this is all done at full operating temperature everything is thermally expanded to probably a thousandth or two of maximum growth over all, all inclusive. In other words the drive is as tight as it will get due to expansion. This will result in a very tiny amount of slack when the engine is cold, but that slack is so little it will be inconsequencial as my 28,000 miles show it to be.
As for the chain, again those chains are the same design used in some automobiles that run for about a lifetime and on the primary drives of many in-line fours. They are known for durability when bathed in oil - which they are. Do the research on the internet, I did. I also have never seen a cam chain actually break in the 22 years I spent in a mid-size dealership where I used to love to go hang out in the shop. The one thing I have seen is damage caused by loose cam chains beating up the sliders, variable cam timing as the chain slack allows it to vary by a large amount when the tensioner allows .250 movement when the rack pushes back and forth over 3-4 teeth, and overly worn cam chains from that slapping and snapping around. I will say I did see some Honda ATC200 engines, which use a roller chain, that didn't have the manual adjustment done on them at all, resulting in a lot of chain slap... enough to break the tensioner sliders in them and actually cut through the cylinder cam drive tower area on one. Incredible!
Now the negative on the manual unit. You have to be aware of any ticking coming from the left side cam drive area when it's hot, so you can k ow when to adjust it. That's an actual audible signal that is far quieter than the clatter from a failed OEM automatic tensioner, indicating far less play. It's usually a small adjustment of 1/8-1/4 turn of the adjuster bolt (one full turn is .060" on the M8-1.25 bolt I use) and might only come about every several thousand miles.
You'll actually check your valves more often than it will need adjustment. All you do is every so often at the end of your ride let the bike sit there and run while you take off your helmet and listen on the left side to see if it's ticking at all. Just don't confuse valve tick from the head with chain ticking from the tensioner area. I even got a mechanic's stethoscope to do mine just to be sure. It was more for the Zephyr where the drive is in the center of the engine, the outside cam drives are easy to hear."
This sums up what I've learned over the past ten years from both observation, reading, and my mechanical engineering background. I hope that helps.
"Now to address what I observed before making my first manual tensioner. The rack and pawl design with a spring will constantly put some minimal pressure on the chain slider which would promote wear. The spring isn’t strong enough to resist kickback in the chain under crank deceleration, so it isn’t of any value in tension control in that area. What it does is put enough pressure on the rack to push it forward and the pawl clicks in as the chain seats in and cam drive wear occurs… but not always completely.
The thing I've found interesting in both the KLX and some other forums is the expectation that Kawasaki engineers are infallable and that replacing these tensioner parts and resetting supposedly automatic tensioners would be a normal practice. If it is automatic shouldn't it be automatic? Why should I "reset" or back out until I hear a click, effectively doing a manual tensioning and also making it too tight? I don't buy it. One guy on the KLX site thinks it's okay to replace HyVo chains at 12,000 miles. Those chains are the same design used in some automobiles that run for about a lifetime and on the primary drives of many in-line fours. Other guys think it's okay to back out the mount bolts to effectively override the automatic system.
Now to address what I observed before making my first manual tensioner. The rack and pawl design with a spring will constantly put some minimal pressure on the chain slider which would promote wear. The spring isn't strong enough to resist kickback in the chain under crank deceleration, so it isn't of any value in tension control in that area. What it does is put enough pressure on the rack to push it forward and the pawl clicks in as the chain seats in and cam drive wear occurs… but not always completely.
The key point is that the automatic tensioner clicks in incremental amounts. Cam chains wear/seat dynamically (no increments). When the wear, which by my manual tensioner adjustments has proven to be minimal, isn't enough to move the rack forward forward enough to seat in, but just barely over the tip of the tooth there will be problems. And of course there is no way to tell this. Under cam drive deceleration the rack can kick back hard enough to force the rack back over the pawl, damaging the edges of both by chipping off the edge. This is the same effect as the rounding of shifter dogs when gear boxes are abused with incomplete or missed shifts, but on a much much smaller scale. It takes a magnifier to see the wear (actual rounding), but not the evidence of the wear (polishing of teeth). If this occurs over and over the edges round, much like shifter dogs can, but eventually the rack may start skipping over multiple teeth.
After two of the OEM tensioners in 15,000 miles, the second one costing $70 initially and then about $300 in rebuild costs after it failed, I have no qualms about recommending a manual unit. With simple adjustments on fairly wide intervals after seating in of any new components, the unit is reliable as a rock. I've got 28,000 on my bike with a manual unit, I can't remember now when the last adjustment was made, but it still isn't making any rattling noise except when cold and that is due to play allowed for thermal expansion. I have another rider with a Concours who has 23,000 on his with the same minimal adjustment. Less than one full turn of the adjuster bolt. It is so small a movement if you look at the OEM rack you'll understand why it is possible to have one go bad and another one go without issue. It's just not worth the $70 for the automatic one if it fails again. The manual units are more reliable, the biggest problem with them is when a rider doesn't recognize when it rattles it is time to adjust it.
Now if you adjust the manual tensioner the way I describe it, or another way I learned from the Eliminator owners, you will have taken virtually all the play out of the cam chain drive, but put virtually no tension on it. The OEM automatic tensioner's spring actually does put unneeded tension on the drive all the time, pushing in. All that need be done is take out all the slack, that is ideal.
The play is taken out by either listening for the rattle caused by the loose chain play, which can also be felt if actually doing the turning in by hand. I will tell you I put a socket on my inch/pound torque wrench, held it and twisted as hard as I could... I couldn't even get the beam to deflect. So obviously hand tightening is nearly impossible to overtighten, but I still go by the sound and feel.
Since this is all done at full operating temperature everything is thermally expanded to probably a thousandth or two of maximum growth over all, all inclusive. In other words the drive is as tight as it will get due to expansion. This will result in a very tiny amount of slack when the engine is cold, but that slack is so little it will be inconsequencial as my 28,000 miles show it to be.
As for the chain, again those chains are the same design used in some automobiles that run for about a lifetime and on the primary drives of many in-line fours. They are known for durability when bathed in oil - which they are. Do the research on the internet, I did. I also have never seen a cam chain actually break in the 22 years I spent in a mid-size dealership where I used to love to go hang out in the shop. The one thing I have seen is damage caused by loose cam chains beating up the sliders, variable cam timing as the chain slack allows it to vary by a large amount when the tensioner allows .250 movement when the rack pushes back and forth over 3-4 teeth, and overly worn cam chains from that slapping and snapping around. I will say I did see some Honda ATC200 engines, which use a roller chain, that didn't have the manual adjustment done on them at all, resulting in a lot of chain slap... enough to break the tensioner sliders in them and actually cut through the cylinder cam drive tower area on one. Incredible!
Now the negative on the manual unit. You have to be aware of any ticking coming from the left side cam drive area when it's hot, so you can k ow when to adjust it. That's an actual audible signal that is far quieter than the clatter from a failed OEM automatic tensioner, indicating far less play. It's usually a small adjustment of 1/8-1/4 turn of the adjuster bolt (one full turn is .060" on the M8-1.25 bolt I use) and might only come about every several thousand miles.
You'll actually check your valves more often than it will need adjustment. All you do is every so often at the end of your ride let the bike sit there and run while you take off your helmet and listen on the left side to see if it's ticking at all. Just don't confuse valve tick from the head with chain ticking from the tensioner area. I even got a mechanic's stethoscope to do mine just to be sure. It was more for the Zephyr where the drive is in the center of the engine, the outside cam drives are easy to hear."
This sums up what I've learned over the past ten years from both observation, reading, and my mechanical engineering background. I hope that helps.
#22
09-21-2010, 12:20 AM
Gary, it's under Krieger Tensioners on a Google search, but hopefully Mark will respond. And BTW, for total disclosure, I paid for my tensioner...no freebie. I was just happy to help provide some dimensions and input to be able to get one.
#23
09-22-2010, 12:02 AM
Gary, I've got the order in to get the tensioner bodies cut. That's what I am waiting for. Should be about a week... feel free to either PM me or email, I think you can from here. The google search will call up my site, which is about half done.
The price on the KLX250/300 unit is going to be $32.50 plus shipping per USPS flat rate priority ($4.95 in U.S., $11.45 for Canada, and $13.45 for the rest of the world), It will include a couple extra gaskets, since they are special laser cut items. Kawasaki uses an O-ring, but I'm using a gasket to eliminate the machining cost. It also includes a ball end 6mm allen wrench for adjustment to fit the special allen nut that had to be used - believe it or not, one of the most expensive parts. I don't have pictures yet, but will. Oh, and of course a couple of good quality stickers - ya gotta have stickers.
I think it will help anyone who has tensioner issues. The instructions should be sufficient to get it tensioned better than any tricks with a stock unit. The whole thing is kind of a misnomer - the tensioner actually just takes out the slack, it shouldn't be putting much of any actual tension on the chain. That's why the stock unit has a really weak spring, they don't want excess tension on the chain. That's why forcing the stock unit to click over by pushing in on the rack or loosening the body then retightening it after it clicks is not a good solution to the problem.
This is mainly a sort of fun project for me, I'm a middle school industrial technology teacher with a mechanical engineering background and 10 years in industry. I got into teaching again after a layoff nine years ago. Both areas are fun for me. If I had to make any sort of living with the tensioners they'd be about twenty bucks more... but it's more about the adventure and the bikes.
#24
09-22-2010, 12:04 AM
For what it's worth, don't fix it if it ain't broke. If/when it does go bad then replace it with a manual one. If you want one on the shelf ready to go, that's fine. But I'd wait until it goes bad or if you did a rebuild before switching out... but that's just me.
#25
09-22-2010, 03:40 AM
Same advice you gave me...which I appreciate! But, I'm about to do the Bill Blue 331, would that change your advice? Or, still wait and see if it ever fails? Thanks for all your hard work, and willingness to share it with your fellow riders!
#26
09-22-2010, 04:11 AM
I don't know...I think Mark is just trying to be diplomatic. He's not making much money on these things at just over $30 each, so he's obviously not a very good capitalist....LOL!
Seriously though, my take on the whole deal is that the stock tensioner is a very questionable component. The good news is that it will almost never result in the chain flying the crank gear or cam sprockets resulting in valve and piston mayhem...but...it will result in premature chain wear and a goshawful, annoying noise. It was utterly ridiculous for a chain to be worn out in less than 10000 miles in my case. What's a cam chain cost?...about $80? What's a manual tensioner cost? Plus, there's the peaceful sound of silence.
Seriously though, my take on the whole deal is that the stock tensioner is a very questionable component. The good news is that it will almost never result in the chain flying the crank gear or cam sprockets resulting in valve and piston mayhem...but...it will result in premature chain wear and a goshawful, annoying noise. It was utterly ridiculous for a chain to be worn out in less than 10000 miles in my case. What's a cam chain cost?...about $80? What's a manual tensioner cost? Plus, there's the peaceful sound of silence.
#27
09-22-2010, 02:07 PM
Join Date: Nov 2005
Location: Washington
Posts: 21,060
Don't wait till it breaks, every mile that you have unnecessary chain slap mean wear. I would like to get one of these manual tensioners. If you can't wait for one, then the next best thing is to adjust the one that came with the bike. My bike is so quiet now its amazing!
#29
09-22-2010, 10:31 PM
I'm not going to be able to sleep soundly at night, knowing that I could put this manual unit on and be treating the little girl "right". I'll get in line for one!
#30
09-23-2010, 10:48 PM
Well, I'll post and PM as quickly as I get the tensioners done. I'm going to give a call tomorrow to see if the bodies are cut and I can do the rest. If so, I'll be up next week.
A tensioner that goes bad is not instantly catastrophic. It isn't a risk in a few hundred miles. Its a few thousand that makes problems. So if it isn't making noise right now, ride. I'm still not overly big on any of the ways to "tighten" the stock unit since it involves putting tension on the chain that is only slightly better than having a tensioner go bad. It wears parts. As a stopgap it will work, but the misnomer of a cam chain "tensioner" makes it sound okay. Racers using manual tensioners don't put actual tension on the cam chains, only take out the play. Thus that is what I've done and what I instruct to be done. Excess tension can not be heard, so the bike being quiet is no surprise... unless it's really tight, then it will drag down the idle and possibly make noise. Some riders who've consulted with me on adjusting the tensioners I make have made the mistake of overtightening them. Upon loosening them up and adjusting properly the idle comes back to normal and any chain noise disappears.
A tensioner that goes bad is not instantly catastrophic. It isn't a risk in a few hundred miles. Its a few thousand that makes problems. So if it isn't making noise right now, ride. I'm still not overly big on any of the ways to "tighten" the stock unit since it involves putting tension on the chain that is only slightly better than having a tensioner go bad. It wears parts. As a stopgap it will work, but the misnomer of a cam chain "tensioner" makes it sound okay. Racers using manual tensioners don't put actual tension on the cam chains, only take out the play. Thus that is what I've done and what I instruct to be done. Excess tension can not be heard, so the bike being quiet is no surprise... unless it's really tight, then it will drag down the idle and possibly make noise. Some riders who've consulted with me on adjusting the tensioners I make have made the mistake of overtightening them. Upon loosening them up and adjusting properly the idle comes back to normal and any chain noise disappears.