In the end I just took the headpipe off and it was done in a flash with the additional workspace. Much quieter today. I'm not sure I'll play around with the fine tuning. Like others I came as close as I could and then backed off a bit and then turned it in slowly untill the noise went away. In the end I was right about where my "calibrated fingers" detected the increase in pressure to be.

Good product. Kudos to Mark for his work. Not his fault I was suffering from fumble fingers last night.

 

I ordered it Friday and got it today. Put it in too. The whole cold finger tight adjustment bugged me. I think I have really strong fingers. I did the hot adjustment which worked for me. Bike sounds great. I also wasn't sure I was hearing all the same noises everyone else was describing... until I looked at my stock auto adjuster. It was obvious that the thing has been slipping.

 

Okay, think about this before doing the fine tune...

From what I've found, there is usually only about an eighth turn difference between the cold set and the fine tune. If you take the M8-1.25 thread movement on one turn you will find it is going about .050" per turn, that 1/8 turn is about .006". That is the thickness of a couple human hairs. That's why I'm kind of figuring the fine tuning isn't critical. If you can do it without burning off your finger tips and want to do so, fine, but it won't be hyper-critical. Especially when you consider the play allowed by a failing tensioner based on what I've seen (and shown on the web site) is over 1/4" (.250") based on the wear patterns I've seen on some tensioner teeth and now the back side where it wears as it slides in and out.

So, don't feel you're neglecting anything vital. If it starts with a very slight ticking when cold then quiets down, you're good to go.

I got into the fine tuning deal when the guys I worked with told me that was a good way to adjust the tensioner when it ticked while hot. Of course that was on the KLX650 where the adjuster is wide open. After doing the cold set on the Zephyr with the tensioner tucked away in the middle, I didn't bother doing the hot set. I did the math I just mentioned and realized it just wasn't a big deal for .006" to.010" movement. To date it is over 12,000 miles without further adjustment.

I will say the fine tuning is probably a good way to make sure the adjustment (notice I say adjustment, because technically you are not putting any tension on the chain) isn't overly tight if you are concerned with going overboard or if it is just plain easy and convenient (neither of which may be true with a hot exhaust header right there). Of course TNC's extension/socket/piece of allen wrench deal is the real trick. That's why I sent the 6mm ball end allens - so you could cut off the end with the ball and use it in the "magic TNC tool".

Good riding to you all and keep it on two wheels unless intended to go unicycling!

Mark

 

First, I want to throw your pictures up on the web site for the 250 to show the wear one of you has seen, if that is okay by you. Now you and those who see those pictures understand why the noise is so loud. That's at least 1/4" of play allowed in the cam drive. Now you see why I don't see .006" to .010" as too critical when it comes to a bit of play.

For the rider who's not had any problem, if someone is fortunate to have all the mechanical aspects fall in place and the tenisoner does work well, that's good for them. It is for those where it doesn't work that this part is handy. Just be aware of how a quiet cam drive sounds and if you start to hear noise from there, do something about it. Personally from my experience the manual unit is the least expensive method to KNOW the adjustment is good.

I've had Concours riders go with the manual tensioner around 60,000+ miles when the mechanical variables hit the point where the tensioner fails to work. Had the same with KLX riders, but more often and at lower miles. There is no set interval or anything, due to machining variables and the seating in/wear process with chains and sprockets of the cam drive.

The bikes where it is really critical are the Honda VTR1000 Superhawk and Firestorm, the front tensioner doesn't get sufficient oiling to prevent the spring in them from corroding and catastrophically failing. They don't have the same style set up as the Kaw and when they break they BREAK. The chain goes slack, timing can jump and valves can hit pistons, destroying valves, pistons, and/or heads. Be happy all yours did was rattle for a while!


Second, any of you who think you have strong fingers test yourself to see if you really are that tough compared to the tiniest of levers. Put a socket on your inch/pound torque wrench, set it at the lowest setting you can get. Hold the socket as tight as you can with your hand and turn the wrench. With my beam wrench I couldn't even get the indicator needle to move relative to the scale - I can't turn 1 inch/lb torque! I doubt anyone could do even two. Your hand will slip. That is gripping as tight as you can by hand. Now how tight do you think you are turning a nut or allen wrench shaft with your finger tips even if you think you are "the human vise grips"?

Now if you use any sort of lever, even the short end of the L on the allen wrench, you may be going overly tight. You should use finger tips only in a linear fashion, not out at the end of an allen wrench or ratchet. Even with the cold set, the "magic TNC tool" is the best set up. Using finger tips on the end of the extension would be fine. Remember, all you're doing is taking out the slack. I have used a wrench when doing the hot set on my 650 and have to be extremely careful. It takes virtually no pressure to turn the wrench while listening for the ticking.

One last thought, you have to figure that the 250 tensoner is like a big leaf spring supported on the ends. It has some flex, so if there's a small bit of loading, it won't be big pressure on the cam drive. Again, just how tight can you tighten using finger tips? Most other bikes have that tensioner adjustement in the middle with little leaf spring effect. Overtightening them is more critical since it is nearly mechanically fixed and binding. It really can not be done with finger tips on them, but easily done with wrenches. That's why I emphasize the finger tip thing. so much.

It would be interresting to set up a test bench to try out this thing. Take an old slider, have it fixed at one end, the center pressing on a scale, and a bolt pusing down on the other end then see just how much the scale can be loaded while tightening the bolt with finger tips. Hey TNC, got any junk laying around to play?

Later...

 

Sorry, Mark...no extra junk here.

 

Yeah, but next time you have one out of the bike you're going to think about it...

It does make me curious just how much deflection/tension there is able to be generated by finger tightening that slider. Can't be much.

 

I messed around with the tension more than I should have, but wanted to get a feel for it. I had a XS650 years ago that had a sloppy tensioner on it and the chain jumped a tooth. Took me a while to figure out how it failed.

When I tried the cold adjustment everything was "ticking". The tensioner bolt was pulsating and backing out when the motor was running. I could thread the tensioner bolt in and out without any change in sound or feel. So I backed it out til I heard the ticking and in until it stopped. It was about 2 flats of the jam nut in from where the sound started. I waited until the cooling fan kicked on and checked my setting and went for a ride. No ticks. So today with the motor cold I got a full turn on the tensioner with my fingers. That's about .048". Is it better to be loose with no ticking than to be excessively finger tight? I went for .048" loose. Oddly enough each tooth on the auto tensioner is about .048" and I was jumping 5 of those and thought nothing of it. Analysis paralysis has set in.

 

Yeah, I think it's easy to over analyze the adjustment here, and that pulsing feeling through the adjuster shaft can be disconcerting to some I'm sure. This is what I liked about my 1/4" drive extension setup pictured a little earlier. That much distance with a wobbble end on the extension and all resulted in most of that pulsing being damped out. And since I didn't have to worry about the heat from the pipe, I made my final adjustments with a fully hot running engine, very conveniently, with the ability of finite adjustments.

 

One question, why did you change it when you had it set by hand and there was no ticking when warmed up? I'm not clear on whether you are turning it in a full turn tighter or out a full turn looser...

Let me preface the following comments with the fact that I have yet to be able to do one of these on a KLX250 or 300. I have done them on a number of other bikes as well as my own. I may be off, but these are my thoughts. Perhaps TNC or the others may have input. The goal here is to try to make things as best for your bike, not to insult or belittle you or anyone else, so bear with my emphasis in some areas. It is to try to emphasize the point so you and others don't miss it.

Adjusting the cam drive isn't really some trick, it's just getting the play out of the cam chain. There is a reasonable range, just as there is that range of clearances for valves. We are shooting to get in that range, not too tight yet not too loose. A bit looser is not horrible, remember when the automatic one fails it allows like a quarter inch of play, not a few thousandths. The best set is when the tensioner might lightly tick when cold, but is quiet when hot. That tells you the thermal expansion is taking up the play. The KLX250's long spring tensioner supported as it is is actually going to be more tolerant of a wider range of adjustment than some of the other designs.

The cold set is done with the engine not running. You turn the adjuster in with your finger tips until it is snug, about all the play taken up from the cam chain. You don't need to be the "human vise grip" on this. Then turn the engine over with a socket and ratchet/breaker bar while trying to snug up the adjuster a bit more if it has more to go. You may have all the play taken out already, but try it anyway. The turning of the engine pulls the front run tight putting all slack in the back run. Back off about 1 flat (1/6 turn) and tighten the lock nut down. It may tick when started and cold, but it should quiet down when it is hot.

If you do the hot adjustment, do not let the adjuster bolt back out while running, be ready to do the adjustments and control the bolt. As TNC pointed out his set up is the best, no burnt fingers. (I did have someone using an allen socket and one of those cable flex drives.)

You listen to the cam drive as you move the adjuster - if there is ticking you slowly turn the adjuster in until the ticking just goes away. If there is no ticking you slowly turn the adjuster bolt out until you just faintly hear ticking, then slowly back in to stop the ticking - which will be less than 1/8 turn. If it is more you are turning too far too fast. This is quite literally fine tuning. As I said before, odds are the cold set with the engine off will be close enough that the fine tuning should take less than a quarter turn. If your adjustments are in the full turn range you are overshooting and making too large of changes. The transition from ticking to not ticking will quite literally be within a quarter turn per my experience.

I hope some of this helps...

 

Mark, I think the "fine tuning" issue some have is just that nagging pursuit of "perfection" and maybe even a little concern that it's not adjusted at the ideal spot. As you well know, probably most riders now never had the pleasure/grief of dealing with factory manual tensioners, so it may be a bit of concern that they'll bugger up their engine. Lotrat's comment probably sums it up well...overanalysis paralysis.