KLX 250 ( 300 ) camshaft mod by Marcelino

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  #561  
Old 04-24-2014, 10:35 PM
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Originally Posted by Klxster
I'm not sure I understand... The ACR is deactivated simply by drifting it out of the cam or by leaving it on the cam and removing the spring. Not sure I'd want a piece of coat hanger running around under my valve cover.
Gotcha! I intentionally stated it was coat hanger to see if someone would comment about it.

First it is not running around in there. Second, think about it... suppose I said low carbon malleable steel wire... then compare that being bent into a position where it cannot move, versus a spring that is simply hooked in the holes...

What would you think now?

I know enough about materials to know what I was doing. How many times do you have to bend a coat hanger back and forth before the material fatigues and breaks. Now you bend it one time at two points to make the U bend, then you bend another part one time at each end to lock it in. Are you honestly going to be concerned about that piece of coat hanger breaking? It is probably more malleable than safety wire that would be used in a motor. No worries.

If I had to buy the wire in a spool I'd have to buy at least 25 feet or so in a roll, I got the coat hanger for free, it fits and works. I also would rather lock the release in a non-functional position than letting it loose. But that's just my preference. Being able to show some others of like mind and that the material used to do the job is free and functional is good too.
 

Last edited by klx678; 04-24-2014 at 10:39 PM.
  #562  
Old 04-24-2014, 10:57 PM
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Originally Posted by klx678
Gotcha! I intentionally stated it was coat hanger to see if someone would comment about it.

First it is not running around in there. Second, think about it... suppose I said low carbon malleable steel wire... then compare that being bent into a position where it cannot move, versus a spring that is simply hooked in the holes...

What would you think now?

I know enough about materials to know what I was doing. How many times do you have to bend a coat hanger back and forth before the material fatigues and breaks. Now you bend it one time at two points to make the U bend, then you bend another part one time at each end to lock it in. Are you honestly going to be concerned about that piece of coat hanger breaking? It is probably more malleable than safety wire that would be used in a motor. No worries.

If I had to buy the wire in a spool I'd have to buy at least 25 feet or so in a roll, I got the coat hanger for free, it fits and works. I also would rather lock the release in a non-functional position than letting it loose. But that's just my preference. Being able to show some others of like mind and that the material used to do the job is free and functional is good too.
ACR aside, how does the bike run now that you've done the MCM?
 
  #563  
Old 04-25-2014, 01:31 PM
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Originally Posted by klx678
Gotcha! I intentionally stated it was coat hanger to see if someone would comment about it.

First it is not running around in there. Second, think about it... suppose I said low carbon malleable steel wire... then compare that being bent into a position where it cannot move, versus a spring that is simply hooked in the holes...

What would you think now?

I know enough about materials to know what I was doing. How many times do you have to bend a coat hanger back and forth before the material fatigues and breaks. Now you bend it one time at two points to make the U bend, then you bend another part one time at each end to lock it in. Are you honestly going to be concerned about that piece of coat hanger breaking? It is probably more malleable than safety wire that would be used in a motor. No worries.

If I had to buy the wire in a spool I'd have to buy at least 25 feet or so in a roll, I got the coat hanger for free, it fits and works. I also would rather lock the release in a non-functional position than letting it loose. But that's just my preference. Being able to show some others of like mind and that the material used to do the job is free and functional is good too.


If I remove my valve cover again , I will add the wire. But until then I think it is fine without it.
 
  #564  
Old 04-26-2014, 11:53 AM
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If it works fine, no problem. I'm just taking an extra step to know it is totally disabled. I figure it's in pieces at the moment, why not. Definitely makes the cam mod easy and your telling me the bike starts good without the spring gives hope it will work well with the KACR locked out. If all is good I may pop the CR out at next valve check.

I have been careful to bolt the cam cover back on after every removal to avoid having the gasket shrink up and screw up. I hope it works and I don't have any oil leak when done.

Later...
 
  #565  
Old 05-07-2014, 05:38 AM
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I think this mod is coming up very soon for me...I'm running out of things to monkey with..

And my friend told me recently that his son has a 2014 KX250F MXer..maybe a chance to do some roll-ons will come up soon when we go watch him practice jumps a few km away.

- But he'd have to be in 2nd while I hit it first in 1st gear Then maybe the race wouldn't be over with immediately ..





 
  #566  
Old 05-11-2014, 06:17 AM
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Since the subject of a too-narrow LSA once the MCM has been done came up a few pages back, what about redrilling additional holes in the EX cam gear away from the current holes to have it at 4-5 deg retarded instead of the 8-10 deg the cam mod produces (depending on how many degrees the MCM actually moves the cam)

Placement of the new cam gear holes would determine the change in cam timing

I realize that many MCMs have been done without a problem, but the additional holes thought came to mind

 
  #567  
Old 05-11-2014, 02:33 PM
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Originally Posted by Richard Avatar
Since the subject of a too-narrow LSA once the MCM has been done came up a few pages back, what about redrilling additional holes in the EX cam gear away from the current holes to have it at 4-5 deg retarded instead of the 8-10 deg the cam mod produces (depending on how many degrees the MCM actually moves the cam)

Placement of the new cam gear holes would determine the change in cam timing

I realize that many MCMs have been done without a problem, but the additional holes thought came to mind



it would be better to simply machine the holes to make one long slot - totally adjustable. It's been done for decades.



Likely would require a mill to cut the slot or some skillful grinding with a Dremel. Possibly could even be bought fairly reasonably if the sprockets are similar to those used on one of Kawasaki's big 4 cylinder bikes.
 

Last edited by klx678; 05-11-2014 at 02:42 PM.
  #568  
Old 05-14-2014, 03:41 AM
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Last time I attempted to slot cam sprockets was way back in the mid 80's on my 750 Interceptor. Turns out that the material Honda used was SUPER hard and defied any normal machining techniques-the only way left was to use a EDM machine to vaporize the material. At that point I said F it and left it alone. I would suspect that it probably hasn't changed over the last 30 years so you may have a challenge ahead....
 
  #569  
Old 05-14-2014, 05:10 AM
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Not to mention getting the holes in the exact correct position
 
  #570  
Old 05-15-2014, 01:02 AM
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Originally Posted by Richard Avatar
Not to mention getting the holes in the exact correct position


That's why it would take a machine shop - they could do it with a carbide end mill, slotting it for total variable adjustment.

As for my bike - fired up virtually instantly. Virtually 30 second warm up and I rode it down the road working it a bit for about a mile, until it tossed the chain on the way back. Seems the case guard at the CS was out of place and caused the masterlink clip to come off. I got to push it, much lighter than a 650, for about 1/2 mile.

Cheap chain, junk sprockets - so I ordered up a DID X-ring and another set of sprockets. I thought I could use the ones on the bike for the run in Michigan in the sand and all, but when I took off the rear wheel to put on the brake rotor to match the front I saw the rear sprocket was hooked far worse than I thought. I don't think it would have kept the teeth for a week. Total crap with total crap chain.

Now to get the chain & sprockets on and go run my brother with his 06. His is jetted plus Dial-A-Jet and 300 pipe/muffler. Mine is stock with shimmed needle with the Dial-A-Jet and the MCM. We will see how close they run. He will be running a 13/42 and I a 13/43.

It is better than before, but not sure how much. Mainly no problem with warm up, no stumble and good response right off. I need some time to see how it performs with a chain on it!
 

Last edited by klx678; 05-15-2014 at 01:05 AM.


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