Removed my ACR and then repositioned into the camshaft just fine. Only problem was that when I put it back in the engine and then was gonna do Marcelino's "blade test" to check position, discovered that I had turned the ACR the wrong way.

Well, practice session is over and back to the drawing board tomorrow.

Note: to help with pressing out the ACR, a 12mm bolt about 4 to 4.5 inches long works great! Just make sure the camshaft support is good.

 

Hey Kansas, Would you mind a picture of the cam support? and perhaps a couple of the procedure? Thanks

 

I have deciced to go all the way, pull the exhaust cam, re position the acr, set to marcelino timing. I can always put it back. Then REJET since it needs it now and I don't want to do it too many times.

After a little more riding, it wants to pull the front wheel in second but will not yet. IF the exhaust cam does that, I will keep it there.

I have a good base line to compare it too. The first thing that attracted me was the quiet intake noise. Perhaps the exhaust cam will help. If not its run with air box LID ON.

If I were running with the lid off and my cam chain got really loose, I would not even hear it.

Must have quiet bike intake and exhaust.

It may be a day or two before I can get to it.

David

 

The original reason that started the cam mod was the intake noise , I just couldn´t take the growl it would make with the air filter lid off .
Later I realised the power and especialy the torque improvements it could bring . I really feel a lot more secure about changing gears when I´m going up some mountain . Using the bike without the lid would be a little .... wasteful .
The jetting is a little different in between with or without the lid ( and snorkle ).
So far it seems that the correct sizes for the 350 with the cam mod are DJ 40 for the pilot and 132 for the main , third position clip on the needle . I´m not sure it will be exactly that but it´s a good startig point . I think the mixture screw would need to be 1 1/2 -> 2 turns out .
Boy , I really wish somebody would go to the dyno with the bike allready so we could exit this " fog " . 50 - 100 bucks what they charge for this is really small in comparacing to the hudreds and hundreds of dollars people spend on cilinders , exhausts , pistons , trinkets etc. Shoving 1000 buks at a bike and then not tuning it is pointless . Share your fidings , make a post and share your knoledge ; don´t just post when you broke something , and need help with fixing .

 

This may help with the ACR adjustment.

It's time to use a little math.
You know how many degrees you will be changing the cam timing, 10.5degrees according to Marcelino's information. You will be moving the ACR that same amount in the opposite direction, on the "newer" version of the 250's. 10.5 / 360 = percentage ( % )of a full rotation that the ACR needs to be moved.
Measure the diameter of the cam near where the ACR is located. Multiply by pi to get the circumference ( C ).

% x C = measureable distance on the circumference of the cam to move ACR.

Mark a referrence spot on the ACR and the cam circumference. These two should be lined up.
Measure the distance from the above equation IN THE CORRECT DIRECTION from the stock mark on the cam and make another mark.

Separate the ACR from the cam, rotate it to align the marks and press the ACR back onto the cam.

I hope that doesn't add to the confusion.

Ride on
Brewster

 

Finally got the ACR positioned more correctly this evening and put everything together without any issues.

As my test ride report stated on Sunday for just the valve timing, there are no problems at all in that area. For me, the bike is a little peppier off idle. I reconfirmed that the bike wants to clutch-feather forward in 1st gear where before it didn't want to (stock 42/14 ratio). There is less off-idle bog when pulling away from an intersection and I can accelerate through the gears a little faster. Takes a little less throttle for a given speed, all other things equal.

It even starts strongly when it's hot, too!

All that's been done so far is the timing and ACR position adjustments. Air box lid is still on and will ride a few days that way to fully assess the mod. Then I'll remove it and see how it goes from there. I know the charts show a potential for improvement. Performance checking is gonna be difficult for the next few days ahead because we have a string of days forecast for 100+ degrees and that robs power in and of itself.

Way to go, Marcelino!

 

I wonder if the DR650 could use the same cam changes as the KLX?
It has a single cam so there is no moving the sprocket.
I'm just wondering if a regrind with the same degrees as this KLX would improve it?

 

Brewster and Marcelino may want to skip this one. It's crude and messy but effective, though. I used the method twice for ACR removal. Not much chance of damage to the shaft/ACR but I can't say the same about your hand or arm. Read on if you dare.

First of all, if you can get the ACR out with a proper hydraulic or large manual press and support fittings at a shop, do so. Don't say you weren't warned. Stop here.

This may illuminate some light bulbs in some folks heads: Ever removed a manual transmission clutch pilot bushing in an automobile using grease? My way was kinda the same but different.

1) A 12mm bolt is the largest that will fit into the camshaft. Get one about 4 to 4.5 inches long. Ace Hardware has them for sure. Don't know about Lowe's, Home Depot, etc.

2) Grind the threaded end nice and flat and eliminate any sharp edges.

3) Take some grease and put about an inch or so into the camshaft. Don't need to be too precise, several pumps of a grease gun will do.

4) Bleed the air from inside the shaft by pressing on the bolt and/or spinning the camshaft on the bolt the same way as you would spin a nut to run it down the threads. Air will tend to migrate down the threads and out. You'll know when you have a good bolt-grease-ACR connection. You'll also hear the air popping and spitting as it works its way out. Sort of like camshaft flatulence. At the end of the process there will be no bolt sponginess. Just good solid connection between bolt, grease, and ACR.

5) For whichever hand you're using, put on a nice, thick, insulated winter glove to protect from mechanical shock.

6) Wrap a couple of rags around the camshaft/ACR to prevent the ACR from shooting out and also to catch any grease geyser that may follow it.

7) Find a good solid (steel is best), hard surface. I used the flat anvil portion of a large vise in my garage.

8) With the assembly gripped kind of loosely in your hand, where it feels most comfortable with the lobes and ridges, play like you're "throwing" the bolt head down against the hard surface. Don't "pound" it into the surface by gripping tightly (like I did at first) or else you will likely contract arthritis in your hand this time next week from all the mechanical shock. Let gravity and the mass of the assembly do all the work. Do it like you're "flinging" the bolt head/shaft assembly against the steel. Just don't let go...

9) Tonight (maybe last night, too, but I was on a learning curve, then, and not counting), after probably less than 20 thwacks this way, I felt the ACR pop loose into the shop rags. You did use rags, didn't you? If not, after you've found wherever the ACR landed, clean up all the grease that went everywhere. Inspect the ACR for damage.

I used grease for this procedure as insurance against the nightmare of the bolt expanding inside the shaft from metal to metal contact. I don't know the hardness/softness of either the bolt or the ACR, and I wasn't about to take chances.

It's an ugly procedure but if done right, won't cause any damage to shaft or ACR but your hand/arm may feel it...

An alternative to try is a pneumatic hammer for the bolt. May save some wear and tear on your hand/arm. Would have tried this myself but my compressor is down...

 

Here is a great drawing for a jig to do the ARC.
KLX ACR mod

 

Man, it sure has gotten quiet on this cam timing mod. So is anyone who has a 351 actually going to do a valve clearance check with the piston? Is anyone at this time preparing to install a new 351 kit who could do this check without having to disturb an already running engine? No offense to jhoff, but he did go a bit *****-nilly on his build and cam timing mod, so I'm still not sure it's an inherent problem with the 351.

Apparently it's a non-issue with the 250 if I'm reading correctly here. To confirm, Marcelino, yours is a stock 250 piston, correct? And kansas-klx, yours is a 250, right? Is everyone just mulling this issue over right now, or is that the sound of cylinder heads being removed for clearance measurement that I'm hearing?...LOL!