14.09.2010, 10:36
Hat das von euch schon mal jemand durchgeführt?
Auf der dieser deutschsprachigen Seite gibt es auch informationen dazu.
Nur nicht so ausführlich und auch nicht auf die EX500 bezogen.
Auf der dieser deutschsprachigen Seite gibt es auch informationen dazu.
Nur nicht so ausführlich und auch nicht auf die EX500 bezogen.
FOG from EX-500.com schrieb:Degreeing Cams
Another thing to check before you spend (waste) money on a pipeandajetkit. And or other external mods is the correct timing of your cams. In the case of the EX the Cams are driven by a long chain from the crankshaft and there is no adjustment. This means that the actual setting are fixed by the assembly of many components and could vary from design by a substantial amount.
Some causes of this variation are: Chain stretch, errors in any of the location points of the gears in relation to the crank throws. Variations in the distance from the crank to the cams (like if you milled the head ). A few others as well but you get the Idea.
The timing of the cams has more to do with the Character of you engine than almost any thing else. Because it is the thing that creates the power and spreads it around the speed ranges that the engine is designed to operate within. Max power is only one of the considerations. A good spread of power down low can make the bike more enjoyable than that nice big hit of power up at the top of the revs. Book have been written on this subject and it is way beyond the scope of what I?m doing here. Suffice to say that you can ?Color? you engine here anyway you want. And some ways you won?t want. Were going to stick to putting the cams where the designer wanted them.
Tools:Â A degree wheel, and a way to affix it to the center of the crankshaft.
A pointer:Â this is a piece of coat hanger wire to a case bolt to indicate the Degree of the wheel.
A Dial indicator with at least ½ of travel, and the means to attache it to the head to detect the movement of a valve.
A set of slotted can chain wheels, the stockers can be slotted enough with a ¼? chain saw file.
The means to turn the engine over by hand. I use the bolt that holds the degree wheel to the crank
Procedure:
With the engine on the bench and the gen. side cover, the cam cover, off and the plugs out.
Fit a piston stop into the #1 plug hole. (I made one by removing the insulator from a Spark plug and tarring it to accept a 5/16 screw.). Adjust the stop to hit the piston at a point about ¾ of the way up the bore. Bump the stop, first in one direction, then from the other. The return to the middle of those two points and bolt the degree wheel with the 0 at that point. Fix the wire pointer to be close to the wheel and point to the 0. Repeat the centering steps and bend the wire pointer until the exact center of the two stops is attained. This is absolute top dead center. This step is critical and must be done accurately or the whole Idea of moving you cams is a waste of time.
Now fix you indicator to show the first movement of an intake valve.
Rotate the crankshaft in the normal direction until the cam moves the indicator a little, stop. Note the reading on the degree wheel. Continue turning the crank in the same direction until the indicator returns to the same reading you were at, at the first stop. Write down the reading of the degree wheel.
Subtract the small number from the larger add 180 and divide by two. This is the lobe center of the intake cam. For the EX it should have been 100.
We will now move the intake cam wheel in relation to the intake cam to obtain the 106 number.
Ok that how it done, right here we?ll explain some things that may not be clear.
Lobe centers: That?s the point expressed in the degree wheel reading that represents the exact center of the two points on the cam lobe that return the indicator to the same reading IE: the center of the Lobe.
Cam Timing: The relationship of the cams to the crankshaft is expressed as the number of degrees of crank rotation from Top Dead Center, (TDC) that the crank has to be rotated to just move the valve. On the EX it is like this.
Intake opens @ 45 deg BTDCÂ Before Top Dead Center
Intake closes @ 65 deg ABDCÂ After Bottom Dead Center
Duration 290 degreesÂ
Exhaust opens @ 70 deg BBDCÂ Before Bottom Dead Center
Exhaust Closes @ 40 Deg ATDCÂ After Top Dead Center
Because of the difficulty in determining the exact point of the valve opening we use ?Lobe Centers? To convert the chart above to lobe centers Do:Â 65-45+180/2=100 . 100 degrees lobe center for the intake cam
70-40=180/2= 105Â Â Lobe center for the exhaust cam.
Ok if you did all that above and you got something different, here?s how you fix it.
Remove the cams and remove the sprockets from the cams. Elongate the Bolt holes about 1/8 ? in each direction. Replace the sprockets with the bolts located in the center of the elongation.
Set up the cams as per normal directions and replace your indicator. Now check the intake cam and move the sprocket in relation to the cam and re check. Repeat till you get a lobe center of 100 deg.
Then set the exhaust cam at 105 lobe centers.
If you wish you can ignore the exhaust cam as it has very little effect on the power production.
I can add here that you can use different settings that the stock ones but I?m not going to tell you, except to say expanding the spread of the cams will move the power up in the rev range, and closing the settings will do the opposite.
The operative here is be careful as little as one degree can make a huge difference.
FOG
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