I plan on moving the cams with the cam mod, but I saw the video where the fellow just retarded the exhaust cam and didn't move the intake cam. I was wondering if anybody had any experience with that? Thanks a lot guys.

 

I think that guy gets his kicks over hoping yall will trash your engines off his video... Try real hard to never watch that video again.

Study the MCM sticky carefully, set aside 1 to 2 hours, re-time both cams, pull the spring off the ACR, enjoy mo-powah.

 

Other than only doing the EX cam, what's wrong with his technique?

 

Some info off the internet - fwiw


You can indeed affect the engines compression ratio by altering cam timing.

The intake valve opens slightly during the end of the exhaust stroke, and this is known as the "overlap" period because both intake and exhaust valves are open slightly at the same time, with the exhaust closing, and the intake opening.

If you advance the cam (especially the intake) ala MCM it will open the valve sooner, and close it sooner, since all you've done is "move" the fixed intake event.

Keep in mind the intake valve doesn't close at the bottom of the intake stroke, it remains open after BDC to attempt to get some additional mixture in the cylinder using inertial ram.

Since the piston is traveling up on the compression stroke while the intake valve is closing, the mixture takes the path of least resistance, and so the piston shoves some of the mixture back up the intake port before the valve closes.

If you close the intake valve earlier on the compression stroke (ala MCM), the rising piston will have more mixture to compress since less was pushed back up the intake port.


The intake valve duration , especially when the valve closes can have tremendous effects on dynamic compression. Now understand dynamic compression has almost nothing to do with static compression ratios.

 

Why isn't there an affordable aftermarket cam kit?? Hot cams are you listening!!! Or programmable CDI...

 

Because neither are inexpensive to make. Even back in the mid 90s a single cam for a 2 valve Yamaha was near $125 if I remember right.

 

Nothing about the video - I saw someone trying to use recently - was correct. The mod is dangerous to the health of the engine if done wrong. While I won't get into how to do it right, - that is for the owner to research and accomplish - I will try to help save engines with blatantly wrong instruction/videos.. The vid I watched had the ex cam set back 2 teeth on its' gear PERIOD. No mention of the ACR on its' end either.. RECIPE FOR DISASTER !

If you can't grasp the mod using the MCM sticky and/or KLX768's post, don't do it.

 

He edged the EX cam gear bolt into the gear's IN hole after rotating the cam gear two teeth to the right. Him not touching the ACR would only make it hard to start rather than a disaster, no?

 

You can get a set of cams for a drz400 for around $150... Klx cams are not much different. Programmable cdi would just be icing on the cake.

 

URL: http://pages.ebay.com/link/?nav=item...684179&alt=web

Do your research, they say it doesn't do much for performance.