NEED HELP!!! '03 Cam mod

yeah but finding the guages was the hard part. I check everywhere I could think of. Next option was to drive 45 minutes to Louisville to MAYBE find the guages. It became a time issue. I needed to get her buttoned up. I was supposed toi ride today, but it snowed 3.5 inches overnight, and the roads are in bad shape so I'm stuck at home anyway!!! :thumbsdown:

I guess I got lucky. I went into my local dealer (Malcolm Smith) and they had the shims in stock and the gages hanging on a spinner rack by the parts dept. I guess it makes a difference when the owner is one who actually rides, they know what to stock :thumbsup:

YEah, That's about the only reason I can think of to live in CA!!! tons of tracks and more STUFF for bikes. KY is quad heaven, and bikes are secondary. TX (HOME) is very bike friendly, but sometimes you have to drive to AUS, HOU or DAL to get into some of the specialty stuff.

Thanks!!!

The YZ cam is identical to the WR cam except that the decomp pin is 3mm shorter, and the cam is indexed differently so the timing marks STILL line up.

The only time you change the pin count is when you change the stock '02 or older WR can to give you YZ timing without autodecomp.

I THINK the 4xx engines have 14 pins between marks.

Let me get this straight-no matter which cam ('03 stock yz or wr)is used in an '02 or earlier wrxxx, the pin count will be 14??

Also, how does the 3mm shorter pin on the yz cam effect the compression release-or is the cam designed different on the yz that this allows the same amount of effort to start the yz as the wr.

I'm going to do the mod but still am unsure of going the yz or wr route.

Can the '03 wr cam be rotated 1 pin like the earlier non auto cams to get the yz timing or will you lose the autocomp feature by doing this.

Thanks,

Tom

Let me get this straight-no matter which cam ('03 stock yz or wr)is used in an '02 or earlier wrxxx, the pin count will be 14??

Correct... 14 on the 4xx series engines and 13 on the 250.

Also, how does the 3mm shorter pin on the yz cam effect the compression release-or is the cam designed different on the yz that this allows the same amount of effort to start the yz as the wr.

The YZ cam is indexed to be retarded from the WR cam by the equivalent of one tooth. The cam itself is the same except for where it is mounted to the gear, meaning that the hole for the decomp pin is in the same place.

With the pin sticking out too far and the cam retarded, it holds the exhaust valve open too long on the compression stroke and the engine fails to build enough compression to start.

Can the '03 wr cam be rotated 1 pin like the earlier non auto cams to get the yz timing or will you lose the autocomp feature by doing this.

The '03 and later cams must be installed per design... YZ timed YZ and WR timed WR. You might be able to get away with buying the YZ cam and advancing the timing (go 15 pins) to get WR timing... you'll have a little more compression on the kick, but it should start no harder than a '70s era pinger. I wouldn't do it on a bike with an e-start.

Thanks for clearing that up-all makes sense now.

Just did the mod on a 2000 Wr400 i picked up afew weeks ago. 14 pins between cam marks and it started on the sencond kick and runs great. Kicked it over in my tennis shoes. One thing I noticed is the timing mark on the crank didn't line up with the cams or the piston at TDC with the bike stock. Thought that was kinda odd.

I just put the 03 YZ cam in my 01 WR It runs great and all.

Does the auto decomp cam make a little more noise at idle than the non?

My valves are in spec so its not that.

Thanks

Eric

I didn't notice anyhting. You plugged the decompression hole didn't you?

I didn't notice anyhting. You plugged the decompression hole didn't you?

TT plug

If you pull the spark plug, you don't have to worry about the crank rotating away from TDC...no compression to fight!

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