Cam Journal Wear

Here are some pics of my intake cam journals and intake cam. The bucket is stuck in there. I think it is time to get a new torque wrench. After searching previous posts and reading about Engine Dynamics, I will be giving them a call about fixing up the journals. Is the wear on the cam enough to warrant a new cam or does it look fine to the professionals out there? Thanks for the help.

Cam Journals

Stuck Bucket

Intake Cam

Intake Cam

My guess is that is Aluminum from the head deposited on the cam. I think you could clean it of the cam and save it. I'd try some muratic acid from the pool supply store.

Tear a long, narrow strip of fine emery cloth and wind once around each cam journal (the journal is the actual bearing surface on the cam. The bores in the heads are the bearing surfaces). Polish the cam journals free of any deposited aluminum and measure them for wear. More than .001" should be rejected.

I had a problem with the cam journals on the head off of my 99 400f. During a rebuild I noticed the cam was "binding", hard to turn when the caps were torqued. I talked to several shops in this area and they were all clueless. (one suggested I leave the caps loose so the cams would turn easier) I did an online search and came up with Engine Eyanmics. Gave them a call and they were super to deal with. Sent them my head and they line honed the journals (along with new valve seats and guides and they even set the vavle clearance). Bike is back together and has about 30 HARD hours on it since the rebuild/head work, have checked everything a couple of times and all is in order. Come to find out the problem is inherent to the earlier YZF's. When you adjust the valves and re-tourqe the cam caps, they squish and tolerances get tighter.


99 YZ400F

02 XR250R

06 YZ450F

Ive used engine dynamics on my YZ400. They do good work. send it to them.

Thanks for all the input guys. I'm gonna call Engine Dynamics today.

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