Ride Review: OEM Cams vs. Stage 2 Hotcams vs. Graves Yamaha (Web) Cams

[KZaj43B]

I know when I was looking to buy camshafts earlier this year I couldn't find the information that I was looking for, so i'm writing it here so hopefully I can help someone out in the future with this info. The bike is a 06 YZ450F, set up for flattrack ( similar engine set up for sumo). Slightly modded airbox, 12.8:1 JE, PR2 valve seats, Kibblewhite dual valve spring/titanium retainer setup, Yoshi TRC Slip on with a few different head pipes. Since the beginning of the year I have tested OEM cams, Graves Yamaha Supermoto Cams (#963 Web Camshafts), and most recently Hotcams Stage 2.

OEM Cams:

Great MX cams, good for TT style racing too with lots of rpm change. Pulls great out of tight turns. Power falls off quite rapidly after roughly 8500. For 1/4 mile flattrack gearing would have to be tall to keep the bike lower in the rpms to stay in the meat of the power. Bike started first or second kick always.

Graves Cams:

Very aggressive cams. Had to install higher performance valve springs and check all clearances when installing. These are sold as full on race cams with major increases to mid and top end power. These will pull right to rev limiter without any signs of power loss and would keep on pulling past if the limiter if it wasn't there. Modest loss of low end power. Engine starts very hard I believe due to the wild lobe center changing timing of the decompressor on the exhaust cam. Engine has almost no compression when kicking. If decompressor is removed, there is too much compression to start. Decomp pin may be able to modified and shortened to give proper compression to start. These cams would work best with a bigger carb than stock, good port work, and better ignition and open exhaust. Gave the increase I was looking for at the expense of low end power and starting.

Hotcams Stage 2:

These cams state stock valve springs can be used, but I already had better ones installed so they stayed. These are sold as a mid and top end cam also. Starting is back to the way it was with the stockers. 1-2 kicks always. Quality is top notch, impressive being half the price of the graves cams. Power is awesome with these cams. Power down low is not quite as strong as the stockers but still very torquey and pulls into a huge midrange and top end pull. For how much milder these cams are then the graves(webs) they make some impressive power. They sign off just before the limiter, and i mean just before. The power is strong enough through the curve that I was able to drop a full tooth off the rear and still hit limiter going into the turns. These cams I would say compliment the stock engine making the most power out of the stock equipment. I'd recommend these for flattrack, sumo, dune climbs, and drag racing. Not as strong off the bottom as the stage one cams, but very impressive for the money.

next week I am going to try a 41mm FCR off a CRF and see how the engine reacts. If anyone has any questions I'd be glad to help!

[2000 xr650r]

Thanks for the good writeup, very usefull info.

[rufusz]

As previous poster, just wanted to say thx. Such info is great value

[grayracer513]

What exhaust system are you running? Did you work out the optimal jetting for each combo, or just drop them in? My '06 does not behave the way you describe, with the sharp drop in power, until somewhat later in the RPM scale.

[KZaj43B]

Gray, the exhaust is the tail portion of a complete Yosh TRC system, although no longer with the Yosh head pipe. I have a FMF Sx powerbomb headpipe and a factory titanium one currently, and with the stock cams I also tried the stock '06 factory muffler. Jetting was changed and fine tuned for all setups, including different needle profiles and pilots/mains. The drop in power isn't like it falls on its face, but at 60+ mph you can feel when the power stops increasing and starts to fall off. Bigger tracks were worst with the stock cams. Factory head pipe seems to extend the power farther using stock cams, while I can get great top and good bottom using the hotcams with a FMF pb headpipe and yosh tailpipe. I seem to think the '06 cdi leaves some more power to be tapped into and a dynatek ignition will be on its way this winter on top of installing the 41mm FCR this week.

[grayracer513]

The bigger carb helps quite a bit. Not sure exactly how big Ron Hamp goes with them, but it really wakes them up.