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banda

Piston,cam options - WWYD?

4 posts in this topic

I have a third-hand 2000 YZ426F.

Presently it has a high compression Wiseco piston, a stock exhaust cam, and +12oz Steahly flywheel.

I race amateur supermoto, amateur TT scrambles, and do some trail riding.

It carburets perfectly, and has good mid range and top end acceleration. I am very happy with its power output.

I am not happy with flameouts - while my bike starts on the first kick, cold or warm, it will not bump start, and if I get too happy on the rear brake coming into a silppery corner, that's all she wrote. It dies. The heavier flywheel lets me bog it a little bit more before it dies, but still when it dies, that's it. I'm kicking it if I want to rejoin the race.

My plan to take care of the flameouts is to do the '03 YZ450 cam swap. I have my cam on order.

Here's my question:

Should I also consider going to a stock piston? I have one, and I have new rings for it. I have no idea how many hours are on the Wiseco that's in there.

I would rather ride without the risk of flameouts than have the ultimate top end punch. What would you do? Keep the high compression Wiseco, or go back to stock? Will the '03 cam plus the high compression piston make my bike a monster? Will I need something other than premium pump gas?

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When I took the bike apart to install the cam I would pull the head off and see how the piston thats in there looks.It it looks pretty bad I would swap it out for the stock piston.

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The 450 cam should solve your problem by provide the auto-decomp. You can technically bump start your bike using the decomp lever. I've had to do it a couple times for my bike. But you have to be careful doing it this way as you could end up bending your valves.

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Well, I bought a '03 YZ450 cam, installed it, left the Wiseco high comp piston in, and everything seems hunky-dory. My bike is a breeze to start, firing on the first kick, and doesn't stall hard like it used to. I have locked the rear wheel in the slippery stuff, and it fires right up if I let off the rear brake while I still have some speed.

The cam mod did the trick. I am much happier with my 2000 YZ426F now. Thanks.

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