402EX to 416EX

[Skeldaw]

Hello guys, I want to make my 402ex a 416ex in the following months but I have few question, What do I will have to do to make it reliable? Do I will have to change the crank bearing or anything else? I want to put a HotCam stage 2 so how much do you think that gonna cost me in total?

[CJM]

Dont need to do it unless yours is smoking and burning oil. Bore size doesnt add power, compression does. If anything you might gain 1-2hp at most from going up from stock to a 426.

If you do need to bore it, go tot he next size, 407.

11:1 is the preferred compression ratio. Stage 2 hotcam is also a very good cam. Will change the power curve a bit and add more mid to topend power.

300 bucks approx to buy the parts.

[Zakradu398]

HotCam Stage 2 is $110 through ebay. If you go high compression I would do the GT Thunder Headstuds which I believe is less than $100 with them putting them in.

Personally, if your at 402 which I think is 85.5mm, try to go to just 86mm if possible. That will bring you to a 406/407.

With a high comp piston I DO NOT recommend the Stage 1 HotCam, My friend has it in his 11:1 and I hate it bad, Mine on the other hand doesn't have quite as much bottom end but a ton more top.

I have a Wiseco 11:1 piston and it hasn't given me any trouble so far. Other people like JE pistons but I've never tried them.
Stay away from Namura and Pro X. I wouldn't run those in a 4 stroke.

This is a damn bulletproof set up, just make sure your connecting rod has no up and down movement and very slight side to side. Also checking for scorch marks from things getting hot, It'll look like discolored, dark metal.
Hope I could help some.

[Blodg]

Zak, thanks for the comparison between the hotcam stage 1 and stage 2. I am trying to decide between the two along with an 11:1 piston and was thinking of going stage 1 because I do mostly woods riding and I like a motor with a lot of bottom end. But others have said the same thing as you in that stage 1 falls off so much on the upper end that it is almost not worth it.

Where would everyone recommend buying a piston and cam from? EBay had good prices, is that where you guys have bought from?

[AtvKid4Eva]

Wiseco and JE are both good pistons. The best place to buy them is wherever they are cheapest. Probably Ebay. I have found the stage 2 hotcam to be the best all around cam out of the three.

[slightlybent47]

My 416 with stage 2 cam, medium port 12.5 to 1 and a 450 carb has been very reliable.
Going on 4 years racing on this build and she still runs perfect!

[Zakradu398]

Forgot to mention, I haven't done it yet but I recommend the '03 CRF450 timing chain. Same size as stock 400 but beefier links. I highly recommend red loctite on the cam sprocket bolts, I've heard of some hot cams letting the sprocket go.

[CJM]

Using red loctite means you will have a hell of a time getting it off period. Use blue, holds up just fine.

[Zakradu398]

Red needs heat. Not going to hurt it and worth it IMO althought I'm sure you'd be okay with blue.

[CJM]

Originally posted by Zakradu398
Red needs heat. Not going to hurt it and worth it IMO althought I'm sure you'd be okay with blue.

Oh I agree, it aint gonna hurt it. But man it takes some good heat to get that crap off.

[Zakradu398]

Sure is hell lol. There was Red loctite on the front rotor of my yz. Had no clue it came like that from the factory, sure was fun getting those out :mad: