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Cam Question

16 posts in this topic

I got to thinking about this... I have a 02 Wr426 and was wondering when i rebuild my motor this summer if i decide to go to a Hotcams setup for a wr i cannot yz time it correct... also if i go w/ a yz450 cam w/ the auto decomp do i use the YZ timing marks to get yz timing or do i need to back it up one tooth.. or will that throw the auto decomp off... Just got to pondering on this.. i would ASSSUME that w/ the yz cam you would just use thier timing marks and time it like you would the wr by lining up the marks... but i could be wrong.. :) just thought i would ask

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I didn't know your '02 had auto decomp.

Considering the valve problems you can get yourself into, I think I'd either run stock WR, or stock YZ.

Unless, of course, Hotcams will rebuild your motor again when the valve train explodes.

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I'm pretty sure he's talking about using a yz cam from the 450 which has the auto decomp....

You can obviously use this setup and there are very specific instructions in the YZ forum for this. If you want yz timing then use the yz cam. If you want wr timing then use the wr cam. I won't re-hash all of it here. Look up the 450 cam mod. There are many who have done it and can tell you how to align the cams. :)

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You can buy 4 different setups from Hotcams

1- WR cam without auto decomp

2- WR cam with auto decomp

3- YZ cam without auto decomp

4- YZ cam with autodecomp.

You want autodecomp: 2 or 4.

You want to YZ time: leaves you with only one option: 3 or 4

You want both: 4

If you don't care about the higher performance of a hot cams , you can just throw a YZ450f exhaust cam in there and things should be fine.

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thats what i was wondering... if i use the yz450 cam w/ autodecomp just use the timing marks on that cam to time it and all will be good.. :)

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Hi All,

Maybe I can shed some light on this. If you want to put the stock 450 cam in (which you can do), do like jchantzWR400F, said "If you want yz timing then use the yz cam. If you want wr timing then use the wr cam.".

If you want a Hot Cam, we offer an exhaust cam specifically for the 426 that has a decompressor styled from the 450, but has the gear made for the 426.

If your only goal is easier starting, then you can go with just the exhaust. If you want a performance gain, then you would need the intake also.

We offer one set of cams for the 426, and another set for the 450, and they should not be interchanged. We do not offer two versions of the timing. We do not use YZ timing, or WR timing. Our lobe centers are different then either the YZ, or the WR, so we have Hot Cams timing. It will have closer characteristics to the YZ though, for comparison.

Dan_from_HB,

What is it that you mean by this? :)

"Unless, of course, Hotcams will rebuild your motor again when the valve train explodes."

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so what your saying is that if i want to use hotcams w/ my wr426 which i probably will... since i will have other performance upgrades (ported head, high comp piston and what not) than i should use the wr set w/ autodecomp but it will perform like the yz... or should i just get the yz set??

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If you want to use Hot Cams on a 400/426, we have one option 4002-1IN (intake), and 4035-1E (exhaust). We don't have a set for a WR, and another for the YZ. We have one set for both. Our cams for the 400/426, where designed for more midrange, and top end on the YZ. If you have a WR, then these cams will make it act more like a YZ. I hope that helps.

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Hi All,

Maybe I can shed some light on this. If you want to put the stock 450 cam in (which you can do), do like jchantzWR400F, said "If you want yz timing then use the yz cam. If you want wr timing then use the wr cam.".

If you want a Hot Cam, we offer an exhaust cam specifically for the 426 that has a decompressor styled from the 450, but has the gear made for the 426.

If your only goal is easier starting, then you can go with just the exhaust. If you want a performance gain, then you would need the intake also.

We offer one set of cams for the 426, and another set for the 450, and they should not be interchanged. We do not offer two versions of the timing. We do not use YZ timing, or WR timing. Our lobe centers are different then either the YZ, or the WR, so we have Hot Cams timing. It will have closer characteristics to the YZ though, for comparison.

Dan_from_HB,

What is it that you mean by this? :)

"Unless, of course, Hotcams will rebuild your motor again when the valve train explodes."

Here's my take: I was half-joking, but only half-joking. Not that I have anything against Hotcams specifically, but I'm not a fan of attempting to "upgrade" performance on a motor as well thought out as the late model 4 strokes from Yamaha , particularly on internal modifications. No one has put more R&D money into dirt bikes than they have. No one knows the limitations of the motors as well as they. These motors ask a lot of the valve trains as it is. Pushing the performance envelope further is asking for trouble, IMHO.

For example, they have recenly gone to titanium valves to squeeze the tiniest bit of extra performance out of the top end. And look what a change that made to the service intervals.

Another example: 420 kits were popular for a while for the WR and YZ 400's. That is, until Ty Davis finished only about 1/2 the races he entered one season due to engine failures from pushing the envelope just a little too far.

The point is that running cams with increased duration and/or lift in a motor that is already designed to operate with max performance, while maintaining reliability, is a risk I wouldn't want to take.

Swapping throttle stop screws, silencers, headpipes, air filters, and even going to YZ cam timing is one thing. Looking for increased performance in an already optimized valve train is another.

I realize some are willing to push the envelope, it's just not for me.

Sorry for the long-winded response.

Dan

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My apologies for my first post of this thread. What I had understood form the HotCams website was that there was specific cams for YZFs and different ones for WRFs (always talking about 400s and 426s). My mistake. :)

What I undestand now is that HotCams sells a 400/426 exhaust and intake cam and that they are the same for the YZ and WR models.

Also, you seem to mean that there is no power improvement by using only the exhaust HotCam, and that the intake cam is the one responsible for power improvement, is that right?

Thanks!

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"Also, you seem to mean that there is no power improvement by using only the exhaust Hot Cam, and that the intake cam is the one responsible for power improvement, is that right?"

Close. They where designed as a set, and you would need both cams to get the advertised gains. If you only want it to start without having to use the manual decompressor, you can install just the exhaust cam. The exhaust alone just wont show an improvement with out the intake cam that compliments it.

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I don't know the long term reliability of a bike with Hot Cams but I put them in a YZF250 with 262 kit from Eric Gorr. The bike really goes. Gorr told me not to worry about the reliability, he has noticed no difference. He said their stuff is pretty well thought out.

The cams were very well made, I didn't have to reshimm any of the valves.

I may try a set in my WR450.

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"Also, you seem to mean that there is no power improvement by using only the exhaust Hot Cam, and that the intake cam is the one responsible for power improvement, is that right?"

Close. They where designed as a set, and you would need both cams to get the advertised gains. If you only want it to start without having to use the manual decompressor, you can install just the exhaust cam. The exhaust alone just wont show an improvement with out the intake cam that compliments it.

I see. Very logical. Thank you much for joining in and sharing these informations with a novice in motorcycle mechanic. :):)

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