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slipnslide

Anyone try:Hotcam autodecomp in WR400?

15 posts in this topic

How well does the Hotcam auto-decompression exhaust cam (Part # 4035-1E) work on a WR400? :banghead: Does it hurt the bottom end torque?

I want to install it bad, but on the Hotcam website the description of the cam says "Excellent midrange, and top end power increase. This cam works best with 95mm bore (426cc) or larger." That makes me wonder if it might actually hurt the performance a little.

I have not found any old threads on TT about that cam in a WR400 so I hope someone out there has tried it. If there is a thread about it, can anyone direct me to it?

Also, can that cam be installed with WR or YZ timing?

Thanks for any information y'all have! :banghead:

http://www.hotcamsinc.com/catalog.asp#4035-1E%%Yamaha%%YZ/WR%20400/426%%1998-2002%%Auto%20Decompressor%20Exh%20Cam

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When I put the hot cams in my 426, I did a lot of searching for info and came across a thread from either late '02 or early '03 discussing this issue. The hot cams guy was posting here regularly during that time as they developed the auto decompressor cam for the 426...in one of the posts he said the cams would work fine in the 400s...unfortunately, I can't find the post right now...but, if you look for posts from "HotCams", you'll find about 250 posts, and it's gotta be in htere somewhere...also, if you read some of his posts, he refers to the 400/426 cam, implying it's fine for both.

Here's a thread discussing results from a YZ400 inst'l, as far as hotcams are concerned, the WR and YZ are the same.

http://www.thumpertalk.com/forum/showthread.php?t=169681&parentpage=5&highlight=hot+cams

Hot cams don't use either WR or YZ timing. They set their cam timing to provide the optimum peformance with their profiles, regardless of YZ or WR. It's "hotcam" timing.

As far as a performance increase, on my WR426, the bottom end stayed about the same, then a moderately bigger hit at the midrange, and a huge boost in top end. Overall, a very pleasant change (even better than YZ timing).

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When I put the hot cams in my 426, I did a lot of searching for info and came across a thread from either late '02 or early '03 discussing this issue. The hot cams guy was posting here regularly during that time as they developed the auto decompressor cam for the 426...in one of the posts he said the cams would work fine in the 400s...unfortunately, I can't find the post right now...but, if you look for posts from "HotCams", you'll find about 250 posts, and it's gotta be in htere somewhere...also, if you read some of his posts, he refers to the 400/426 cam, implying it's fine for both. I'll search some more. I have sent an email to Hotcams but no response yet.

Here's a thread discussing results from a YZ400 inst'l, as far as hotcams are concerned, the WR and YZ are the same.

http://www.thumpertalk.com/forum/showthread.php?t=169681&parentpage=5&highlight=hot+cams

Thanks for that link. It sounds like the autodecomp works really well. It would be so nice to be able to bump start!

Hot cams don't use either WR or YZ timing. They set their cam timing to provide the optimum peformance with their profiles, regardless of YZ or WR. It's "hotcam" timing. That's interesting. I wonder if the timing can be altered by one tooth, as with the stock cam? If not, I don't really care. I am more interested in getting the auto-decomp feature than any power boost or alteration.

As far as a performance increase, on my WR426, the bottom end stayed about the same, then a moderately bigger hit at the midrange, and a huge boost in top end. Overall, a very pleasant change (even better than YZ timing).

Good, I want to keep all the bottom end I can. My favorite riding is chugging up gnarly hills. :banghead:

Thanks for the input. I feel more comfortable with buying one of their cams. :banghead:

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I have read that the Hotcams for the YZ/WR have an adjustable Ex Cam sprocket. I think it comes "preset" and you can alter it from there.

Good luck.

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Does this bypass the decompression lever completely? Does anyone have a guesstimate on how long it takes to install and skill level needed? Is this the only part needed? I would love to rid myself of the decompression lever for a few hundred bucks.

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Does this bypass the decompression lever completely? Does anyone have a guesstimate on how long it takes to install and skill level needed? Is this the only part needed? I would love to rid myself of the decompression lever for a few hundred bucks.

Yes, the decompress lever and cable get to be retired to your spare parts box :banghead: but you will need to buy (or make) a plug to replace the lever end at the head. It took me around an hour to make the change but then I'm ASE certified. All it takes is standard tools except the inch lb torque wrench.

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I got some very informative answers from Sean at Hotcams. I sent him two sets of questions in two emails and he got back to me in one business day or less both times. I'm impressed with their customer service. Check it out:

> >Do you have a dyno graph of a wr400 with the stock intake cam and your

> >4035-1E exhaust [auto decomp] cam?

> >

> >Your description of that cam says "This cam works best with 95mm bore

> >(426cc) or larger. "

> >What effect does if have on a stock bore wr400?

> >We do not have a dyno chart on 4035-1E, and the stock intake, because it

> >really does not effect the power enough to speak of. The only way to get

> >the advertised power, is to get the intake also. The pair of these cams in

> >a stock bore 400, will not make as much bottom end power as a 426. Let me

> >know if you have any other questions.

> >

> >Thanks,

> >Sean

>Thanks for the info. I do have three other questions.

>- If using the hotcam exhaust cam and the stock intake cam, will the low end

>power be decreaced a noticable amount?

>- Do you have a dyno chart of a WR400 with both the intake and exhaust cam?

>- I see the cams are described as YZ and WR cams. Are they installed

>differently in the two bikes? [like the stock cam which can be adjusted by

>one tooth (as I am sure you know)]

>Thanks again. It's nice to deal with a company that has knowledgeable

>salesmen.

>By just installing the HC exhaust cam you shouldn't loose any bottom end power. We have never actually had a WR in the building though. We have always tested on YZs. Then some of the engine builders usually give us feedback on how they do in the WR. For the most part, it turns a WR, into a YZ, with more mid and top.

>Our cams should be installed the same way in the WR, as they would in a YZ, and you don't want to advance it, or retard it, one tooth with our cams. We have placed the lobe centers where we wanted them to be, so they should be timed according to the marks. Thanks for the positive words. If you come up with anything else, let me know.

>

>Thanks,

>Sean

I found the above info. very useful. I'm planning on getting the exhaust cam for sure because I don't think There is much risk of losing low end power (which I love) and I really want the autodecomp feature. I hope this is useful to y'all!

PS- Birdie was right on about the ex cam timing! :banghead: Thanks for your help. :banghead:

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Don't worry, you're not going to lose any low end. Unless you go messing with different pipe configurations.

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For what it's worth, I can't say enough good about Hot Cams , both the product and the company. They are responsive to both phone and e-mail querries, very knowledgable, and very helpful. As with cars, horsepower for dollar, cams are about the best performance mod you can make, and the HotCams do a great job of boosting performance while maintaining ridability.

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Installed a set (intake & exhaust ) of HotCams in my 2000 WR400 and took it out for a shake down run today.

I'd say the bottom end is still good but I didn't attack any slow hill climbs to verify that 100% but I felt no loss. The mid to top end power is a noticeable gain. There doesn't seem to be much of a power hit for me. It felt nice and linear.

Decomp is sweet. No more "procedure", just kick and go!

Install was kind of a pain in the rump because I don't own a shim kit and had to wait a day to go get the replacement shims. Easy enough for any decent wrench. I tossed in a new timing chain for good measure.

As for the decompression lever in the head- I dropped in a $0.75 18mm expansion plug and called it a day. No need for a $30 plug that you can't see anyway. (I got this tip from someone here but don't remember the name- THANKS!)

I'd recommend the upgrade to anyone.

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from what i understand u guys are saying that even if you install the hotcams u don't have to use the decomp lever is this right if this is correct then how come, and is it as easy to start (can u kick it like any bike or still do the procedure of getting tdc b4 kicking it)

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from what i understand u guys are saying that even if you install the hotcams u don't have to use the decomp lever is this right if this is correct then how come, and is it as easy to start (can u kick it like any bike or still do the procedure of getting tdc b4 kicking it)

The exhaust cam has a auto decompress function built in so all you do is kick and go! Your decompress lever/cable etc get to join your other spare parts.

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and yes, it is easy to start. Just walk up to it, turn on the gas, chole it if it's cold and the first ride of the day, blip the throttle twice to "prime the pump", a good, swift boot, and BBBRRRAAAAAAAPPPPPP. Your good to go. The autodecomp feature, regardless of whether Hot Cams or 03 YZ450 OEM cam, is the best mod you will ever do to a 400/426.

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