YZ exhaust cam vs Hotcams exhaust on WR450

[tmckeown]

Hi,

Has anyone tested these and has some data about it ?

Timo Mc

[Justa4stroken]

Well.....I have a 05 WR450 and I tried the Hotcams, but the bike would not start with the starter with the Hotcams. I called Hotcams and talked to their tech. He had me send the cams in and they checked them and sent them back. Still no start with the electric starter. The decompression pin on the Hotcams is a lot shorter than the yamaha orginal camshaft. I felt Hotcams dropped the ball with me on the starting problem. But after a follow up I found I wasn't the only one with this issue. ?

So.....I sent the Hotcams back and ordered a set of YZ camshafts and it fired off the first hit of the starter. ?

[Matty05]

Thats dissapointing with the hotcams........ Great warning though.

How does the YZ decomp pin compare to the WR decomp pin? I don't think they are the same length by look (checked mates YZ450 valve clearances).

The YZ ex cam is cheap, no, very cheap here at the TT store. About $US90 from memory!

[tmckeown]

Hi,

I called our local head-porting and dyno people about this. They have tested hotcams and YZ cams on WR and also run those in dyno. They said that only thing what you can change with those cams is move power area up or down.

Biggets effect you can do by porting and going to JD or Vortex CDI

Timo Mc

[simon@vic]

.I sent the Hotcams back and ordered a set of YZ camshafts and it fired off the first hit of the starter. ?

set????? i was under the impression that the yz and wr had the same intake cam.................. why did you buy both? ? or am i wrong?

[Justa4stroken]

I didn't know they were the same. As for the power, the only difference I have seen is I hit the rev limiter much faster in the bottom gears. 1st is almost useless now.

[elcubeo]

Justa4stroken::

I agree. I had the same problem with the hotcams exhaust on my 2006 WR450f, I did the same thing. I sent the cam back explaining my problem, and they assured me that it was correct.

In the mean time, I used the hotcams intake cam and the stock WR exhaust, and assembled the engine this way. In my laziness, I listened to a few "expert" mechanics and salesmen and just set the timing and checked the lash.....ok looked good. fired it up....cool sounded good. Then I took it for a light ride and 0.9 miles later on my odometer, the motor went CRUNCH . Basically with the hotcams intake I had insufficient piston to valve clearance on my stock piston, and the only thing that was drop-in about this installation was me DROPPING my VALVES into the piston. I destroyed everything from my case up. Haha, its only money, right?

The lift is almost stock on the intake cam, but the duration was long enough to crash valves. Everybody tells me I timed the cams wrong, but i think can look at the pictures in the service manual ? and understand what they mean. Hotcams.....unleash the parts within....lol.

My stock WR exhaust cam and my new hotcams exhaust cam differed greatly on the decompression pin. The pin lift was about the same but the pin duration was much much less on the hotcams. The tech's explanation was that due to the increased duration of the new bigger cam, static cylinder pressure would be decreased due to the resulting increase in IN/EXH overlap. They designed the pin to have less decompression duration to compensate. I think they compensated a little too much. I shouldnt have to damn near break off my kickstart lever.

Now i'm going to have a JE 13.5:1 piston which is a full point higher compression than stock. I have been assured that with a more powerful battery, this will not be a problem. The problem is, is that i'm being reassured by the same morons I listened to last time... I'm determined to forge ahead, even though it feels like I should know better by now. You can already guess that this kinda sucked financially, but I will let you all know how this turns out, mechanically.

[Fullbore4]

set????? i was under the impression that the yz and wr had the same intake cam.................. why did you buy both? ? or am i wrong?

yes wr and yz intake cams are the same....I really don't understand why people put hot cams in when the yz exhaust cam increases performance remarkably. You only gain a horse or two with hot cams over the yz exhaust cam but hot cams also have more lift and work the springs that much harder.

[Hot Rods]

Justa4stroken::

I agree. I had the same problem with the hotcams exhaust on my 2006 WR450f, I did the same thing. I sent the cam back explaining my problem, and they assured me that it was correct.

In the mean time, I used the hotcams intake cam and the stock WR exhaust, and assembled the engine this way. In my laziness, I listened to a few "expert" mechanics and salesmen and just set the timing and checked the lash.....ok looked good. fired it up....cool sounded good. Then I took it for a light ride and 0.9 miles later on my odometer, the motor went CRUNCH . Basically with the hotcams intake I had insufficient piston to valve clearance on my stock piston, and the only thing that was drop-in about this installation was me DROPPING my VALVES into the piston. I destroyed everything from my case up. Haha, its only money, right?

The lift is almost stock on the intake cam, but the duration was long enough to crash valves. Everybody tells me I timed the cams wrong, but i think can look at the pictures in the service manual ? and understand what they mean. Hotcams.....unleash the parts within....lol.

My stock WR exhaust cam and my new hotcams exhaust cam differed greatly on the decompression pin. The pin lift was about the same but the pin duration was much much less on the hotcams. The tech's explanation was that due to the increased duration of the new bigger cam, static cylinder pressure would be decreased due to the resulting increase in IN/EXH overlap. They designed the pin to have less decompression duration to compensate. I think they compensated a little too much. I shouldnt have to damn near break off my kickstart lever.

Now i'm going to have a JE 13.5:1 piston which is a full point higher compression than stock. I have been assured that with a more powerful battery, this will not be a problem. The problem is, is that i'm being reassured by the same morons I listened to last time... I'm determined to forge ahead, even though it feels like I should know better by now. You can already guess that this kinda sucked financially, but I will let you all know how this turns out, mechanically.

The Hot Cams intake, or exhaust, or both (with stock piston) installed correctly, and timed correctly poses NO danger of valve to piston contact. If the intake valves contacted the (stock) piston, it wasnt the lobe duration at fault.

[Asgeir]

A friend of mine was installing a 4044-1E exhaust cam into his WR450F 2006.

The motor will not start with the starter motor, but starts and runs when kick started, it has not yet been driven.

I noted in the instruction video on Hotcams web that the "H" mark (looks more like an "I" tilted 90°) is used as TDC mark, is that correct ?

In the Yamaha manual it is shown as "l" (like a straight vertical line), which is correct for the Hotcams ?

In the Yamaha manual the "H" is a timing mark for a timing light.

[Mutu]

A friend of mine was installing a 4044-1E exhaust cam into his WR450F 2006.

The motor will not start with the starter motor, but starts and runs when kick started, it has not yet been driven.

I noted in the instruction video on Hotcams web that the "H" mark (looks more like an "I" tilted 90°) is used as TDC mark, is that correct ?

In the Yamaha manual it is shown as "l" (like a straight vertical line), which is correct for the Hotcams ?

In the Yamaha manual the "H" is a timing mark for a timing light.

Use the 3rd mark for TDC.

[Mutu]

yes wr and yz intake cams are the same....I really don't understand why people put hot cams in when the yz exhaust cam increases performance remarkably. You only gain a horse or two with hot cams over the yz exhaust cam but hot cams also have more lift and work the springs that much harder.

Most of the gains come from the intake side of things, once you have the YZ timing.

As for working springs much harder? The hotcams also have only a tiny bit of lift more than OEM cams, but they have more duration, which holds the valves open a bit longer.

[Asgeir]

Use the 3rd mark for TDC.

3rd Mark ???

How does that look like ?

[Mutu]

3rd Mark ???

How does that look like ?

There is 3 vertical lines. Use the last mark.

The 1st and 2nd has a horizontal line that connects the two (or The "H" mark you speak of, I guess).

[Asgeir]

On this video they show the "H" mark

http://www.hotcamsinc.com/index.cfm?fuseaction=cMedia.viewInstallationVideo&videoid=3

But the manual says to use the "l" mark.

Are Hotcams giving out wrong instructions ?

[Asgeir]

Also note on the video that the instructor says the cam lobes should point to the front and back.

But later in the video they point invards.

[trailordune]

The cam lobes need to point out and the l mark is for tdc. This should not change with the Hotcam. Sounds like their problem with the decom. pin is still not fixxed.

[Mutu]

On this video they show the "H" mark

http://www.hotcamsinc.com/index.cfm?fuseaction=cMedia.viewInstallationVideo&videoid=3

But the manual says to use the "l" mark.

Are Hotcams giving out wrong instructions ?

It won't make any difference by the way......

Use either and you won't be a tooth out!

I've also found that the valve clearances are the same at all the marks.

[SurvivorMan]

Just to clarify, on the 07 wr 450, the exhaust cam and intake cam are both diferent parts then the YZ, so i think it would be worth while to replace both cams instead of just one...that way all 5 valves have been advanced the same rate.

my question; the 07 yz cams are different from the 06 yz cams. i prefered the power delivery of the 06 to the 07.....will the 06 OEM yz cams go into the 07 WR?

[Storbeck]

I'm interested in the same question, basically which cam should I change, just the exhaust or both, and should I use 06yz, 07yz, (maybe even 08yz???) or hot cams.

Between the 06yz, 07yz and 07wr none of the part numbers are the same for intake or exhaust.

Anybody have any suggestions?? This is on an 07 wr450 with all the free mods and an 07 yz450 complete exhaust system.