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Discussion Starter #1
I read a post from edgerat, a poster who seems to have his hardware on correctly, saying that when doing the cam mod, you will get even better performance if you replace the yfz exhaust cam with a YZ cam and then rotate one tooth clock-wise. Did I understand that correctly, and if so, can someone explain to me why? I don't dispute this, just want to understand why. Also, what are the possible ramifications such a clearance within the motor, reliability, etc. I'm interested in making this chance and only want to have to open up the motor once.

If there is anyone out there who has done this mod, and/or has changed over to the YZ cam as well (edgerat), please email me directly as I have many questions!!!! 8|

Thanks in Advance!!!!!
 

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You rotate the stock cam.
Or, you can put in the YZ450F cam, and you line up the timing marks the way they should be.

If you retarted the YZ450F cam by one tooth, you will most likely cause serious engine damage due to valves hitting the piston (you want to avoide doing that ;) )
 

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NOOOOOOOOOOOOOOOOOOOO, when you do the cam mod with the stock YFZ cam you rotate it. When you install the YZ cam you line it up the same as stock. I used NH's instruction to do both so you can trust him as well.
 

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Originally posted by velocity111@Sep 24 2003, 06:04 PM
I read a post from edgerat, a poster who seems to have his hardware on correctly, saying that when doing the cam mod, you will get even better performance if you replace the yfz exhaust cam with a YZ cam and then rotate one tooth clock-wise. Did I understand that correctly, and if so, can someone explain to me why? I don't dispute this, just want to understand why. Also, what are the possible ramifications such a clearance within the motor, reliability, etc. I'm interested in making this chance and only want to have to open up the motor once.

If there is anyone out there who has done this mod, and/or has changed over to the YZ cam as well (edgerat), please email me directly as I have many questions!!!! 8|

Thanks in Advance!!!!!
I'm running the YZ exhaust cam - well I was. Right now, my YFZ engine is nothing but broken parts. Shit!
 

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Discussion Starter #5
I gatcha, either rotate the yfz cam, or change it to the yz cam with the same timing. Between those two choices which one is better, and why? From the 3 people who have replied, you all did the yz cam with the stock timing - would that be the better choice?


Selector - is your motor in parts cause of the cam change, or from something else?

I really appreciate your input on this, as I'm planning on doing the mod this week. :rock :rock :O
 

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Selector seized his motor last weekend. No answer on what the cause is. I did the YZ exhaust cam for one reason, I would be assured the decompression pin was in the correct placement. Other than that there is no reason to do the YZ exhaust cam. It is only a 106 bucks from Bob and Magnolia Yamaha so I did it to see and it worked out better than I hoped. My seat of the pants dyno tells me the YZ cam makes more power all over versus the cam mod but I cant prove it.
Isaac
 

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I have only done the cam mod (stock YFZ cam rotated), so I cant say if there is a difference between cam mod or using the YZ cam.
I can say the performance difference is well worth the 11/2 it takes to do the mod, or replace the cam.

Ive had mine done now for 3 months, and I have never had a problem starting it. I dont think that rotating it is effecting the decompressioner at all, or enough to cause any problems.

edgerat knows his stuff, so if he says there is a difference over the YZ cam, vs. the cam mod, I would trust it to be true. I chose to do the cam mod becuase its free!!

Either way, you will be happy you did it.
 

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Originally posted by velocity111@Sep 24 2003, 11:11 PM
Selector - is your motor in parts cause of the cam change, or from something else?
My failure was due to the wrist pin. This cam mod is an old trick - tons of WRs running it. Don't worry about it - just get it done.
 

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Discussion Starter #9
Gents, thanks for all the input. I'm going to do the yfz cam mod, but have one final question. As I've just picked up the quad and it has a total of about 20 min ride time / break in time, should I break the engine in first before doing the cam mod? The dealer said to run the thing for about 5 hours, in 30-40 min pieces and let cool down for that long in between. After that, change oil and filter, then I'm ready to roll. This jibes with what I've read on this site, anyone have any other suggestions??

Thanks again for the straight poop!!! :yfz
 

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Bear in mind that if you do anything inside your engine, regardless of how proven it is, your yami dealer and Yamaha will f you if something goes wrong during the warrantee period and they know you've been in there. I have just lived it. Although in my case, the dealer did everything. Neither yami or the dealer would stand behind their work.

It's for that very reason I'll never purchase another yami again.

I'll be back together and improved soon.
 

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Has anyone verified the difference between the YZ cam and doing the mod on the stock cam? I've heard so many people who swear that the stock YFZ exhaust cam turned 1 tooth is the same as the YZ cam with the timing marks lined up. I know what edgerat said and I do believe him I'm just wondering if anyone has any cold hard facts about the differences.
Thanx, Diggler
 

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as being a engine builder myself, we have taken both the yfz and yz cam measured them quite extensively. and there is absolutely no difference in the two cams. they have exactly the same lift, same duration, same lobe separation,same everything except the timing marks. and if you set the yfz cam one tooth negative you will have exactly the same cam as the yz bike.
i hope this answers anyones questions.


SELECTOR:
sorry to here about the recent mishap with the YFZ. i know you think i'm a dumbass or whatever, but i would appreciate it if you could give me a little info on what exactly happened to your motor.
if you wouldn't have blew me off so fast as a liar or a bullshitter, you could've got ahold of me and i could've helped you with warranty.i'm a master certified yamaha,kawasaki,honda and polaris tech. i also work for a bid dealership, and i'm sure i could've got your motor fixed for free.
if theres anything i can help with let me know. you know how to get ahold of me. peace.
 

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Originally posted by killerkx327@Oct 16 2003, 08:26 PM
SELECTOR:
sorry to here about the recent mishap with the YFZ. ...i would appreciate it if you could give me a little info on what exactly happened to your motor.
One of the circlips holding the wristpin came out as did the pin and all hell broke loose. I just got my cylinder back from Millenium yesterday - tons of wall still there. I'm only waiting on a couple of gaskets and we'll be back and running next week.

Parts purchased/fixed:

piston
cylinder
crank/rod assembly
valves

Got the wiring system cut back to only the basics. I'll wait until the machine in operable again before finishing the electrical. I want to test a few things out and possibly eliminate more.
 

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Originally posted by Dill@Oct 17 2003, 07:23 AM
had you ever had the engine apart before this happened selector?
The dealer installed the 13:1 piston before I took delivery of the machine - so yes. Everyone I've talked to and that has seen the damage ALL agree that the failure was @ the clip. The dealer didn't take an ounce of responsibility for a thing.

Funny thing is, I already had the larger piston and the cylinder needed to get bored/plated anyway. I managed to get a free crank/rod and I'm really not into the repair that much considering I was gonna go big bore anyway.
 

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sounds like the dealer re-used the stock circlips and didn't install new after replacing your piston...

you could check with Yamaha and determine if the dealer ever had new circlips sent to them from a Yamaha warehouse for proof if your looking to conclude who is liable.
 
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