Ticeman
Newbie
I haven't seen anything useful about this.
For the people that have this quad, this is the best engine mod you can do for it, period. It's all gain.
The WR and YFZ have the same cam profile as does the YZ450F. The difference is in the cam timing. Whereas the YZ use a 102.5 deg lobe centerline, the WR and YFZ use a lobe centerline of 125 deg. This promotes a softer, more manageble, power delivery. The down side is, it makes a SOFTER, more manageble, power delivery. This makes the engine rev slower and be less throttle responsive.
By retarding only the exhaust cam timing by one tooth (22.5 deg) this puts the cam timing to the proper, intended cam timing for this engine's original, design parameters. It's a free parts boost in power, time is the only thing involved to make it faster. A good mechanic should be able to do this change in 15 min.
Jetting will change slightly but, the change isn't enough that will REQUIRE you to change jets. You can take better advantage by rejetting. In stock form, YFZs like their exhaust O2 content to be in the 13.5:1 - 13.7:1 A/Fr range. All YFZs, 04-07 benefit from this change.
For the people that have this quad, this is the best engine mod you can do for it, period. It's all gain.
The WR and YFZ have the same cam profile as does the YZ450F. The difference is in the cam timing. Whereas the YZ use a 102.5 deg lobe centerline, the WR and YFZ use a lobe centerline of 125 deg. This promotes a softer, more manageble, power delivery. The down side is, it makes a SOFTER, more manageble, power delivery. This makes the engine rev slower and be less throttle responsive.
By retarding only the exhaust cam timing by one tooth (22.5 deg) this puts the cam timing to the proper, intended cam timing for this engine's original, design parameters. It's a free parts boost in power, time is the only thing involved to make it faster. A good mechanic should be able to do this change in 15 min.
Jetting will change slightly but, the change isn't enough that will REQUIRE you to change jets. You can take better advantage by rejetting. In stock form, YFZs like their exhaust O2 content to be in the 13.5:1 - 13.7:1 A/Fr range. All YFZs, 04-07 benefit from this change.
nossjunkie
Newbie
- Joined
- Feb 24, 2007
- Messages
- 1
http://www.youtube.com/watch?v=Kf5r0XjF-mY
When you said "I haven't seen anything useful about this." Did you mean it dosn't work, or no info?
When you said "I haven't seen anything useful about this." Did you mean it dosn't work, or no info?
Ticeman
Newbie
That there is no info on this site about it.
- Joined
- Apr 13, 2003
- Messages
- 21,553
- Age
- 54
- Location
- Schofield, WI
- Website
- www.totallyamaha.com
- Country
- USA
- Snowmobile
- 2020 Sidewinder SRX
Ticeman
Newbie
Took from Nov 23 to April 26 to get a single response.
Even then there weren't any comments made about what it does or why it works. Even the dadog video doesn't tell you what it does.
Even then there weren't any comments made about what it does or why it works. Even the dadog video doesn't tell you what it does.
- Joined
- Apr 13, 2003
- Messages
- 21,553
- Age
- 54
- Location
- Schofield, WI
- Website
- www.totallyamaha.com
- Country
- USA
- Snowmobile
- 2020 Sidewinder SRX
Sorry I wish I had more for you... I am a Grizz nut and have not done any work on the YFZ's
Ticeman
Newbie
I was just hoping for some technical discussion to happen. I build these and many other brands for a living and have a R&D/testing/technical services background. Just looking for some fun.
- Joined
- Apr 13, 2003
- Messages
- 21,553
- Age
- 54
- Location
- Schofield, WI
- Website
- www.totallyamaha.com
- Country
- USA
- Snowmobile
- 2020 Sidewinder SRX
I wish I had one just to play with but the sled side of things keeps me so darn busy.
