- Aug 3, 2004
- 1,003
- 0
This thread will be an attempt to take all of the information regarding 444 engines that have been aquired thus far, as well as some new things to test, and build a yzf444 with the biggest fattest torque curve ever. I have read every thread that I could find about yzf tuning and yzf444 specifics that I can find, so bear with me if I ask a question that I may have not read the answer to.
The plans:
1) 97mm bored replated cyl
2) 13.5:1 97mm wiesco
3) ported head by Rich @ EG
4)a custom oversize headpipe that feeds a custom reverse meg
5)stock intake cam LCA 104 ( 5 degree advance)
6)stock 450F exh cam
7) 4-stroke specific race fuel
8) stock valvetrain
Now the plans in detail.
1) The 97mm Cyl. is a done deal, no questions about that. :yeehaw:
2) I think that Rich was previously lightening pistons for the yz444 to within a couple of grams of the stock piston weight, if that is correct, I will be using a lightened Hi-Comp piston.
3) How much will the flow of the intake and exhaust charges benefit from a reshaping of the combustion chamber given that the head how has an extra mm of material that isint doing anything but being flat? I am guessing that an unshrouding of the valves would make the charges more willing to flow smoothly into/out of the cyl head. How much is there to be gained on the exhaust side of the head? (if it were to flow directly into an oversize header that matches the exit diamater of the exh. port)
4) I have e-mailed Rich about meg design specs and will post his reply, as well as my questions, when I get the response back. I was thinking that a headpipe with a minimum ID of 1.75" would flow very well with the big bore. The meg will be designed first and foremost to produce a huge torque curve and flow well up into high revs. This will make it very loud and I might not be able to silence it very much, if at all, but that is not the goal of this project. :p
5) I am going to have a local machine shop (that I trust) advance my stock intake cam by 5 degrees. That makes the lobe center angle (LCA) 104, according to my research, this seems to be the best Intake timing for a motor such as the 444..
6) I have been using a 450F auto-decompressor cam in my 426 for over a year now and it shows no more wear to any part of the sprocket or cam than my stock 02 cam does. I Will be using this cam in the 444, but possibly with a different LCA. I dont know what the LCA is with this cam. Should the exhaust cam be advanced like the intake cam will be, or should the exhaust cam be retarted? The way I picture it in my mind is that after adjusting the intake LCA to 104, I now have 5 MORE degrees of valve overlap, but if the exhaust cam were anvanced by 5 degrees to make up for that, how would that effect the combustion?(since the valve would be opening 5 degrees earlier) Basically I dont know what I need to do to the exhaust cam to make it correctly compliment the Intake 104LCA with the 97mm piston. I need help on this one.
7) The search continues for a race fuel that will work well in a high-comp, ultra-short-intake tract thumper, that will not require me spending a fortune on race fuel for the season. What are everyone's best opinions, in cluding our resident fuel guru Rich, on using VP U4, which seems to be the bext Oxy fuel for it's price. But if another fuel is significantly better than U4, the wallet will just have to take the hit.
8) For the valve train I plan on using either all stock parts (they are so cheap, who cares if i have to replace them). I will not be using the Ti-Valves when they need replacing, instead I will be installing steel valves from a pre-02 426f. This choice is based purely on cost, since the steel valves should last as long as the Ti valves and I doubt that a measurable power loss will be had by using the slightly heavier steel valves vs the Ti valves. I may upgrade the springs and retainers using the kibblewhite spring kit though, it comes with Ti retainers :aj: BTW, what would oversize valves combined with the above setup do the the torque/HP curve? I hear that the 97mm piston creates a sweet spot with the stock valve size and intake flow velocity... :think: Rich said that didnt he?
I'm sure that I have forgotten something, and am open to any other mods that will help me reach my goals. Time to go eat some food and do some more thinking on this one...
The plans:
1) 97mm bored replated cyl
2) 13.5:1 97mm wiesco
3) ported head by Rich @ EG
4)a custom oversize headpipe that feeds a custom reverse meg
5)stock intake cam LCA 104 ( 5 degree advance)
6)stock 450F exh cam
7) 4-stroke specific race fuel
8) stock valvetrain
Now the plans in detail.
1) The 97mm Cyl. is a done deal, no questions about that. :yeehaw:
2) I think that Rich was previously lightening pistons for the yz444 to within a couple of grams of the stock piston weight, if that is correct, I will be using a lightened Hi-Comp piston.
3) How much will the flow of the intake and exhaust charges benefit from a reshaping of the combustion chamber given that the head how has an extra mm of material that isint doing anything but being flat? I am guessing that an unshrouding of the valves would make the charges more willing to flow smoothly into/out of the cyl head. How much is there to be gained on the exhaust side of the head? (if it were to flow directly into an oversize header that matches the exit diamater of the exh. port)
4) I have e-mailed Rich about meg design specs and will post his reply, as well as my questions, when I get the response back. I was thinking that a headpipe with a minimum ID of 1.75" would flow very well with the big bore. The meg will be designed first and foremost to produce a huge torque curve and flow well up into high revs. This will make it very loud and I might not be able to silence it very much, if at all, but that is not the goal of this project. :p
5) I am going to have a local machine shop (that I trust) advance my stock intake cam by 5 degrees. That makes the lobe center angle (LCA) 104, according to my research, this seems to be the best Intake timing for a motor such as the 444..
6) I have been using a 450F auto-decompressor cam in my 426 for over a year now and it shows no more wear to any part of the sprocket or cam than my stock 02 cam does. I Will be using this cam in the 444, but possibly with a different LCA. I dont know what the LCA is with this cam. Should the exhaust cam be advanced like the intake cam will be, or should the exhaust cam be retarted? The way I picture it in my mind is that after adjusting the intake LCA to 104, I now have 5 MORE degrees of valve overlap, but if the exhaust cam were anvanced by 5 degrees to make up for that, how would that effect the combustion?(since the valve would be opening 5 degrees earlier) Basically I dont know what I need to do to the exhaust cam to make it correctly compliment the Intake 104LCA with the 97mm piston. I need help on this one.
7) The search continues for a race fuel that will work well in a high-comp, ultra-short-intake tract thumper, that will not require me spending a fortune on race fuel for the season. What are everyone's best opinions, in cluding our resident fuel guru Rich, on using VP U4, which seems to be the bext Oxy fuel for it's price. But if another fuel is significantly better than U4, the wallet will just have to take the hit.
8) For the valve train I plan on using either all stock parts (they are so cheap, who cares if i have to replace them). I will not be using the Ti-Valves when they need replacing, instead I will be installing steel valves from a pre-02 426f. This choice is based purely on cost, since the steel valves should last as long as the Ti valves and I doubt that a measurable power loss will be had by using the slightly heavier steel valves vs the Ti valves. I may upgrade the springs and retainers using the kibblewhite spring kit though, it comes with Ti retainers :aj: BTW, what would oversize valves combined with the above setup do the the torque/HP curve? I hear that the 97mm piston creates a sweet spot with the stock valve size and intake flow velocity... :think: Rich said that didnt he?
I'm sure that I have forgotten something, and am open to any other mods that will help me reach my goals. Time to go eat some food and do some more thinking on this one...