another article

[skyhook]

I'm the Al Taylor that built heads for Cale Yarbourgh, Bill Elliot and Ray Evernham. Never heard of Tk enginering. T+l engine development in Stanfield N.C...Loydd Mcleary is the owner  and KT engine development in Concord N.C...Kenney Trouhtmen is the owner, I've worked for both of them. I have also worked for Keith Dorton, David Vasselnuck  and have done contract work for half a dozen cup teams. I have been building and racing  cars and motorcycles for 40 years. Have set national records won championships with cars, motorcycles, dirt asphalt, snowmobiles, motocross, roadrace etc.

Why do's he want to build a undersquare motor then want to spin it to 7000 rpm? All the head work on the planet won't help that. 4500 fpm is a good number for safe piston speed at 7000 rpm...piston speed is 4958 fpm. A cup motor will run at 4700 fpm at 9000 rpm and all the parts are thrown out after the race. They have a much shorter rod, better alloy pistons, and a plain bearing crank! The roller crank gets real pissed off at 7000 and up. Ok for short bursts, but cylinder fill is so poor at that fpm you junk your parts for nothing. Lets talk about piston speed and cylinder filling. Long stroke=fast piston...poor cylinder fill...short stroke=slow piston, better fill. I would use custom build pistons for this deal...Wiseco uses 4032 alum in their shelf pistons...with this kinda speed 2618 is a must!! 

I have a baseline cnc program.

for this deal I would want to weld the ports and raise the intake. This of course requires a lot of other work!

11 to 1 is about the max you run on pump gas. Unless you can run higher octane.

I would suggest titanium valves depending on the amount of street miles  I use Del West when people have the money. Ferrea and Kibblewhite for stainless or cheaper titanium.The titanium would require beryllium seats. I use C.H.E. guides and use a intramike and sunnen hone to size them. Mostly comp and psi valve springs with P.E.P. titanium upper retainers. If not titanium valves than I suggest 7 m/m Depending on lifters...with stock lifters and 5/16 stem stainless valves I do not go over 160 to 170 psi on the seat...much more and you overcome the hyd pressure. Depending on the spring  260 to 320 at full  lift. With solids we would bump that up. 7 m/m  and titanium would be different. For street motors I have had good luck using lower pressure on the exhaust side as it is a lighter valve and needs less pressure to control it. As a result fewer problems with noisy lifters.   

[fuzznut5197]

I don't think it's fair to condemn or rip apart people based on what they wrote, especially if they can't defend themselves. Not nice. 

[Admiral Akbar]

"Not nice. "

Agreed. Max

[skyhook]

sorry, maybe my jokes are a little too over the top...feel like the purpose of this forum is for learning and that's the intent of these articles

[Don D]

Sorry for the philosophical answer, not tech, and I am not discouraging you just give my 2c

Talented guys build these beasts and make them run. The leaders in the industry, a few that comes to mind is Ron Dickey and Reggie Sr.
Dewey used the term "ham and eggers" to designate the average Joe and I field lots of calls from those types of guys and most just want a big smile when they roll-on. Most don't ever top 5,000rpm. Many think they "need" more when in fact they "want" more or are reading too much on the internet. Most have not riden a bike with a big motor that makes 130/130 and if they did might get a charge out of it but either not have pockets deep enough to get that or even if they do day after day would be just as happy with a torquey 103-107" with reasonable cam and compression.
Assuming Al Taylors ideas will work why go there, the 7000rpm+ Vtwin big bore short stroke etc.? I really wonder what motivates the effort and expense.
It is human nature for some to be and do different, be trendsetters so to speak. This effort may be rewarding as far as from a personal challenge perspective but the marketability would not be there (you did previously mention you were a business partner), and even though a guy may build grand dyno shootout and drag race stuff it doesn't assure they can put together affordable, reliable street packages. In some ways these are more difficult to package. Many of these ham and eggers are fussy and want it all so to speak, for low bucks to boot.
If you are serious about this venture and it is not just a publicity grabber I would treat the VTwin as 2 individual 1 cylinder motors, IR carburetion or EFI, and if this motor is going to regularly rev over 7k consider eliminating the roller bearings and use forged rods, plain bearings, forged 1pc crank.
Hope you and Al have deep pockets
As a side note as a starting pont either the V-Rod or Sportster have advantages IMO for this bullet and remember cutting edge is close to bleeding edge.
Good luck and give us updates.

[Admiral Akbar]

sorry, maybe my jokes are a little too over the top...feel like the purpose of this forum is for learning and that's the intent of these articles

Got a better idea.. Lets go pick on Donny... 

Al is talking bout building a fast street bike based on HD.. I'd bet it's smoke but...  Not sure I'd use Titanium valves, they don't last.. You can spin a HD motor to 7000 no sweat.. Wouldn't do it all the time though.. I called Wiseco a couple years ago and they said all their HD pistons were 2618, some of the 2 stroke pistons were 4032.  You can spin a roller crank to 13.5K no sweat but the parts had better be smaller, stroke shorter.. ala crf250....

Max

[skyhook]

funny you should respond, bruce...were your ears burning?...just got off the phone for 2 hrs with john sachs...he thinks a lot of you

[ejk_dyna]

<<just got off the phone for 2 hrs with john sachs>>

...i hope you bought something from him...

[skyhook]

haha ed...I originally called john to ask a question about milling domed 110" pistons, but we just ended up talking about every subject under the sun...from his son's racing efforts, various approaches to bulding motors, which builders have the knack, etc, etc...must say I was really impressed with his knowledge, experience, and attitude...couldn't get a word in edgewise, but really didn't want to, the guy is so smart...kinda like talking to reggie, except I could actually follow what he was saying lol

don, thanks for the reply...funny thing is that in the article al was responding to a question from a guy who wanted to build a 3.875 x 4.25 motor that would pull to 7k rpm...and al was trying to discourage the guy from pursuing such a high powerband...really my fault for drunk-typing the original post and being so vague