cbrian Posted January 21, 2013 Report Share Posted January 21, 2013 Hello All, I have started the process of getting a new engine for motorcycling purposes. The bike will be used not for racing but for track days (see http://www.nolamotor.com/) which is riding as fast as you can stand for 20 minute sessions, one session per hour, six sessions per day total. I do three to four track days per year. As an old two stroke guy, I want my new engine based upon the yamaha rz350/yfz350 banshee and the research for information on this engine has led me to this forum. I had no knowledge of the banshee world and what you guys are getting out of what is essentially a 30 year old design is really impressive. My goal is to have an engine that can at the very least keep up with the current 600cc four stroke bikes which have about 50 lbs/ft of torque, 115 crankshaft horsepower and weigh 400 lbs. The machine I use weighs about 330 lbs, so power to weight would be 42 lbs/ft and 108HP. I wouldn't mind power a bit in excess of these targets. What I am asking for is recommendations and please be as specific as you can as to what components, manufacturers and suppliers I will need. Crankcase - stock or ?Crankshaft/bearings/rodsTransmission modifications (need close ratio 6 speed)Clutch & drive ratioCylinders - bore & strokePower valve or notCylinder Heads & dome sizePistonsIntakeCarburetion - filtrationPower generationIgnitionLubricationCoolingExhaust - silencersand anything else you see that I've missed Main criteria for me is:Reliability - (rebuilds too often makes for an unhappy wife)Parts availability - especially pistonsBroad spread of power throughout the rev range - peaky power delivery upsets chassis too muchServiceabilityFuel used will be non ethanol pump gas 93 octane Bike run at sea level Any recommendations for engine builders would also be appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
PassionRE Posted January 21, 2013 Report Share Posted January 21, 2013 Crankcase - stock or ? ... Stock, modified for bigger monoblock arrangement Crankshaft/bearings/rods...Hot Rods 4 mill 115mm rod tz drive side brng Transmission modifications (need close ratio 6 speed) ...Banshee or RZ. would need more info. for selection. Clutch & drive ratio... 2.68 straight cut primary's 8 plate clutch and assorted hardware Cylinders - bore & stroke...... 554cc CP DM monoblock 58 stroke 78 bore modified for targeted heat production in street use. Power valve or not... not needed if pipes are designed specifically to port network and heat production is designed for this intended use. Cylinder Heads & dome size..... CP Industries with domes spec matched by builder to porting. Pistons ...Wiseco forged CP format for DM-modified Intake.... preferrably resonance matched custom , or billet aftermarket Carburetion ....- filtration 39mm Keihin wiith K&N individual 8 inch min. Power generation ... factory Yamaha RZ or Banshee with DC conversion Ignition ...factory Yamaha Lubrication... 927 Maxima Racing Castor Cooling... oversize radiator if possible on frame choice Exhaust - silencers.....Sniper custom cone set for unlimited frame fit and resonance & BMEP match Moto Tassanari reed set. Several sets of extra underwear. The ability not to gloat and smirk too much after making 600's look really slow. Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 22, 2013 Report Share Posted January 22, 2013 Not being a smartass, but if you want a 554cc or larger banshee engine, your gonna need a lot of $$$$'s. Good luck with your project Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 22, 2013 Report Share Posted January 22, 2013 Only a select few guys I know that I would trust with a gp style platform. I will pm you later in depth with details Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 22, 2013 Report Share Posted January 22, 2013 Jim Smart @ Passion Racing Rodger @ Wicked Motorsports Nate McCoy at McCoy Motorsports. John Stallworth @ JSR (several pikes peak titles) Kevin Gigot Stephen Rothwell @ Two Stroke Shop (Wayne "wobbly" wright is no longer a partner) You don't need much more then 80 HP in a light weight chassis to compete with 600's. There have been a few fellas in the sport bike scene to pop up on BHQ from time to time that took to the banshee platform and really did well. Quote Link to comment Share on other sites More sharing options...
KozyHeat Posted January 22, 2013 Report Share Posted January 22, 2013 Whats your chassis that weighs 330lbs? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted January 22, 2013 Report Share Posted January 22, 2013 Whats your chassis that weighs 330lbs? Bone stock RD400s weigh 350ish. 330 lbs with modern stuff is easily doable. I actually think his requirements are pretty easy to attain, his budget, however...may not allow it. I guess start out there. There are plenty of aftermarket cylinder setups that can be made to run well. Remember, he said these 600cc 4 strokes are putting out 116HP at the crank. Which means 90 to 100 at the rear tire, give or take. That's not that tough to attain IMO. Quote Link to comment Share on other sites More sharing options...
Paulie B Posted January 22, 2013 Report Share Posted January 22, 2013 Come on man TZ250's keep up with 600's. I think a pitfall you might run into is being able to shift the bike. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted January 22, 2013 Report Share Posted January 22, 2013 A properly prepped and cut trans (NO, not an override) should shift fine on that bike. Lack of traction is normally the problem on a banshee, std., cut or override tranny. Traction should not be an issue on a road race bike. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 22, 2013 Report Share Posted January 22, 2013 A properly prepped and cut trans (NO, not an override) should shift fine on that bike. Lack of traction is normally the problem on a banshee, std., cut or override tranny. Traction should not be an issue on a road race bike. Agreed on the on the tranny. Mine is like friggin butter. I ran it all last weekend without a missed shift and if I do it right under power I can shift it like an override.On the traction though...,, have to dissagree. Remember there will only be one tire and it's half as wide and only partially in contact with the pavement. Lotta guys out there with modern banshee cylinders(ie. Cub) and traction is the first issue most of them deal with. So, OP. If you do go that big on the motor, remember your chassis has to be just as up to par. Wider swinger conversion for a fat Michelin, custom shock, etc. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted January 22, 2013 Report Share Posted January 22, 2013 That's where the right builder chimes into play. Smooth power delivery... NOT cub type delivery is where he can maintain traction. Smooth power and torque curve. You should know that... You have a 12 port setup... It's not violent power, just usable power. The tires I've seen used, sticky track tires, will allow wheelies in the rain... From there its rider control. Sent from my Nexus 10 using Tapatalk HD Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 22, 2013 Report Share Posted January 22, 2013 Yep, total package Quote Link to comment Share on other sites More sharing options...
Paulie B Posted January 22, 2013 Report Share Posted January 22, 2013 Forgive me but what kind of tranny are you guys talking about? Quote Link to comment Share on other sites More sharing options...
KozyHeat Posted January 23, 2013 Report Share Posted January 23, 2013 I'm more worried about the chassis versus more modern bikes - Which is why I am asking about the chassis. I honestly don't know but hows the suspension, handling, and braking of an old RD is compared to modern bikes. I think that will slow you down unless you address those with some chassis mods and new components. Its not that hard to modify new forks, just make sure they got a nice set of brakes that can take racing Quote Link to comment Share on other sites More sharing options...
PassionRE Posted January 23, 2013 Report Share Posted January 23, 2013 Not being a smartass, but if you want a 554cc or larger banshee engine, your gonna need a lot of $$$$'s. Good luck with your project The main criteria I was looking at when I voiced my proposal was 20 minute solid run times on the throttle. Yes, HP goals could be met on smaller displacement engines, but with power curve requirements, smaller engine sizes would require higher piston speeds(sustained) in order to produce the power delivery styles and top-end speeds needed to be competitive. By over-shooting required displacement slightly, this would allow for HP goals to be met with safe port area margins, lower piston speeds, and increased reliability. Not to mention faster release rates of heat due to larger ex. flanges and lower velocity feeding the expansion chamber. In this manner we can build the power we need, keep piston speeds down ,and outrun the competition with gear ratio instead of rpm....Jim 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.