High RPM engine building

[Vintagewannabe]

What pipes do you have?

That will also be a factor.

Wicked motorsports

Can you get a dyno chart from them to see what the powerband looks like and at what RPM they taper off?

You would want to make sure they were capable of the revs you are going for.

I appreciate someone helping by posting the charts, and it feels like the bike is still pulling at 10k.
Just to be clear on what I am trying to do personally; The bike is at about 22k miles on as far as I know stock bore and fairly certain stock bottom end. I want to start gathering parts for a rebuild in the next year or so, and since I am rebuilding it I want to improve some. It is still very much a road bike, and while I love being aggressive on curves, I don't want to build a monster that isn't fun to ride around town anymore. RDnuTZ, thats some really good info, hadn't really even realized there were other popular aftermarket cranks.
This is exactly the info I was hoping to get together in a thread

[m in sc]

more than likely its not really pulling past 9. I have ported motors with corrected heads, etc, can rev to the moon.. and i have the rev limiters on the ignitions set to 10.2 because of over rev, to shift at 9200-9500. thats where peak power usually sits. Be skeptical on relying on stock tachs to give you correct rpm readings at speed.  they can be incorrect in either direction. my 72 r5 w rd motor was reading (jumping) too high and thats why i went with an aftermarket tach, and the 70 r5 (which is dead stock) reads too low , but thats fine on that one. a temporary digital tach on a ride will usually reveal where the motor really is. 0.02

[Yamanatic]

I agree. but they also don't see the run time a street bike sees. my r5 crank made it 27k before it started to spread to where it was an issue, but the weights were fine.  bu also a low rpm motor. imho comparing short high rpm use race bike cranks to street bike cranks are apples and oranges.

Considering that a lot of Factory R&D is gleaned from (private and works combined) race efforts, discounting comparative analysis between race and street may not be entirely accurate. Working at a race-shop/Yamaha-dealer (CycleSprings Yamaha in Tarpon Springs Florida) during the 'RD' years was most enlightening; the factory rep 'Bud Parker' had his nose in a lot of the race (and street) bike motors, and since this was the heyday of 2T competition motors CSY was a frequent stop.

I remember Daytona very well, the most motor-eatingest track there is; I raced an RD400, an SR500, and an XS11 there for several years back around 1980, and believe me, there is nothing compared to the high-rpm use any bike gets there; it's a lonnggg way around the high banking - WFO and 10K for 2.5 miles straight, then repeat again and again.

Hatched the RD400 twice and the XS11 one time at Daytona - the RD seized once, then holed a piston next time (both times on the 'banking); the seizure was bad enough that it ovaled the rod and I had to rebuild the crank - the rest was fine (10K motor with probably 1K race miles). The XS11 was a catastrophic engine failure - it broke on lap 57 in a 250-mile endurance race (the Paul Revere 250); 5th wheel gear was bushed instead of having a roller-bearing and locked tight on the shaft at 140MPH+, breaking the engine case and turning the gearbox into scrap-metal. Bud P. was most interested in that failure and since I was not the only one - a Yamaha Service Bulletin followed.

Ther main reason I posted about race cranks was to certify the reliability and strength of the stock Yamaha's. I have only lived with Hoeckle aftermarket RD/TZ cranks so cannot comment on others beyond rebuilding them, but I swear by, and not at stockers; virtually any amount can be spent building motors and that is much of the fun with the RD platform, but vast improvements to bottom-ends are expensive and not entirely necessary endeavors.

Warren

PS, my rod of choice is the Yamaha 34X - went in all the 250, 350, and 750 race motors (and a few street RDs) I've built with zero failures or issues. Racing is a true test of cranks, especially at high RPM. One possible mod to the RD might be converting to Yamaha H/D Flat-Roller drive-side main - much stronger than the ball bearing. 
OK, the pics are a TR2 race motor, but the effects are the same:
   

[m in sc]

no disrespect, but that was 45 years ago tech. metal changes with age, as does technology. there's a reason yamaha changed the design of the cranks on the the rz, lc and tzr.etc.. etc.. the vitos crank is of that same design. reality is race spec and street spec parts are different for a reason. 50 years of street use takes its toll. Aside from being pretty well versed in crank and engine building, I'm also a mechanical engineer.  we can disagree but times have changed on what's available for these street motors. while a race crank can def take a harder beating , the beating a stock crank takes overmuch more time... even at moderate rpm levels takes a toll of a different kind. its not a pissing match, just 2 different applications . but having rebuild my share of rd and triple cranks, ill never bother rebuilding a 250 or 350 crank again. ill just replace it. aftermarket can, on occasion, exceed oem quality. 2 examples of this are cdis and these cranks. Just my opinion.

[Yamanatic]

m in sc, you missed my point.

[m in sc]

quote: Ther main reason I posted about race cranks was to certify the reliability and strength of the stock Yamaha's.

that's the point I read. and I agree with tgqt.. if the crank isnt 40 yrs old. not being argumentative.