hey everyone i just got back from the dyno and my bike turned 12,300 rpms and was still pulling. we were looking for alot of rpms and we finally found the combonation that works.

 

And the numbers are??????? What brand dyno. I can tell from the way you posted the numbers were not what you expected. Man, 12,300 that is IMPRESSIVE.

 

it was a dyno like you had at your place. a dynojet rear tire dyno. and for everyone that think the tires slip on the dyno they do the start smoking. we made about 15 pulls on it. we ran a woods a 11 cams which is a sportsman cam(dam near stock). it made 60.5 HP at the rear tires with some smoke. when we put our other cam back in and our new jets it should make about 65 HP. the motor had 46hp at 11,000 rpms.

 

Those are good numbers!!! I have had a few pm's from people telling me you are lightning fast. Stock bore???

 

12,300 RPM from a DS650?!?!

That makes your piston speed an incredible 6672 feet per second (assuming your engine is using the stock stroke length). There's a lot of F1 teams that would like to talk to whoever built that engine.

I'm pretty sure the DS uses a wasted spark ignition which, unless compensated for (software set for 2 stroke single or twin cylinder 4 stroke) would yeild an RPM reading twice as high as it should be.

If the engine did turn 11,000+ RPM and was heavily modified, it should be outputting MUCH more than 46HP @ 11,000 - the stock engine is only a few HP shy of that at 6500 - HP increases with RPM for a given amount of torque.

A near stock profile cam also won't breathe well enough to develop any power at 12,000 RPM regardless of the mechanical limitations of the reciprocating assy.

Personally, if I heard a Raptor or DS650 turning more than 9000 RPM, I'd be running for cover unless it had been built with a lot of cutting edge technology and materials.

If these numbers are correct, I'd sure would like to hear the modifications it took to keep the engine from spontaneously self disassembling - c/s mods, rod, type of piston, type of valvetrain, engine case mods, etc. There's a lot of forces to be dealt with at 6500+ fps of piston speed (that means the piston is traveling well over 1 mile of distance every second - or accelerating to over 24,000 MPH, then stopping changing directions and accelerating to over 24,000 MPH 410 times every second).

I'm not trying to be critical, but 12,300 RPM doesn't sound feasible for a non destroked DS engine.

 

yes i'm still stock bore. the numbers will be higher at atoka next month and will the bike. we had problems with it there last month. i hope you can make it.

 

1986atc250r,

i won't tell what all is in the motor. i will have the dyno sheets on the computer tonight(hopfully) and i will send you a copy of it. it was set up right. we have had the DS on the dyno alot. i have the number of the place that dynoed it if you want to call them. its sandtrax in tulsa ok. he was more stuned than you. we only pulled the motor that high once, all the others was just to 11,000-11,500. i will let you know that we have been playing with our cam timing. we have them degreed in different. from what i've gathered up a stock stroke motor turning 12,300rpms the piston travels 6,663 FEET/MINUTE.

what are the practical limits for piston speeds? It depends. According to the book titled Auto Math Handbook, by John Lawlor, for stock parts, a maximum of 3,500 feet per minute or less is about right. If you use a forged crank with heavy duty rods and bearing caps you can probably get away with 3,800-4,000 feet per minute.

Notice that a shorter stroke can safely rev much higher because of the lower piston speed at a given rpm

and the 4,000 feet per minute is for a V-8 so a single cyclinder motor would be higher than that.

 

has anyone got any better numbers from there DS or raptors on the dyno? is so i would like to know what set up they were running and would like to compare dyno sheets with them.

 

Did the cams cause much low end loss? What RPM did you peak at? I dont remember if your running alky or pump gas. Did you get a torque curve as well?

 

Hey 1986 ill have you hiding under the bleachers at canyon when i pull up to the lights i hit my frist light then my throttle gose wide open i pull my second light and let her go no problem my ds loves it.and she will pull 10,000 rpm with no problem im not sure i could hit 12,000 but i don't run a tach so who knows.but i hit 10,000 on the dyno routinely.well any ways dsmike those are good no's and yes from what i have heard of you those no's sound rigth.