Topic: 550 with Cruzinimage 605 kit and Mrieck Head work with Dyno print out& VIDEO

[flatlander]

it's good to see this data. i'll be watching the thread with interest.

There was a guy here years back that planned an overbore on an otherwise good running stocker. He dyno'd the bike before he tore it apart and it was 36 RWHP.

i see these figures of 36 or 38 rwhp sometimes being mentioned. does anyone know if they are based on a couple of individual bikes, or an established average for stock 550s?

my own 550 in stock configuration put 44.6hp on the wheel, just after tuning carbs and ignition: http://forums.sohc4.net/index.php/topic,134863.msg1522043.html#msg1522043
ok maybe i got lucky with a good copy of the engine, and certainly not all dynos are the same but this seems to be a huge difference?

[bwaller]

Seems you have a good one.  Truth is there are not many dyno reports from stock 550's. I remembered that one fellow because his approach was thorough and he claimed his engine ran very well. This was years ago and I watched to see what happened after the rebore, but never saw anything.

[Tews19]

Maybe someone who understands this will chime in. while talking to the dyne guy he mentioned peak HP is at 5250 rpms. He said that is when the torque and hp cross one another. That is where the numbers are taken. Or i may be saying all this incorrect but that is how i am recalling it. Does that sound normal? Or this may have been for an entirely different bike.

[MCRider]

Maybe someone who understands this will chime in. while talking to the dyne guy he mentioned peak HP is at 5250 rpms. He said that is when the torque and hp cross one another. That is where the numbers are taken. Or i may be saying all this incorrect but that is how i am recalling it. Does that sound normal? Or this may have been for an entirely different bike.

PEak torque is generally around 5250. HP is wherever the engine peaks, much higher.

[MRieck]

If peak HP is at 5200 RPM there is a problem.

[Tews19]

Mreick, how can i tell where peak HP is?

[Jerry Rxman Griffin aka MuthaF'er]

Top of the dyno curve on a properly tuned engine.

[scottly]

Maybe someone who understands this will chime in. while talking to the dyne guy he mentioned peak HP is at 5250 rpms. He said that is when the torque and hp cross one another. That is where the numbers are taken. Or i may be saying all this incorrect but that is how i am recalling it. Does that sound normal? Or this may have been for an entirely different bike.

Torque and HP ALWAYS cross at 5252 RPM, regardless of where the peaks are, as 5252 is a constant in the formula for Imperial HP. (ft-lbs X RPM/ 5252) The HP peak on your best run isn't shown on your printout. For example, look at this print of a recent run on an FT500 Honda thumper: the torque peak is about 4300 RPM, and the HP peak is about 5900 RPM.

[SOHC4 Cafe Racer Fan]

I suspect that you also gained some low and mid range torque even with the normal compression overbore kit. 

I say tune it, enjoy it, and if you want a little more gusto down the road, replace the cylinders and pistons with the Wiseco kit and slap on some CR26s.   

I think that 44.6 hp at the rear wheel is quite rare for a stock 550; that Dyno might be a little bit optimistic, or that might be a very well put-together engine.