Dyno run finds fatigued engine??

[cbartlett419]

this is what's so boggling about the whole thing, The bike runs fine, it falls off higher in the rpms but doesn't hit a wall as if something catastrophic has occurred.  Look at the power curve, nice and linear it rides like that. What bothers me is him saying he added enormous amount of fuel and the air/fuel curve still climbing out of range. Has anyone here operated a dynojet machine?

[Speeddog]

I'd say operator error or dyno malfunction.

I've ridden a Ninja 250, and IIRC my comment upon return was 'painfully slow'.
Those are ~25HP.

[hillbillypolack]

Well, for starters, you did some serious dinking with the exhaust, which is usually the source of gains but you could also go backward too if the flow isn't done correctly.  Pods, when not properly set up don't get instant gains either.  Last, while I'm not an expert on smaller Monsters' heads, you put 620s on a 750??  Is that working backwards, or is that reasonable to do?  I'm just asking.

I agree the numbers read low.  But your curves are also erratic.  The F/A should at least progressive, and yours is jumping around a lot.  That engine needs to be baselined, run on a consistent dyno with any changes you make.  A single peak number will not a great engine make.

[ducpainter]

620 heads flow better than 750 heads.

[Langanobob]

Hard to read the date and time stamps on the two dyno runs but it looks like they were on different days?  Is it possible he got some other bike's dyno runs confused with  yours?  Not likely, but something sure isn't right.

My main concern is that the lean condition that damaged your original heads may still be there.   If the dyno run printout is correct, it sure is still there.  I don't think you mentioned what the exact problem was with the original heads?

Bob

[drunkfatguy]

Something doesn't look right, what type of method did the tech use to read the A/F? was it a "Sniffer probe" or a screw in type sensor? My money is on what others have said- the dyno may be out of Cal. I'd find another shop and have it re-done just to be sure.

[Monster750ie]

A Honda rebel makes 18 HP and weighs 320 lbs top speed claimed 80 but it's really between 65-71 at least for me.

The monster easily weighs 100 more so if it was making 19 HP top speed would be 50-59 ish.

Was there any wheel slip? I would have them do back to back runs between the monster and one of their bikes.

[zooom]

  The bike runs fine, it falls off higher in the rpms but doesn't hit a wall as if something catastrophic has occurred.

BTW, exactly this is what I experienced with a 2 into 1 with my 900 track pregnant dog...so I changed out to a regular high mount exhaust once I realized I was shortchanging myself in that regard...hence why I said what I said in my 1st post on this thread...but yeah, either the machine operator is not able to do his job properly, or their machine is way out wack in terms of calibrationwhich is why I said to contact Dynojet for other authorized places...

[cbartlett419]

Good enough. Dynojet's website steers me to a shop an hour away, I'll drag it over there whenever I put the fires out in my world

BTW the valve guides went bad in the stock heads, lost power from the top down until it got to the point that at 4K rpm it was chugging out. I was making a 6 hour ride every other weekend for a couple months, it didn't take long.

Thanks for everyone's input, I'll let you know what the next guy says. 

[brad black]

there is no calibration for a dynojet in acceleration mode, it is what it is.  i don't see what being a harley shop has to do with it either.  dynojets are pretty fool proof.  don't understand the 19hp tho.  it would have to be very sick to make 19hp.  if it had that little comp i don't think it'd start.  it's not some sort of partial load run maybe to get a number like that?  never played with a dynojet 250i with a brake enough to know if you can do that.

i don't see why the mods you've made would destroy both heads either.  has it got fuel pressure, had the filter replaced recently, got dirty injectors, etc?  a good 750 should do pretty close to 200km/h (120mph) i'd think.

[cbartlett419]

*noted   you sound smarter than the average bear concerning the dynojet machine, would the air/fuel curve trouble you??     I can't remember when the fuel filter was changed, I'll put that on the list of things to do.