[ThAzKat]

14.7 is neer sea level and anywhere else will be higher. Thus the reason my bike runs richer now than it did in Arizona. Arizona is at sea level in Phoenix or damn close and at 14.7 a pre 98 750 or mine ran 97 hp.

what kind of exaust do you have on there?? with that combo to make 97hp it seems everyone else is down in the 80's. i'm at 867ft. or thats what the airport says the elevation is here that should be lower that pheonix or close to it.

That is on a pre98, 93 to be exact, 750 and so stock the air/fuel mixture caps were still in place.

[Tokalosh]

Tokalosh - so how much did they charge for the rejetting and dyno?

It came to £140.00. I think it was reasonable considering that it was pulled apart 4 times and spent most of the day on the Dyno.

Tokalosh

[Anonymous]

EDR?

http://www.edrperformance.com/

tim

Oh, I was actually implying....Wow, you take it to EDR?

[lu6an]

Tokalosh - so how much did they charge for the rejetting and dyno?

[trinc]

EDR?

http://www.edrperformance.com/

tim

[01Katman]

14.7 is neer sea level and anywhere else will be higher. Thus the reason my bike runs richer now than it did in Arizona. Arizona is at sea level in Phoenix or damn close and at 14.7 a pre 98 750 or mine ran 97 hp.

what kind of exaust do you have on there?? with that combo to make 97hp it seems everyone else is down in the 80's. i'm at 867ft. or thats what the airport says the elevation is here that should be lower that pheonix or close to it.

[Anonymous]

EDR?

[trinc]

here's my first run w/ sniffer

Note that the dyno operator (someone I trust quite well -- a mechanical engineers by degree, and former investment analyst turned MMI mechanic) said that although 14.7 was theoretical perfect burn, DynoJet's tuning (both in their jetkits and fine-tuning on the dyno) always targets an idealized 13:1 air-fuel ratio as being optimal for power performance... I was rather amazed at that statement, thinking they would target a 13.8 to 14.2 range... but in retrospect, shooting for 13 should keep it from going too lean (i.e. - above 14.7) even in the worst scenario (high-rpm, shut-throttle decelleration) to keep the engine cooler and more ready to respond to fresh throttle inputs.

Cheers
=-= The CyberPoet

on that run i was running the clip in position 2 and a 120 main jet.
since i've raised the needle to 3rd position and went to a 118 main.

i really need to make another run one of these days ! they are really busy building race motors & the owner crashed at the track so they are super busy now

tim

[ThAzKat]

14.7 is neer sea level and anywhere else will be higher. Thus the reason my bike runs richer now than it did in Arizona. Arizona is at sea level in Phoenix or damn close and at 14.7 a pre 98 750 or mine ran 97 hp.

[The CyberPoet]

here's my first run w/ sniffer

Note that the dyno operator (someone I trust quite well -- a mechanical engineers by degree, and former investment analyst turned MMI mechanic) said that although 14.7 was theoretical perfect burn, DynoJet's tuning (both in their jetkits and fine-tuning on the dyno) always targets an idealized 13:1 air-fuel ratio as being optimal for power performance... I was rather amazed at that statement, thinking they would target a 13.8 to 14.2 range... but in retrospect, shooting for 13 should keep it from going too lean (i.e. - above 14.7) even in the worst scenario (high-rpm, shut-throttle decelleration) to keep the engine cooler and more ready to respond to fresh throttle inputs.

Cheers
=-= The CyberPoet

[trinc]

Update: I just got off the phone with Ivan, and he sez...
"that big dip [in the fuel-air ratio around the halfway mark] is a combination of a bad resonance in the exhaust and the fact that some DynoJet's Dyno's [including this model] use a load control that is artificially high". He asked if I could get it run again with the load-control off (since the drum weight alone is 800lbs), in which case he would expect the major dip half way through the RPM range to become a very small downward dimple instead.

He also again re-emphasized the idea of using a weaker spring or cutting the stock springs down -- said it would reduce that off-idle initial drop depth and increase the speed of the rebound upward as the engine starts to compensate for the throttle coming wide-open. I'm going to talk to the dyno guy later this week and see if I can get him to run it again with the load-control turned off to see what happens.

Cheers
=-= The CyberPoet

thanks for posting that CP - interesting results & shows why fine tuning is important.

i will only add that with the dynokit i used (k$n label ) it came with new springs that i thought were a bit stiffer. the instructions stated you could use them or not ( i did ). i've never been able to 'tune' out the off idle problem - it would be interesting to see a new run with a cut spring.

tim

here's my first run w/ sniffer

[The CyberPoet]

where is the pre98 750 kit?

Is there one? Did you bring him a pre-98 750?
Go the easy route: swap to the post-98 carbs :P


=-= The CyberPoet

[The CyberPoet]

Update: I just got off the phone with Ivan, and he sez...
"that big dip [in the fuel-air ratio around the halfway mark] is a combination of a bad resonance in the exhaust and the fact that some DynoJet's Dyno's [including this model] use a load control that is artificially high". He asked if I could get it run again with the load-control off (since the drum weight alone is 800lbs), in which case he would expect the major dip half way through the RPM range to become a very small downward dimple instead.

He also again re-emphasized the idea of using a weaker spring or cutting the stock springs down -- said it would reduce that off-idle initial drop depth and increase the speed of the rebound upward as the engine starts to compensate for the throttle coming wide-open. I'm going to talk to the dyno guy later this week and see if I can get him to run it again with the load-control turned off to see what happens.

Cheers
=-= The CyberPoet

[ThAzKat]

where is the pre98 750 kit?

[The CyberPoet]

Might as well post mine as well...
Results were: carb settings good, could use a 1/2 shim on each needle. Ivan also suggested cutting down the stock springs 1/3rd of the way, but I couldn't bring myself to do so...
This run is bike hot (205 degree oil temp), really hot garage (97 degrees, ramping up to 104 at times), high humidity day, chain slack as hell (intentionally for other reasons).



Note this does not display torque; this print out displays HP and Air-Fuel ratios, which is what I wanted (to see if it's going lean/rich/etc).

Cheers
=-= The CyberPoet