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Discussion Starter #1
Hi Guys. I spoke to my car mechanic (automotive diagnostics center) about my low rpm throttle surge again (he does not want to work on my bike because they don't do bikes and because his system does not connect with the MV Magneti Marelli ecu) he offered and took a ride on my bike as a favor. (He also probed the injectors, ignition, crank sensor, and tps with an oscilloscope and all pulses were stable and as expected, no spikes, but he could not determine the actual ignition timing/angle and if he could he doesn't know what correct valuas are) After the ride he said the bike felt like the ignition timing was way to advanced between 2000 and 3000 rpm. Maybe the engine even mildly pings in that rpm range under load. He motivated his opinion by stating that when he was riding in first gear at a few mph the sligtest throttle movement resulted in an agressive accel jerk because the blip of extra air and no load would result in an extremely early flame front to expand and succesfully push down the piston. However under load when accelerating WOT in any gear the extremely early flame front would not be able to push down the piston faster which results in holding back and rattle between 2000 and 3000 rpm. He said it is most likely and ignition problem because it also happens on a cold engine and specifically between 2000-3000 rpm. I fueled it up with 102 octane a few time to see if it reduces the problems to exclude detonation but heat and octane to not seem to impacting the jerk, holding back and rattle. Say he is correct. What could possibly impact the ignition timing? Could it be ECU hardware related? Do any sensors impact ignition timing?
 

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First, what year and model of bike?
Second, any modifications?
Third, why talk to a car mechanic with no experience nor the tooling?


I am going to say this about that: your car mechanic is dead on.

The timing is advanced to meet emissions from the factory. It has been discussed ad infinitum in many threads within this very forum.

The solution to the issue relies on tuning the ECU.

Where are you on this planet? There are people who do this work very well.
 

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One more thing...burn the fuel octane the manual calls for. Anything else will do nothing but cost you money and crud up your valve tract.
 

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?

No! Chuck, the ignition timing is retarded
a 1000S is -4° initial
a 1000R is -10° initial
don't have numbers for later bikes

these are the 2 dumbest timing numbers I know (RSVR Aprilias are close)​ .....peak cylinder pressure is way too late, part of the combustion occurs in the exhaust port and pipe.....think that's why they run so hot??

Adam, has built real ignition and fuel maps and eliminated the stupid EBS System, totally transforming the bike

My Big Block Chevy runs +15.5°, never gets hot and blows 4.5% of what it's allowed to.....and gets 22.9mpg city/highway

You have to reference MAP to write fuel and ignition maps .....MAP shows the load on the motor

If you don't know the load, how do you write the maps?????

:wink2:
 

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750 B4 : start with a tps reset, I'm assuming that plugs, air filter, fuel filter etc are all newish. And as mentioned use the correct fuel, it will run better on it once the issue is sorted.

There is a sensor near the F4 cover, check that hasn't worked loose.
 

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Discussion Starter #6
First, what year and model of bike?
Second, any modifications?
Third, why talk to a car mechanic with no experience nor the tooling?
Where are you on this planet? There are people who do this work very well.
It is a 2004 Brutale 750. It has a straight? collector pipe (no can) and a performance air filter. The ecu has also been opened so i think it has a swapped Eprom.

I went to this mechanic because he has a strong reputation on automotive troubleshooting and doesn't charge me if he can't fix it. I went to a few bike shops and they just try to sell me a major service job or hysterically start suggesting to start replacing all kind of parts or wanne charge me 150 bucks in advance without moneyback or solution guarantees.

But this bike ran good or at least better before than how it does now. How can pinging occur suddenly, what can cause that?
 

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@theknurl....dammit. I'm going to have to go check my tables again. I thought the MV, at least my 312R and my 1090RR were too advanced. If I'm wrong, I apologize.
 
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