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Discussion Starter #1
HELP
I have a 1999 750 SRAD 22k on the clock, been off the road for winter since November 2019. Checked over winter and completed some works and cleaning. Started it 2 days ago and it sounds like it is running on 3 cylinders and will not idle, smells of fuel and black smoke from the exhaust. New oil and filter, new spark plugs, fuel strainer good, air filter good. I have had the bike 17 years and it always starts after the winter break. Any advice would be welcome.
 

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Would start with confirming if it is really only running on 3 cylinders or not. If it’s not firing on 1 cylinder, that will narrow down what to look at.
 

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I just touch the exhuast, 1 2 3 4 from left to right, setting on the bike, if it is cold, it is not running on that one.
I would do it when you first start the bike so the pipes are cold and they don't have to get so hot and you don't burn the skin off the end of your finger.
Have a good one ???
 

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Accurate Butt Dyno
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Narrow it down to what cylinder it isn’t firing on. My bet is clogged injector, I’d take them all out and clean them, after this many years and sitting periodically they could probably use it.
 

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I have the throttle body on the bench so will clean the injectors and re-assemble and check.
 

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So, Injectors cleaned and they were dirty, still no running right. Number 4 cylinder not running exhaust cold, swapped coils no change, swapped spark plugs with number 3, number 4 now working. Looks like a faulty new spark plug so will need to get e new one and try again. I did test the plugs for spark and all looked okay but number 4 must have a weak spark. I will let you know how i get on.
 

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Accurate Butt Dyno
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Isn’t that frustrating, you try to eliminate variables and a new part you buy is faulty. Happened to me one time replacing the slave cylinder on my BMW M6, replaces it still nothing, thought maybe master was toast, but decided to bench test the slave, turns out BMW sent me a faulty unit, I wasn’t impressed, not allot of room working on an M6, and I’ve got big XXL mitts.
 

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Update - Replaced the spark plug, still the same however all four down pipes are hot. Still sound like running on 3, very rich, lots of smoke from the exhaust. Could this be not enough or too much air getting in? HELP
 

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Discussion Starter #14
I have had the plugs out again and they a black and sooty all look the same, done as you suggested with no difference, gas is new, I have even used insulation tape around each coil just in case they may be arcing against the head, still the same.
Recap - fuel okay, injectors okay, air filter clean, new oil and filter, water okay.

Am i right in saying that if there is an air leak that this could fool the bike into thinking that it needs more fuel?
 

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Accurate Butt Dyno
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Man that’s a tough one, if you have starter fluid, do the spray test to check for air leaks, while running spray in areas you think are a problem and see if idle increases.

I’d also disconnect the battery for 10min in an effort to reset Ecu.

chasing this shit can be a frustrating thing
 

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Discussion Starter #17
I thought i would check the inlet air pressure sensor, so it should have between 4.5 to 5.5 volts going to the sensor, i am not showing that, so i will check the wiring diagram and see what i can find,
 

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Discussion Starter #18
Okay, the fast idle (choke) makes no difference on cold start up or when warm, just a thought that if this was stuck on would this have an effect on over fuelling? and if so has anyone taken this apart?
 

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its a fast idle set up, ups the idle is all, no fuel mixing

also not much to it, a cam inside the control housing, cable wraps around that, cable goes down to TB rail and there is a cam on the end of the butterfly rod and it actuates there, should have a mechanical cable/screw type idle adjuster as well the knob is right at the back side of the coolant reservoir bolt..
 
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