Replaced the fuel pressure regulator just now still showing the same symptoms. Bike will only start with the choke on, and it will rev pretty high. Turning the choke off will cause the engine to fall 1000rpm and die. Bike has had the throttle body upper and lower rubber replaced. New fuel pump and filter. New spark plugs. New Coolant Temp sensor. Injectors have been cleaned professionally. New battery. Air box door swings open and closed freely. Bike will backfire and pop when it is on with the choke.

What about valves clearance and throttle bodies synchronisation?

i haven’t checked the valves most cause i’ve never done anything like that. and i would have to take the bike to go get the throttle bodies synced and i don’t know how to do that

You must sycronise the throttle bodies. Don't just endlessly change parts. Just speeking from experience. They do go out. Sounds like you have a good machine otherwise

amart0300 wrote:i haven’t checked the valves most cause i’ve never done anything like that. and i would have to take the bike to go get the throttle bodies synced and i don’t know how to do that

The very first thing to do is to find , read, and understand the workshop manual or Clymer's.
Valve clearance is a basic control anybody can do with a simple gauge.
Idem for the throttle bodies clearance, the only thing you need is a thin screwdriver and a light to check if the flaps are closed together. Too bad you did not check it when changing the rubbers.

Have you checked the coils and leads?

Holding the green button down enrichens the mixture so you might be running lean and will have to adjust the mixture. This can be done using an exhaust gas analyser some motorcycle/ car shops might have one or if you can't access one you can use the lean drop method. Look up the lean drop method either on the forum or online. The adjustment screw requires the removal of a rubber plug on top of the RH front corner on top of the airbox. Once the rubber plug has been removed an (5mm?)Allen key can be inserted into the hole. Adjustments must be made in very small increments and after every adjustment the idle must be allowed to settle. Screwing the adjustment screw in richens the mixture screwing the screw out leans it out. If you join the local BMW motorcycle club they might have a exhaust gas analyser and someone to help.
Regards Martin.

naut023 wrote:Have you checked the coils and leads?

i haven’t

MartinW wrote:Holding the green button down enrichens the mixture so you might be running lean and will have to adjust the mixture. This can be done using an exhaust gas analyser some motorcycle/ car shops might have one or if you can't access one you can use the lean drop method. Look up the lean drop method either on the forum or online. The adjustment screw requires the removal of a rubber plug on top of the RH front corner on top of the airbox. Once the rubber plug has been removed an (5mm?)Allen key can be inserted into the hole. Adjustments must be made in very small increments and after every adjustment the idle must be allowed to settle. Screwing the adjustment screw in richens the mixture screwing the screw out leans it out. If you join the local BMW motorcycle club they might have a exhaust gas analyser and someone to
help.
Regards Martin.

I am in los angeles, i’ll try to look for a local bmw motorcycle club to help me out with adjusting the mixture

amart0300 wrote:

naut023 wrote:Have you checked the coils and leads?

i haven’t

They are pretty easy to test with a multi-meter and if you already have a multi-meter it is free 

jbt wrote:What about valves clearance and throttle bodies synchronisation?

@jbt
according to my trusted mechanic who has been servicing Ecos for decades, the valve clearance is hardly ever an issue with the venerable Flying Brick engine.
He told me that they used to check them it at Peraves CH but stopped doing so after finding again and again that the OEM valve clearances remain correct for many, many a year.
BMW have been building reliable engines for over a century.

And yes, throttle bodies sync is a different story.
amart0300, please go and check it.

@amart0300
if pressing the choke makes your bike run better, the mixture is too lean.
A very common cause is a leaky intake tract which adds more air to the previously correct mixture after the sensor has determined the right amount of gasoline injected.
Go and replace all the rubber stuff, as ageing makes it brittle and leaky.

bad boy wrote:

jbt wrote:What about valves clearance and throttle bodies synchronisation?

@jbt
according to my trusted mechanic who has been servicing Ecos for decades, the valve clearance is hardly ever an issue with the venerable Flying Brick engine.
He told me that they used to check them it at Peraves CH but stopped doing so after finding again and again that the OEM valve clearances remain correct for many, many a year.
BMW have been building reliable engines for over a century.

And yes, throttle bodies sync is a different story.
amart0300, please go and check it.

@amart0300
if pressing the choke makes your bike run better, the mixture is too lean.
A very common cause is a leaky intake tract which adds more air to the previously correct mixture after the sensor has determined the right amount of gasoline injected.
Go and replace all the rubber stuff, as ageing makes it brittle and leaky.

I replaced the upper and lower rubber on the throttle bodies and the vacuum line that runs to the FPR. Z pipe is in good condition still.

What about the small vacuum caps on tb1 -> 3 and the vacuum tube on tb4? They all split, but the small rubber caps are more prone to it thatn the vaccum tube. Also check that the tube from tb4 to the fuel pressure regulator isn't crimped if the protective spring is missing (it often is).

Moved post from general Technical, Repair & Troubleshooting, to Technical, Repair & Troubleshooting - Engine & Transmission.

Dai wrote:What about the small vacuum caps on tb1 -> 3 and the vacuum tube on tb4? They all split, but the small rubber caps are more prone to it thatn the vaccum tube. Also check that the tube from tb4 to the fuel pressure regulator isn't crimped if the protective spring is missing (it often is).

Replaced with new vacuum caps and a new vacuum tube.

Dai wrote:What about the small vacuum caps on tb1 -> 3 and the vacuum tube on tb4? They all split, but the small rubber caps are more prone to it thatn the vaccum tube. Also check that the tube from tb4 to the fuel pressure regulator isn't crimped if the protective spring is missing (it often is).

If yours is 1985 it also has a vacuum sensor...there is another vacuum pipe take off beside the fuel pipe at the front of the injector rail. This pipe is likely cracked and leaking. Just take it off and replace it with a vacuum cap.

You say the Z pipe is good BUT they can look good and be cracked too. I am in Ks long enough to find they only last about 5 years. I had to replace vacuum caps on my Sprint after only 12 months.

I have never had to adjust valve clearances.

92KK 84WW Olaf wrote:

Dai wrote:What about the small vacuum caps on tb1 -> 3 and the vacuum tube on tb4? They all split, but the small rubber caps are more prone to it thatn the vaccum tube. Also check that the tube from tb4 to the fuel pressure regulator isn't crimped if the protective spring is missing (it often is).

If yours is 1985 it also has a vacuum sensor...there is another vacuum pipe take off beside the fuel pipe at the front of the injector rail. This pipe is likely cracked and leaking. Just take it off and replace it with a vacuum cap.

You say the Z pipe is good BUT they can look good and be cracked too. I am in Ks long enough to find they only last about 5 years. I had to replace vacuum caps on my Sprint after only 12 months.

I have never had to adjust valve clearances.

I removed the vacuum tube a replaced the port on the TB with a cap, the sensor is still back there with the leads disconnected and heat shrinked. Should I reconnect the leads to it?

while leaving the vacuum line off and TB capped of course