Backfire when trying to start

[swooshdave]

I’m helping my friend, yes, I corrupted him when he rode my Greenie, start his bike. He’s been refreshing a bunch of parts.

 

Cleaned injectors. New fuel line. Manual petcock.

 

Very loud backfire when trying to start. Seems to me to be an air leak (lean pop?).

 

Thoughts?

 

 

Sent from my iPhone using Tapatalk

[gstallons]

1 check throttle body to cylinder manifold boots .

[MartyNZ]

15 minutes ago, swooshdave said:

Very loud backfire when trying to start. 

Also check valve clearances and TPS setting 

Edited August 12 by MartyNZ

[swooshdave]

Boots look real good.

Will do TPS next. I just happened to bring the pigtail with me. 

[swooshdave]

Valves have been adjusted.
Some cracks. But is that enough to not let it start?


Sent from my iPhone using Tapatalk

[swooshdave]

Sent from my iPhone using Tapatalk

[swooshdave]

The TPS screws were replaced and although he said he was super careful we are checking the TPS settings. Stay tuned. 

[gstallons]

Mmmmm. When did this happen? Now , hypnotize your friend and ask him "what ALL have you done to this before it started this problem ?
 

 

 

 

/

[swooshdave]

18 minutes ago, gstallons said:

Mmmmm. When did this happen? Now , hypnotize your friend and ask him "what ALL have you done to this before it started this problem ?
 
 
 
 
/

Right?

Tuning Guide says 157 mv. I put the meter on resistance (Ohms) and got this.

Same thing?


Sent from my iPhone using Tapatalk

Edited August 12 by swooshdave

[swooshdave]

Ok, checked the air bypass screws, set to one turn out.

Took bike back outside and tried to start it. Won’t start but the really loud backfire is gone. Now it’s a poof not a pop. Seems like we’re moving in the right direction.

Just not there all the way.


Sent from my iPhone using Tapatalk

[swooshdave]

Ok, was also told the timing sensor was removed and o-ring was replaced.

Took sensor off and measured. I got .7mm which appears to be spec.

[MartyNZ]

I think it's possible to swap the ignition coil supply leads. Could the same thing happen to the injector leads?

[swooshdave]

Just now, MartyNZ said:

I think it's possible to swap the ignition coil supply leads. Could the same thing happen to the injector leads?

You might be onto something.

[swooshdave]

You might be onto something.

We’re pulling the tank to recheck the wiring. He did mark the injector plugs (yet to be determined if it was before or after removing) so that’s something.

But I’m really curious about the ignition coils.

His goal was to tidy the wiring and it might be a little too tidy.




Sent from my iPhone using Tapatalk

[MartyNZ]

2 hours ago, swooshdave said:

Tuning Guide says 157 mv. I put the meter on resistance (Ohms) and got this.

Same thing?

https://www.v11lemans.com/forums/topic/31125-help/?do=findComment&comment=299506

I measured an old TPS removed from the TB, and got 1.22KΩ. I expect the TPS resistance to be slightly higher to get 157mv. See link above. Remember that the throttle must be closed fully, which is below idle.

Edited August 12 by MartyNZ