Intake Backfire

[desmodoktor]

i got this on my 02 m750. checked the valve clearances ,they are good. balanced the throttle bodies.
idk where its coming from?!?  

[junior varsity]

my fcr41's do that on the 99 m900 a bit.  lots of gas is what i thought it was from

[desmodoktor]

my fcr41's do that on the 99 m900 a bit.  lots of gas is what i thought it was from

so what was it?

[ducatiz]

preignite belch

[Speeddog]

What are the valve clearances?

[desmodoktor]

What are the valve clearances?

intake opener   0.003
intake closer    0.004

exhaust opener 0.005
exhaust closer  0.005

[Speeddog]

Those closers are loose.

I bet that with the closer clearances at 0.001 it won't be backfiring.

[booger]

Those closers are loose.

I bet that with the closer clearances at 0.001 it won't be backfiring.

+1 - I had the same problem; went away with a valve adjustment

[desmodoktor]

Those closers are loose.

I bet that with the closer clearances at 0.001 it won't be backfiring.

thank u! i ll get the micrometer today and measure the shims. then i ll order new ones! should i replace the openers as well? what do u think?

[Speeddog]

Nothing wrong with the openers where they are now, but they may tighten up a bit when you get the closers fixed.

That's not much of an issue, it's easy to make shims thinner.

[desmodoktor]

+1 - I had the same problem; went away with a valve adjustment

i hope it will go away when im done! 
did u have loss of power while riding as well? for example : doing 80mph on 5th gear and out of nowehere feeling one of the pistons not working.. and the power dropping?

[desmodoktor]

ok , so i replaced the shims.. 0mm clearance on the closers and .10mm on the openers ..
the intake backfire is still there.. i dont know what to do .. please help..
my season is ruined..   

[MaaloX]

ok , so i replaced the shims.. 0mm clearance on the closers and .10mm on the openers ..
the intake backfire is still there.. i dont know what to do .. please help..
my season is ruined..   

Any update on your situation?? I would be interested to hear the solution if any.

[desmodoktor]

Any update on your situation?? I would be interested to hear the solution if any.

sorry i didn't post anything for so long...
the solution : the intake backfire is caused from the throttle bodies.. as i said previously i adjusted the valves but it was still there...
its all on the throttle position and throttle bodies... all i did is: set up the idling at 1100-1200 rpms and balanced them with my homemade manometer.
since then the intake backfire went away.. it only happens if i downshift from 2nd to 1st and i open up the throttle REALLY fast. (i know i didnt do 100% throttle body adj)
i ve done more than 500 miles since then with no problems. no loss of power Nothing!!  last week i removed the spark plugs right after a 50mile ride to see their color .. i was surprised , they were light gray and DRY! unlike before *black and wet. thats it so far. i will have to do the vertical cylinders valve adjustment  soon because on 5-6k rpms i get this weird vibration  on the bike ...
thats it so far ..  i was scared my summer was ruined but i was mistaken.. thx to everybody here im out there riding...  thank you all 

[Lieutenant Dan]

its all on the throttle position and throttle bodies... all i did is: set up the idling at 1100-1200 rpms and balanced them with my homemade manometer.

svp88, I think I have this exact problem. Unfortunately, I don't really understand what you did in your description above. Any chance you might be able to elaborate a little? Sorry, I'm pretty new. Thanks!

Dan