Carburetor question. Bowls not filling back up under hard acceleration

[silas]

This sounds like a carb vent issue. Try putting those vents & pods back to stock, incl. the little vent things on the vent lines before the pods.
I had similar problems w/ my 98 M900 after the epa stuff & carb vent pods were removed, leaving carb vent hoses hanging straight down. Stalling out can be common at higher speeds on these carbs if the epa vents & pods are removed. They have to be terninated in TOTALLY still air or the fuel flow will be blocked as described above. This happened to mine only above 70 mph and with a headwind. It would go away and run fine again if I slowed to 60 mph for a few mins. Would restart upon higher resuming speeds or a big headwind. Suprisingly, those little white vents on the carb diaphragm vent hoses don't work at all. Any air up these tubes caused me problems, even w/ the vent thingys on.   I got sick of that & went to FCR carbs.

Does anyone have a diagram of how the carb vent hoses are supposed to be routed with regards to the grey frame mounted pods? The carb vent hoses seem to each have a one way valve inline on them. Are these necessary?

[ducriderinct]

Ok. I agree, my other m900 has fcrs and they're WONDERFUL im really trying to resolve this so I can sell it

I'd love to put them back in and plumb everything correctly. Do you have any idea what the correct plumbing for the carb vent lines looks like? Do both carbs  vent hoses go to the same pod? Or one to each?

[silas]

I do not, the epa pods were gone when I bought my bike. Check the factory manual if possible. (search here for a link)
Prev. owner left the vent hoses hanging. Started causing me issues 2 yrs later for some reason. I never got rid of the issue until I got fcrs.

I'm no mechanic but I'd try long hoses run all the way to the back of the bike w/o using the pods, see if that gives still enough air. If so, remove the ugly pods.   

[ducpainter]

Long hoses aren't necessary. I ran my 900 like that for years, I had the hoses tucked up by the battery.

[Howie]

Long hoses aren't necessary. I ran my 900 like that for years, I had the hoses tucked up by the battery.

As most of us did.  Like I said, out of turbulent air.   Anyway, the two large hoses with the spring and filter go to the right pod, the small hose to the left.
                                                                                                                   

[bdfinally]

I've got mine tucked inside of the battery straps behind the battery.

[ducriderinct]

Well seafoam definitely made a difference in the ease of starting the bike. It caught almost immediately, when i tried to start it with only a single backfire before it was running.

Previously, it would be cranking for quite a bit before multiple backfires and then actually catching. 

It also felt like it ran for longer at full throttle before sputtering and losing power...

Maybe I just need to run more seafoamed fuel through the system.

[ducriderinct]

So, a quick update, after taking it for a couple more quick rides, it's starting immediately now with no fuss and no backfires.  While riding, light throttle application seems perfectly normal, part throttle use is still bogging and sputtering. Seafoam seems to have made quite a difference...

The difference I'm noticing now, however is when I push through the bogging and whack the throttle wide open, The blogging and sputtering continues for a second or so, then stops and the bike takes off takes off like it should.

It seems that I definitely have some clogging somewhere in the carbs, in whatever Circuit controls part throttle application. Where would I want to start looking for this? I'd really rather not take the whole carburetor set up out of the bike if it can be avoided. Is it possible that I can drop the bowls and remove the Jets that are affected to alleviate the issue?

Or am I back to having to pull the carbs apart and thoroughly clean them?

[Howie]

I would pull the carbs.  While there replace the needle jets and needles if they show any signs of wear.  Better idea, tell us what sizes all the jets are  buying anything.

[koko64]

There's no getting away from it really as Howie said. Carbs need periodic maintenance. You could keep running Seafoam or some other brand carb cleaner additive for a few tanks and hope for gradual improvement, but there is every chance you will be pulling the carbs anyway. Find a trustworthy mechanic old enough to know carburettors