99 FE400, cuts out on landing a jump...

Try putting Ts on the vent lines. Run the upper hoses up high and the lower hoses the way they should be. Might help. Do a search on float adjustment. Hope this helps.

Sounds to me like the float isn't set right. Specifically, it sounds as though the float level is too low, ie not enough fuel in the carb. Check out the following page it's a good place to start.

http://www.ducatimeccanica.com/dellorto ... lorto.html

Hope this helps,

Your welcome. Your page is very similar to the page I linked. Good Luck!!

You can try enlarging the bolt at the bottom of the carb to allow more fuel to surround the main jet.

Nickelodeon,

I have problems with my engine cutting out for a fraction of a second when I am WOT through the biggest and nastiest of whoops. Seems that the little whoops are nothing, but the big ones cause my bike to coff at the bottom of each dip, much like a hard landing off a jump. My theory with the Dellorto carburetors is that a sudden impact with the ground, at a high enough speed or velocity (which I believe is relatively low in the case of the Dellorto), allows the mass of the fuel inside the main jet to overcome the vacuum pulling it out. In other words, the kinetic energy of the fuel moving from the float bowl through the main jet into the venturi of the carburetor is overcome by gravity and also the abrubt change of direction of the carburetor (ie. motorcycle) during a harsh landing wether it be a jump or a whooped out section of terrain. The float bowl of the carburetor holds sufficient fuel storage for several seconds of WOT ridding so I would presume that if fuel starvation was a problem, it would not be noticed only during jumps as the landing from a jump is only a fraction of a second to two seconds tops, not enough time to deplete much fuel from the float bowl at all.
I personally feel that this is just a design flaw and weakness of the Dellorto carb and if you want to rectify it you will be better off moving to a FCR. Of course this is only my opinion and theory after pondering this topic a few times myself. :?: That brutal rush of rear wheel spin almost comes to a complete standstill for a fraction of a second when I hit those hard whoops hauling ***..... almost throws me right over the handlebars, then the power comes right back after an instantaneous stall and my arms get ****** out of the sockets as the bike bike lunges forward moving back into warp speed. :wink: These are my thoughts on the topic, anyone else have an idea or know something we don't?

Regards,

Fuel is likely being splashed into the float bowl vent lines momentarily cutting fuel supply hence the introduction of "T" vents.

Dale

Nickelodeon said:

I guess I should have take Wild Bill's advice earlier. My two top vent hoses are shaped 180 degrees, facing downwards....I thought this was a good thing(it's the same way as I bought the bike)...

I figured water couldn't get in that way.

Now the bottom vent, that was cut short when I got the bike, and cut where it would dump fuel right on the exhaust pipe, which was of concern to me, so I replaced it and ran it to just above my swingarm pivot(maybe too low?)

Two questions:

1. Do I use a plain old brass "T" fitting, and route the two top vent hoses into it? What of the lower vent?

2. How does a "T" fitting stop the vents from getting plugged up with gas when it's sloshing around?

Thanks.

Nick

Click to expand...

You can use plastic Ts. There is a kit out that can be found in a Dennis Kirk. The kit comes with 4 Ts and a length of hose and a filter box.
What the T routing does is prevent vapor lock, if fuel splashes into the vent. That prevents air from entering, with just the downward turned hose. With the T air enters from the above as well.
Can find same size hose at Wal-mart at fish tank supplies. Take a length of old to match up.
Hope this helps