Carbs help - gasps

[rcbedin]

Greetings!
                           
I'm trying to solve this problem with my bike (500E 2008 ) and I coun't find a solution.
When I drive around the city, usually at 50-90 km/h, the bike rides normally. It revs as usual and without any issues.
The problem starts when I get to highways. Going at 110- 150 km/h, it gasps like hell when using partial throttle (under 1/2).
If I go WOT (or at least over 1/2 throttle), all those gasps disappear and it goes up to 185km as usual.
Here's what i've tryed:
    Disassembled the carbs and cleaned them with carb cleaner (removed all rubber parts)
    Changed the spark plugs
    Inspected all vacuum hoses leading to the carbs
    Checked the Diaphragms for vacuum leaks
    Adjusted both floats to standard values (12mmm)
                           
The problem starts when cruising at 5th or 6th gear, from 4k RPM up.
                           
Would anyone have any leads?
                           
Thanks

[HPP8140]

stock air filter?

[rcbedin]

K&N dropin and sports exhaust.

But I've been running with this setup for the past 6 months without any issues...

[Big Rich]

If it only does it at higher speeds, than it is probably air flowing over / past something, causing a stumble. Look at the breather tubes on the carbs.

Just curious.... check that your gas tank vent is clear as well. I suspect it might be a fuel starvation issue....

[rcbedin]

If it only does it at higher speeds, than it is probably air flowing over / past something, causing a stumble. Look at the breather tubes on the carbs.

Just curious.... check that your gas tank vent is clear as well. I suspect it might be a fuel starvation issue....

Thanks!
I'll double check those vents. Next thing, will try to ride with the gas tank cover open for a couple KMs, see if there's any difference.

[rcbedin]

Leaving an answer to this topic...

Yeah, definetly fuel starvation at the floats.

I've stripped down the carbs and cleansed them (again). Then I've found something interesting about the needles: wasn't opening the fuel passage when sightly moving the floats down, only when hiting the bottom of the bowl.

Knowing that, I assumed it was something wrong with the float level adjuster (that small piece of metal). Float height was at def 11mm when checked.

Reducing the space between the needle holder metal clip and the float adjuster and bending up the adjuster a little bit in the middle gave me a better result when sightly moving it to open condition.

Made it and tested with compressed air coming from the fuel hose. Worked like a charm.

Came to work this afternoon with no issues at all, revving normally and keeping cruising speed as used to.

Last time a had something like this going on (my older bike), It was the bent cylinder head sucking air to the combustion chamber... That's what was worrying me...

Anyway, thanks for the advice


Enviado de meu XT1097 usando Tapatalk