Breaking apart when loaded

[JEFFJ]

Hello people,
Having an issue. bike is 97, pods, stock exhaust. When i got this bike the floats were adjusted almost totally closed and the bike would only run with the choke on, removed carbs and adjusted floats, checked diaphragms, adjusted pilot screws to 2.5, reassembled and bike fired up and ran, but idled like crap, pulled carbs again and found debris in one pilot jet, cleaned carbs and reassembled, bike fires and runs good now but under load just after taking off it falls on its face and starts coughing and sputtering. checked plugs and they looked lean, so pulled the carbs again (a few times) to slowly increase the main jet size until finally ending at 108. also placed 2 washers under needles. bike definitely runs better, but still breaking apart with a load and anything over 1/4 throttle. not spitting out carbs like a lean condition, just breaking apart, thinking maybe i have an ignition problem (possibly a **** coil) or maybe the CDI box is ****. hoping someone has had this same issue and could give some advise. I have been around bikes all my life but mostly vintage stuff. So rather than throwing parts at it I thought maybe one of you could give me some direction. Thanks in advance

[DannoXYZ]

You may have vacuum-leak. Check all hoses for cracks. I remove them and pressurize them to 10-15psi and verify they hold pressure.

Also check your slide diaphragms for cracks and leaks.

Make sure your needle-jets aren't installed upside-down.

[Triple Jim]

Vacuum leaks (air leaks) are worst when vacuum is high, so if the problem gets worse as the throttle is opened, I would look for something other than a vacuum leak.

[DannoXYZ]

While vacuum levels may be higher at some operating zones, low-vacuum operation can be more affected by leaks. It depends upon the size of the crack and actual vacuum levels.

Going from 24-in.Hg down to 20-in.Hg may not impair things much. But a large rip bringing 5-in.Hg down to 0-in.Hg, will be much more catastrophic. Such as going from 1/4-throttle to 1/2-throttle at low-RPMs. This leak will pretty much disable the slides from working.

[Triple Jim]

I'm talking about leaks between the carb and head, where most would be.

[DannoXYZ]

I think I’m using wrong words. Not so much “vacuum” leaks as “hose” and “seal” leaks at the carbs themselves. I think we’re pointing to likely candidates. Not sure I’ve seen any ignition-related problems causing this issue.

[Triple Jim]

My vote is the carbs still aren't completely clean. The main jet size isn't going to help a low-mid throttle problem, since the mains control fuel at near wide open throttle.

[ducatiman]

The vac hoses *between* the carbs are frequently troublesome....borderline loose, examined cold on the bench (no doubt worse when heated in service)

Unfortunately, requires a pull to adequately examine and or replace. Splitting the carbs may be desirable to offer access... if so, have fuel and vent rail orings in hand...a most opportune time to replace them while *right* there.

Also check hose integrity at the 3 points on top of the decel valve. And for that matter...examine the decel diaphragm, seal and spring while there.

I'd suggest OP check those real careful, rule them out of the equation.