GS850 Loss of low end torque

[texaninseattle]

This is an '83 gs850 with stock everything including airbox and exhaust. bike has about 26,000 miles
I use this bike daily m-f for commuting.
carbs were synched about 2 months ago
bike cranks and idles fine
in the past few days it seems to have lost some low end torque.
It just seems to have lost some of its pull
still has plenty of top speed and is fine for commuting but seems like its lost some of its "snap" on take off

where should i start looking?

[tkent02]

Is it any harder to start than it was?
Have you changed anything besides the synch lately?
Does it seem to run correctly other than being down on torque?
Did one cylinder quit firing?
Are the valve clearances correct?
Have you done a compression test?
Has your fuel mileage dropped?
Have you ridden a newer bike with a bigger engine lately? (that will make your 850 feel slow.)

[texaninseattle]

Is it any harder to start than it was? still starts easy
Have you changed anything besides the synch lately? no changes
Does it seem to run correctly other than being down on torque? everything else seems fine
Did one cylinder quit firing? all 4 pipes are hot
Are the valve clearances correct? undetermined until the weekend
Have you done a compression test? not yet
Has your fuel mileage dropped? hasent been acting up long enough to notice
Have you ridden a newer bike with a bigger engine lately? (that will make your 850 feel slow.) unfortunately no

this seems like it has happened overnight

[SqDancerLynn1]

What does it do at higher RPMs ? I would think carbs, plugged jet

[texaninseattle]

higher rpms are fine and will run right up to 90 with more to go (damn commuter traffic)...its just the lower rpm grunt that seems to have dropped some

[four_shot]

maybe clutch slippage? (just a thought)

[texaninseattle]

no, this is definitely a power issue and not a clutch problem

[KEITH KRAUSE]

If there's no popping or slight back-firing or dark exhaust when blipping the throttle then it's less likely to be a fouling plug but always check the plugs when you have an issue.
Check all four for proper coloring. Check the gap and any build up of carbon, etc. Clean them up and place in plug caps against the motor fins and slowly crank the motor and verify good bluish spark. If your plug caps require the use of the sparkplug "twist on ends" (forgot what they're called) then be sure they're all tightened firmly. Inspect inside of plug caps too. Be sure no copper parts or end wires are "greening". If you have any cracks in any plug leads then you should hear some "missing" when a crack allows arcing/grounding to the frame or part but inspect the leads if all else seems OK. Testing in a dark area can reveal arcing and/or snapping sounds. Also check battery voltage and condition. Weak/older battery/low voltage throughout the system can cause poor performance at different levels.
Fuel issues can cause a sudden loss of power too but are generally noticable but maybe not so much if still at a "minor" stage. Look for any signs of spillage from bowl overflow lines or the air box (worn float valve/sticking float, etc). Smell anything? Does it seem to require less choke than usual? Pull off the fuel line at the petcock, replace with a "test" line and verify good fuel flow on prime or on (have to crank motor to check). Got one of those dang fuel filters?
Check the air filter area too. Some models come with foam gaskets that can suddenly break from deterioration and partially block air flow.
If all above is OK then check manifold clamps for being tight enough and manifold condition. Intake leaks cause lots of problems though they too are generally very noticable (higher idle when motor is warmed up, harder starting, etc.)

[texaninseattle]

well, it looks like I have narrowed it down to leaky intake o-rings...a new set is on order and hopefully this will be all the ifx I need