Intermediate loss of power

[GBABOB]

Hi, My son recently bought an 81’ GS650G. We are new to Suzuki’s and motorcycles in general. I have found a wealth of knowage on this site. When we bought the bike the carbs where leaking fuel into the airbox so we pulled them off and took them to a mechanic and he cleaned and bench flowed them. We reinstalled the carbs and found it would run ok but had no power. After some investigation we discovered that the intake boots where shot. We replaced the boots and o-rings with new ones. We have also replaced the airfilter. Now it has the loss of power on a intermediate basis, sometimes it runs like a scalded ape other times it can’t get out of it’s own way. Where should we look next? Thanks

[chef1366]

Check fuel flow from the petcock. This is a part that should just be replaced to insure good fuel flow.

[GBABOB]

I think the petcock is working semi-well fuel seems to flow ok when it's in the prime position but the engine doesn't run differently with the petcock in any of it's positions. The petcock does get wet with gas when you turn the valve stem. If petcock wasn't working wouldn't you at least a small burst of power from the fuel in the float bowels before they where starved from the lack of fuel from the petcock?

[chef1366]

In my experience a bad petcock will show intermediate issues.
The problems really show up at highway speeds where there is more need of fuel.

If you are certain this is not the issue than check the vent lines off the carbs and the vent in the fuel cap.

If these aren't the issue move to ignition.

[GBABOB]

I think the petcock is working semi-well fuel seems to flow ok when it's in the prime position but the engine doesn't run differently with the petcock in any of it's positions. The petcock does get wet with gas when you turn the valve stem. If petcock wasn't working wouldn't you at least a small burst of power from the fuel in the float bowels before they where starved from the lack of fuel from the petcock?

[chef1366]

Bad petcocks do not flow fuel consistently. This would cause bursts of power and no power periods.
Bad venting will also cause poor power.
So will weak coils
Bad connections and/or low voltage at the coils and ignition
Bad battery
Bad coils at the crank trigger
Poor grounds
Low compression
Poor sealing valves
Worn out cam chain
Bad spark plugs
Dirty carbs

[seuadr]

i had to replace plugs and wires to fix a weird intermitant problem with power.. i second checking those. (and of course everything else chef says, he's a guru!)

[chef1366]

i had to replace plugs and wires to fix a weird intermitant problem with power.. i second checking those. (and of course everything else chef says, he's a guru!)

I'm no guru. I'm humbled by the guys at the Dragstrip. Check out some of Lecroy (Mark's) posts. He's a guru.
I was just trying to figure why the same post was posted twice. Didn't like what was said? I almost went somewhere I'd regret but you can't really tell peoples intentions on the net.

[GBABOB]

I just hit the button twice by accident, sorry.