How much vacuum should be coming off Carb #2

[crackerman]

Hey now,

I just got a new petcock for my 82 GS650 and I still need to put the petcock in the prime position, mainly to start it and it runs better as well. I've run the bike in the "On" position for a while but the bike will die out on me at high speeds. I just had the bike cut out on me on the highway. Not sure what exactly is wrong but I'd figure I'd attach a gauge to the #2 carb and see how much vacuum is pulling of that.

Anyone know what a healthy carb pulls for vacuum? or should be pulling?

Thanks

[hikermikem]

leave the gas cap loose & see if it starts while in the on position... The tank vents through the cap & they get clogged sometimes.

[chef1366]

I'd check the compression.

[BassCliff]

Hi,

Are you using an inline fuel filter?


Thank you for your indulgence,

BassCliff

[Steve]

The actual amount of vacuum will vary from bike to bike, but while synchonizing carbs, I typically see about 16-18 cm of mercury on the gauge.

Pull the hose off the back of the petcock, start the engine. If you feel vacuum at the hose, you have enough.
Numbers don't really matter, it does not take much to open the petcock.

.

[crackerman]

Thanks for info. I put the vacuum gauge on tonight and it flutters around 18-24 which says its normal. This is while idling around 1300 RPMs. Still got issues when I take her out on the road.

[Spyderman]

could be the tank vent or it could be the float bowls are draining faster than there filling
it's sounding like this could be a fuel flow problem more than anything else at the moment after reading your other thread
however if you don't know the history of the bike then it would be best to do a full rebuild of the carbs and do all the orings
in the carbs and on the intake boots
others have mentioned it and it is with good reason that it has been suggested to you to do it