where's the gas?

[centeno711]

just rejetted my carbs,(dj kit) had a problem with petcock before but it seems to be exacerbated with the rejetting.

THe bike is running out of fuel, it appears to be the vaccum petcock that is the culprit. if i pull the vaccum hose off the carb and create the vaccum myself its fine.

is there a way to make a vaccum petcock into a gravity petcock?

if not any guesses as to why i dont have good vaccum? i found that the carb boot on #2 was loose but i tightenend it and still ahve the same problem.

any ideas are appreciated. waiting for it to cool off to finish so it would be nice to have some ammo to go back with

 

[Mr Toga]

Does you petcock have a prime setting? Setting it to prime will bypass the vacuum system.

 

[TheCafeKid]

And like a gravity fed petcock leaving it in the prime position will put undue pressure on the float valves which will not be able to stave it off for long and you'll end up with gas in your crankcase. That, if you dint know, is bad. Spend the $60 and buy the correct OEM petcock and quit worrying about it for another 20 years. Fix it right
or pay for it in spades later.

 

[tlepac]

I second that!! I fussed with mine until I put up the money for the new vacuum actuated petcock! Why didn't I earlier? It was well worth the peace of mind. But if you want to try converting your petcock to gravity flow there is a thread on doing that. It isn't too hard to do but remember ALL of the petcock is old!!

Good Luck

 

[koolaid_kid]

The first thing I would do is put a vacuum gauge on the carb nipple and make sure it is pulling vacuum. If it is not, you have a different issue on your hands.

 

[tkent02]

Could be the carbs out of synch, if that cylinder doesn't have much vacuum it might no pull the valve open all the way.

 

[centeno711]

Ican feel the vaccum when i put my finger over the hose but it pulses....not sure if this is normal. so i found the posts about converting it and did that but will be buying a new petcock since that one was in poor condition.
However, should the vaccum be pulsing? with the engine at wot it was starving for fuel due to poor fuel flow through petcock. this bike has been a blast to work on and with exhaust and tires im ready to roll so this petcock deal is gonna be a real let down if it continues to hold things up

 

[Dave8338]

YES, you will feel the pulse as the #2 cylinder only draw vacuum on the intake stroke and there is no vacuum reserve to level out out the pulse strokes.

 

[centeno711]

OK that makes complete sense. THe petcock i have was messed with when i bought it. the wound copper spring under the barrel selector showed signs that it had been rebent for some strange reason and it was impossible to turn the knob without pliers. I say impossible beacuse i ahve a grip like a vise and i couldnt hold tight enough to turn it...maybe someone else could but it seems to me it should be fairly easy to turn.....long and the short of it is i modded it to be gravity fed unitl another one shows up that I am about to order. hate to spend the money but i really dont want to mess with the issues that can arise from a bad petcock. I plan on ridding this bike for a long time so....

My buddy is officialy the crash test dummy on the bike and he was blown away by the power it has. he said, "this thing is nuts it doesnt know if it want to wheelie or burn out so it just does both" you can imagine that put a grin on my face.

so thats that for now. thanks for the info on the petcock vaccum.