Rocco wrote on 04/22/10 at 23:21:52:


Rocco,
When my savage started that crap (mostly at speed in traffic)  I installed a clear in line fuel filter (always a good thing to have) that way I could see that it had no fuel in the filter and it had to be the petcock.
The savage is the only one of my 14 bikes over the last 46 years without a manual petcock, so my raptor upgrade works great for me. The savage has never ran better!
BTW... It's not been the end of the world to forget to turn it off, I have only had one flooding carb to date even on the old 4 carb honda 750. That said, you should always turn it off. It will only take one or two times of running out of gas in the first few yards to learn to turn it back on when you turn on the key.

Bigzuk

If the vacuum operated petcock, and the vacuum hose to it is in good condition, and you know for a fact that the valve is shutting down, I would have to suspect the engine manifold vacuum being lower than normal. If vacuum is not as high as it should be, I would wonder if compression is what it should be.
Is engine performance as good as it should be ?
Maybe a compression test is in order ? Low compression, or even late valve timing will definently cause low vacuum, and low vacuum will definently cause the petcock valve to shut down.

As I see it on my vac gauge, manifold vacuum on this single cylinder is not very hi anyway, (10in @ idle) and 3-5 when cruising at hi speeds, so anything less than the normal could easily cause the valve to shut down.

I had a 81 Gs550l with a vacumme valve that I was too Cheep to rebuild or replace so I got some 1/4'" hose a couple of Brass hose barbs and a 1/4" ball valve gutted the vacumme valve and put the ball valve between the Carbs and my inline fuel filter coming from the tank and plugged the vacumme port on the Carbs.
figgures out that wide open was too much gas but about half wat was great.
Miles of smiles

Hows the screen on the petcock? & the tank? Have you dumped it & flushed it? If Im having fuel issues, I want to know that the tank is clean. The inline ( clear, see thru ) filter has to be a great idea.
I think its such a good idea, everyone should be forced to do it.

wow man, you describe my petcock problem.

I have not gotten the raptor petcock yet, mean time i have been leaving it on prime, so far its been alright..

For me, one thing i notice is when shes about to cut out, pull the vacuum line cover the hole on carb and she perks right up again. during that little test i had the vacuum line open (not plugged) (while petcock in run position)

same token before she cuts out switch to prime and she perks up again..

i went to advanced and auto zone stores to barrow a compression test but they dont have any adaptors for our plug..

Blocked screens are very common.   When you take your tank off pop the petcock and blast the screen with carb cleaner.

I had such issue when I was a puppy too -- was a varnish blocked screen.

I did the petcock mod and left it in the 'on' position.  If you dismantle it you will see that it is cheaply designed, and as so many members have discovered, unreliable.  I installed a quality in line ball valve, and an automobile fuel filter.  Works like a charm.