The stock petcock is a vacuum operated petcock.  Prime is used to fill the carb float bowl when the bike is new, or has not been ridden for a long time and the float bowl is empty.  Use Prime if the bike has been sitting for a while.....but only to get the bike started.

In normal operation you use the normal setting - there is a vacuum diaphragm in the petcock that is operated by the smaller hose that leads to the intake throat of the carb.  When the engine is running the vacuum opens the petcock and allows fuel to flow - it does not allow fuel to flow when the engine is not running.

"FUEL" is the normal setting to use when riding.  When you are riding and run out of gas on the "FUEL" setting, you can quickly switch the petcock to reserve to use the rest of the fuel in the tank.  If you are not quick enough to make the switch and the engine stops....you should use Prime to get the engine running again.  When you fill the tank back up - remember to switch the petcock back to the the "FUEL" setting......or the next time you run out you will not have "reserve" gas to use.

FRID;

Have you looked in the Technical Section and read the threads on carbs and jetting?

If your pipes are open and unrestricted.....you might have a problem with jetting.  It is hard to jet a bike that has little (or no) restriction in the exhaust system.  Sure race bikes can do it.....but they are used at high rpm and don't need to idle or cruise well.

Generally you can get by with a #50 pilot and #150 main and 3 (or 2 in my case) washers under the needle in place of the white spacer for a stock air filer and stock or DYNA muffler.  If you start adding pod filters or more open mufflers you might have to go to a # 52.5 pilot and # 152.5 main......you can only find out by trying them as each bike runs a bit different.  I believe that a #55 pilot and # 155 main is excessive and probably too rich for any combination.  I have no idea what twin pipes will do.....it could be causing some major "reversion" problems and could make the bike run poorly.

Watch this video:

http://www.youtube.com/watch?v=KjKUKhHQLHg

Im not a Hot Rod engineer, so, I really dont know what Im talking about, BUT, I promise, Im not gonna let a little detail like That stop me.. okay?

So,, heres the deal.. The way I understand it, running an open pipe ( too little restriction) somehow messes up the torque. Now, airflow, water, whatever, you give it 2 times the number of paths to flow IN, you created a 1/2 resistance event. So, IDK what part thats playing in your problems, maybe someone else can fill in the blanks there, for me, if no one else,,

justin_o_guy2 wrote on 11/24/13 at 11:12:31:




Justin, what do we call it when the muffler clamp gets loose and lets some fresh air get sucked into the exhaust system once the pulse pases?    What are the symptoms that we have seen from that particular air leak, constantly and repeatedly over the years?

Just think of what he's done (or that he plans to do) as the world's biggest planned air leak, ever ....



Now tell him what he needs to do to fix it .....

Oldfeller--FSO wrote on 11/24/13 at 13:35:55:





On second though, Justin, it might be safer not to tell him anything, especially since he likes to go sue people at the drop of a hat.

Mebbe might be a bit safer that way .....

Frid,.. what he's saying is... unless the exhaust flow is perfectly split, exhaust air may take the path of least resistance for the most part... and this would make the other muffler suck fresh air rather than blow exhaust at certain pulse points... that would be equivalent to creating a large air leak in the exhaust (which is a major cause of backfires)...

In that case,.. you might want to block one muffler completely, making it decorative but not functional...

serowbot ,,, thanks , but oldfeller you are a piece of work , i lived beside someone like you before ,i can see you are a very smart man ,you know a lot , that's good ,but in how you say an talk to others , you come off as smartass . people ,not all but a lot ,people who have a lot of knowledge sim to a smartass when others like me may not know things about muffers , backfire ,leaks ,what ever it maybe .but one think i do know im smart in a lot of ways . i invent things an make prototype's of all i make . i spend i lot of time on the road looking for investors .people love what i have but people have no money to help to get it on the market , just not finding the people i guess .so im smart to but don't make other feel like nuts . now on that note , i thanks all who have help me . an with oldfeller being on here watching all the questions people have an being a smartass , i will find another forum to go to . thanks again for your help people