vaccumn problems

[bout_it_4real]

I have a 01 b12 problem is the bike is only running on 3 cylinders and that the #4 cylinder. Hreally good spark juast as well as all the others,done a compression test on all 4 cylinders with engine cold and with it warm compression test showed on my #4 cylinder 150, #2 165, #3 150 and #1 165 which i believe to be good, visually inspected carb while bike was runnint to see if it was putting gas out and it was problem is my plug never is wet while its ere is a list of things ive already done to try and correct the problem. Cleaned the carbs at least five time thourghly, checked for vaccumn leaks,changed the plugs,swaped out the boots with the ones that arent givin a problem and yes #4 coil is producing running. Im curious and would like to know how is it that my compression in the engine checks out fine on all cylinders but my #4 cylinder isnt working and if i place my hand over the #4 carb at the mouth of it it has little to no suction unless u keep your hand over it long enough while the others will try and suck ur hand up right away?????????????

[Red01]

You must have a vacuum leak either in the carb, manifold or (though I've never heard of it), the intake tract in the head.

[bout_it_4real]

How can i test all of these places you mentioned for vacummn leaks? How do i get to th eintake track?

[Dink_1170]

You can use almost anything; Aerostart, water,WD40, and spray at the suspected area, you have found the leak when it effects the engine note, revs will rise or fall dependant upon what you use to trace the leak.

Dink

[bout_it_4real]

Hey thax im not sure as to what i have done but. Isprayed ether in the carbs while bike was running at idle #1 carb idle drop down then went back normal 1200 rpm, #3 had no change what so ever, #2 idle drop down then went back to normal 1200rpm and #4 carb idle really high until i guess all the ether has pass thru the system so what is the problem with #4 is that signs of a vacumm leak because i sprayed it in the mouth of carb intake hope this helps i dont know what else to do.

[Red01]

Try spaying the ether at suspected areas where vacuum leaks will occur, like vacuum hoses, carb tops & bodies, manifolds between carbs and head, including the mounting points.  You can't really test for a cracked intake tract unless it's right near the manifold mount as most if it is internal to the head or under the valve cover, and running one of these without the valve cover will make a terrible mess and run you out of oil in short order.

Your test seems to confirm the #4 isn't getting enough fuel... but you knew that already.

[bout_it_4real]

Hey thx ill check all this out so i guess in other words what ur saying is i do have a vacumm leak somewhere as well as it not getting enough gas or any gas to #4 spark plug?

[Dink_1170]

Hey thx ill check all this out so i guess in other words what ur saying is i do have a vacumm leak somewhere as well as it not getting enough gas or any gas to #4 spark plug?

What your results indicate is that #4 is drawing in airf in front of the carb, hence not drawing the air through the carb body and over the jet; this of course means the mixture is lean causing your issues.

Dink

[bout_it_4real]

SOOOO i guess this means i need to spray look for my vacumm leak to be somewhere areound the part where the carb connects with the manifold correct?

[mjj]

If you cannot manage a simple task of finding an air/vacuum leak, how do you know its not your carbs that are at fault?
Has it been standing a long time? Spraying water on the downpipes just after starting will tell you which cylinder is not firing.
Are you sure there is fuel getting into the carb(4)?
Is the diaphram ok, no holes splits? Float/needle valve hieght set properly, and working? Pilot jet and airways clear?

[bout_it_4real]

OKKKK update on my bike it was no a vacumm leak. Ive done a lil tinkering around with the carbs and adjustment screws and got my #4 cylinder to finally work but now the down side of it now my #2 isnt working so ive come to the conclusion that the carbs only need to be syncronized and adjusted after that i should be on the road i made a homemade manometer but my vac ports keep trying to suck the fluid down into the engine so i may have to get off the money and get them done by a pro.