I tried not to, but I have no choice...another carb question

Where does the vacuum line from the petcock run to? I've been searching and reading and searching and reading and looking at pictures from different angles in hopes of them revealing it's location. No luck. I've been at it for a over a week now. The bike will start and run for a few seconds then fade out. I've been over the carbs several times now and I feel I'm sure about everything except the end location of the vacuum line. This is my last hope. Even though I don't want to, I've never had to before, I have always been able to figure things out on my own, this one might have to go to the mechanic though. These carbs are from hell. Any suggestions and help would be greatly appreciated.

 

It goes to the brass nipple on the #3 carb intake manifold rubber "boot", which may (should!) currently have a rubber block-off cap on it.

All of the intake manifolds have the vacuum nipple, and thus you can actually run the petcock vacuum line to any one of them, but the factory did it on the #3 intake.

 

Any one of the four Vaacuum Ports on the Intake Manifolds.
Factory set-up is Number 3

Then, there is the little Vacuum Pick-up on the Petcock.
Make sure you are running real VACUUM Line.

I had a guy use the Vinyl hose that came with his new Battery and it would get hot and collapse down on itself.
The bike would starve for fuel, but the Manifold would still be sucking on the hose.

 

OK, so I've had it hooked up to the #1 intake, I'll try moving it to the #3 and see if that makes a difference. Thanks

 

Re: I tried not to, but I have no choice...another carb ques

Couple things to try. Try running your fuel supply line into a suitable container and switching your petcock to the prime ("PRI") position if it has one. In this position fuel runs freely no matter what. Not good practice to leave it in this position for many reasons, but it serves the purpose to see if fuel is flowing from your tank. If you ARE getting fuel on prime, then switch back to ON. Remove the vaccuum line from the carbs and, with the fuel line draining into a suitable container, suck on the vaccuum line and see if fuel flows when you do. Your petcock vaccuum feature may not work.

If you do not get fuel on prime, then you've likely got sediment somewhere clogging stuff up at least partially. Maybe the filters built into the petcock or the in-line filter if you have one installed.

Good luck and tell us what you find out!

 

You may also have partially clogged "Beenie-screens" on the ends of the Float Valve body's.

Fuel will get by keeping you Idling and running slow ... But, as soon asa you get on it ... the clogged Beenies restrict the Inlet Flow so badly that the Bike runs short of Fuel v ery rapidly.

Not clogged enough to actually stop the flow, there is a short peroid of recovery and the Bike will run right, again, for a moment or two until the Bowls are drained by demand.

You might just have your Pilot Mixtures set too Rich.
That will bogg you out in a heartbeat.
The Bike runs fine and responds pretty well at Wide Open for a bit ... but, won't get out of the hole very well because the too Rich Pilot Mixture won't Ignite until the Butterfly's are opened and the Main Jet Supply feeds the Cylinders.

Then, we go back to the Beenie Screens ... The Bike wants to go ... and will for a moment until the supply in the Bowls is depleted and the Bike boggs-out for lack of Fuel Supply!

Carb work.
You have to pulll the Carbs and clean them ... blowing Carb Cleaner and compressed air through the Float bodies.

And don't forget the possibility that the Diaphragm Pistons could be sticking on you rendering the Bike slow to accelerate because the Pistons are not rising fast enough when you open the Throttles.

 

Re: I tried not to, but I have no choice...another carb ques

:twisted: :twisted: so how does a guy test for faulty diaphagms?


Sweet! I made "gear grinder" status!! woohooo!!!! :twisted:

 

Suck on the hose as described above ^^^

 

So I did the little test and found that my diaphragm in the petcock was plugged. I took apart cleaned it out and cleaned out my fuel tank again. The bike started up with a little help and continued to run on it's own! Now it seems the #1 and #3 cylinders are not firing. The pipes were cold on them while the #2 and #4 were cookin off new paint. When I checked all for spark everything was good, and when the bike was runing I grabbed the #1 plug wire while it was still hooked up and recieved a good jolt. Didn't want to try the #3. What does this mean?

 

Fuel
Air
Spark
Compression.

If you have spark all you need is a little Fuel and Compression.

Compression check. Even if its just the "Finger on the hole" method.
If you have Compression ...

The Pilot Mixtures are in question.
Pilot Fuel Jets Clogged?
Float Heights.
Pilot Fuel Passage clogged?
Pilot AIR Jet Open?
Pilot AIR Passage clogged?

Pilot Mixture Screws.
Colortune
Ball Park Pre-set to: 3 Turns Out
Tweak for best Idle.
Plugs?
New Plugs; please!