Today something interesting happened - with the help of my partner holding all the controlls and me with the air filter, tank, carbs held open, throttle Wide open, and aerostart straight into the cylinder my bikke fired ! both cylinders for about 10 rotations before dying off, and the action was repeatable ! however it wouldnt sustain firing this sounds like a carby problem however I have stripped the damn things 3 times and inspected all the components, at a loss here to find out what the problem is

Sounds like its not getting fuel from the carbs. did you rebuild them or just clean them?

moar pikters plz! 

Quote from: J_Walker on May 20, 2017, 10:17:05 PM
Sounds like its not getting fuel from the carbs. did you rebuild them or just clean them?

Cleaned, haven't had to rebuild them, it was just off that they worked, now they don't :/ .. the bowls are getting fuel as I have had it out and empty but after running starter over or putting petcock on prime it is getting fuel

Try holding your hand over the carb mouths (just like an old-fashioned choke) while you push the starter button. If there is no gas on your hand, you have a fuel problem. If it cranks, you know you have an excessive lean condition. If there is no vacuum, you have valve problems of one kind or another. Warning--wash your hands immediately. Also, have a fire extinguisher close by.

1. is the choke on when you are trying to start?
2. when you cleaned the carbs did you a) replace or clean the pilot jets and b) run a wire through the pilot orifice (teeny passageway beneath the pilot jet)?
3. is the idle stop adjustment completely closed? try increasing the idle stop (it could be not getting AIR to start). If it starts and runs with the idle stop set too open then you may need to clean the pilot air orifice (little hole in the throat of the carb near the edge).

Old 0.013" guitar strings (common "B" string on electric guitars) work wonders for cleaning these little channels in the carbs.

With choke on the bike should start even with the pilot fully clogged, bike would die off choke. I'd evaluate the choke (fast start jet) to make sure it's working correctly.

Quote from: mr72 on May 25, 2017, 06:50:11 AM
1. is the choke on when you are trying to start?
2. when you cleaned the carbs did you a) replace or clean the pilot jets and b) run a wire through the pilot orifice (teeny passageway beneath the pilot jet)?
3. is the idle stop adjustment completely closed? try increasing the idle stop (it could be not getting AIR to start). If it starts and runs with the idle stop set too open then you may need to clean the pilot air orifice (little hole in the throat of the carb near the edge).

Old 0.013" guitar strings (common "B" string on electric guitars) work wonders for cleaning these little channels in the carbs.

With choke on the bike should start even with the pilot fully clogged, bike would die off choke. I'd evaluate the choke (fast start jet) to make sure it's working correctly.

Thanks man, yeah I rrun it choke on and with the thorrtle just alittle cracked trying get it to fire but no dice! ill have a look at the pilot air orifiice !

Quote from: ajensen on May 24, 2017, 05:08:44 PM
Try holding your hand over the carb mouths (just like an old-fashioned choke) while you push the starter button. If there is no gas on your hand, you have a fuel problem. If it cranks, you know you have an excessive lean condition. If there is no vacuum, you have valve problems of one kind or another. Warning--wash your hands immediately. Also, have a fire extinguisher close by.

What would be the best way to check the vacuum coming into the carbys ?

Quote from: Biga800 on May 27, 2017, 06:29:29 PM

Thanks man, yeah I rrun it choke on and with the thorrtle just alittle cracked trying get it to fire but no dice! ill have a look at the pilot air orifiice !

You don't need throttle to start (and it doesn't help, unless you want to help get the carbs adjusted wrong).

JUST CHOKE and don't touch the throttle, try to start.

If you open the throttle (even a little) when trying to start on choke you may very well flood it.

Quote from: Biga800 on May 27, 2017, 06:29:29 PM

What would be the best way to check the vacuum coming into the carbys ?

Easiest way I know is to spray around the vacuum hoses with carb cleaner while it's running and if the RPM's race, you have a vacuum leak.

Quote from: Suzi Q on June 02, 2017, 07:23:16 PM
Easiest way I know is to spray around the vacuum hoses with carb cleaner while it's running and if the RPM's race, you have a vacuum leak.

Carb cleaner is likely to damage rubber parts (o-rings, diaphragm, lines, etc). Better to spray the carbs/lines with water instead. Only difference is you are looking for a drop in RPMs rather than an increase.

Like the suggestions, however I can't get it to run at all.. it turns over but does not fire and hold.. only when fully dissembled and spraying aerostart into the cylinder does it fire,

Holding the throttle slightly cracked as the RPM idle screw is fully wound out and can't set idle due to engine unable to fire.. so yeah - still no luck, tempted buy a second hand working set of carbys and see if the issue just goes..

Quote from: Biga800 on June 23, 2017, 09:48:29 PM
Like the suggestions, however I can't get it to run at all.. it turns over but does not fire and hold.. only when fully dissembled and spraying aerostart into the cylinder does it fire,

Holding the throttle slightly cracked as the RPM idle screw is fully wound out and can't set idle due to engine unable to fire.. so yeah - still no luck, tempted buy a second hand working set of carbys and see if the issue just goes..

If the engine runs on starting fluid, then you know the problem is most likely fuel delivery related. I would check all your fuel lines, then the petcock, then check for vacuum leaks.

Quote from: qcbaker on June 27, 2017, 10:53:22 AM
If the engine runs on starting fluid, then you know the problem is most likely fuel delivery related. I would check all your fuel lines, then the petcock, then check for vacuum leaks.

Yeah, trying to deduce from there though hasnt been so kind, I have drained the bowls and turned it over for a bit then noticed the bowls had filled up again, so fuel lines to the bowls must still be working alright, which leaves vacuum lines and leaks.. whats the best way of checking for them ?