Sucking air?

Yesterday I pulled my carbs n cleaned them and after going through all the information on this site n being real careful I put everything back but when I staqrted up there was a sound of air being sucked into the engine. Re-pulled the carbs n re-fitted stil the same - bike will only run when the choke is engaged. all boots are in good condition - where can it be oukkin in air from?
By the way 81 Maxim 650. :?

 

Check your intake manifolds. Are.they cracked? Examine them.carefully. did you replace your vacuum line back onto the.intake.boot it was attached to. Yics tube bolts back in. Did your air box boots get seated onto the carbs properly. It has to be one.of.the.things.i've listed. Focus on intake manifold boots.

Do you have brake part cleaner or carb cleaner. That's easiest way to find leak. Run engine and spray it on one specific area. If you hear the their bike rev up....you've found the leak!

 

Sorry for the.crazy punctuation. Typed.this all from a phone.

 

you forgot to mention the other 3 vacuum caps.

 

just had the same thing happen. i was suching air from the boot between the carbs and head

 

Thanx guys - I will try the spray cuz i double checked the intake boots n saw no cracks on the inside.

 

Definitely hear the engine rev a little when I sprayed carb cleaner on # 4 intake boot! I wil replace it and update. Thanks again guys.

 

Replace them all while you're at it...I learned that the hard way, replaced one, another failed months later.

It was the boot gaskets on the head side. I replaced all the second time.

They are like $11 each from Yamaha, I just got a roll of composite gasket material and cut my own, $6.

 

PS you can repair minor boot cracks with RTV sealant...not a permanent solution though...

 

Is it gaskets or an o-ring behind the manifold boots?

 

OK Don't remember any 'O' ring behind the manifold boots - PO put some kind of sealant I think.
Will pull and check

 

OK Don't remember any 'O' ring behind the manifold boots - PO put some kind of sealant I think.
Will pull and check

 

Mine had gaskets.

 

Update: Checked the manual - no 'o' rings. Went to dealer and checked - no 'o' ring.
Bought black silicone RTV gasket maker and will go the way of bigfitz and repair the intake manifolds. should I put any kind os sealent on the gasket before putting it back?

 

As long.as the gaskets didn't tear you should be alright. Try to torque the boots down according to the manual if possible. Careful not to break the bolts. And are you sure its leaking from a tear in the boots and not between the head and the gasket. Either way retighten, rtv, let set, and test. Good luck. Let us know. You got all the.manifold.boot vacuum tubes capped right. Cept for.the actual vacuum line of course.

 

Oh and before putting.boot back on. Clean the area where the gasket will go. Any bumps or dirt can hurt the seal.

 

Oh and before putting.boot back on. Clean the area where the gasket will go. Any bumps or dirt can hurt the seal.

 

Thanks Ike0, will post pics this evening.

 

Pulled the carbs - all the intake boots have cracks but only # 4 has a crack goint through to the inside. I will repair with the RTV gasket maker. I could not get my pics uploaded.

 

Success! after 4 attempts finally go it all to run. I repaired the intake boots with the silicone gasket maker then re=cleaned the carbs (clunk test included) put it all back n fired it up after about 2-3 pops while reving it settled down to a nice steady purr - still hv to take it out (raining today) :x