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plexiform

Weird puff of air?

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Wondering if anyone has encountered this before.  I did a search for puff of air and did not find anything matching the issue I encountered yesterday and today.  Commuting to work on the highway at 70-80mph the bike was running smooth but as I got off the exit and slowed down to a stop at a light I felt  sudden puff of air on my left leg right at the level of this picture.  It was just one puff today and one puff yesterday.  No smoke, cannot tell if their was a sound associated with it.  Wondering if the cracks in these rubber parts are creating a leak?  Any advice would be appreciated.  Thanks.

 

 

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Closer up...

 

 

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Cracks in those boots are fairly common. Most of the time the cracks are on the surface and don't go all the way through. If you do have cracks that go all the way through you would want to replace the boots. Short term you could try silicone sealer or a section of rubber hose the right size. But long term replace the boots.

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Sounds like a cough. At low rpms? 3k?  Both mine do it. Throttle bodies probably need synching . A custom map helps. Just order a new set of new rubbers from MG Cycles too. That rubber is probably as old as the bike and in Cali???  Certainly dried and cracked. 

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Agreed that cracks don't usually go through, but that looks separated. While it's idling, spray some carb cleaner or other solvent on the boot. If the idle changes the split goes through.

A good tune-up and synch is always excellent method, but even if it coughs, it shouldn't cough on your leg. :huh:

(Might also check that the vacuum tap plug is not loose.)

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45 minutes ago, docc said:

Agreed that cracks don't usually go through, but that looks separated. While it's idling, spray some carb cleaner or other solvent on the boot. If the idle changes the split goes through.

A good tune-up and synch is always excellent method, but even if it coughs, it shouldn't cough on your leg. :huh:

(Might also check that the vacuum tap plug is not loose.)

Thank you. Yes this is definitely coughing on my leg.  Where is the vacuum tap plug? 

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I'll bet those intake rubbers are cracked all the way through causing a lean condition at low speed and the accompanying lean spit.

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21 minutes ago, plexiform said:

Thank you. Yes this is definitely coughing on my leg.  Where is the vacuum tap plug? 

Look at your first image. There are fasteners aft-to-fore holding the intake tract.  On the outboard side near the head, facing outward, is a hex that plugs the vacuum tap. It (and the right) should be tight, but do not over-tighten!

Looks like the Sacred Yellow Glob is still on your white synchronization knob, so must agree with Rox Lemans: time for synchronization. :luigi:

 

"Decent Tune-up" may be a good starting point . . .

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9 hours ago, Bastiaan Sponton said:

First change the rubbers. Then the tuneup. Those rubbers are cracked.

Agreed, that rubber is toast man.  Usually there’s a problem that’s not visible, but that one...

This is a good time to take it all apart and clean the tb’s- the bleed screws and plates benefit from a clean, and you’ll likely recover that creamy smooth V11 surge, yeah baby!

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