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650 GT airbox fun

smackeyacky

Tuned and Synch'ed
GT Contributor
Joined
May 29, 2024
Messages
40
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Location
Armidale, New South Wales,Australia
Poor little Guzzi. Went on a local group ride last weekend, the bike has been running OK but I could feel something off. It struggled on hills it didn’t used to. My mate tells me it smells rich.

Ok I figure the floats might be off or something like that. Pull the carbs, floats a bit off so I tweaked them and put it back together.

Seemingly a great result. Bike pulls like a train. Does sound a bit weird but I put that down to my awesome float fixing. I decide to give it a birthday and change the oil and stick a couple of plugs in it.

Hmm I notice I haven’t put the RHS airbox on properly and it’s leaking air.

Fix that. Bike runs like rubbish again. I look here and elsewhere for how to remove the air filter because it’s the obvious weak link here. Come across advice to unbolt the frame WHAT????

So no, you don’t have to unbolt the frame. Loosen the horns and turn them out of the way. Unhook the breathers from the heads. Unhook the oil drain to the sump from the catch tank. Pull the cover forward with the filter snug inside. Bank it over the crankcase and it comes out sideways at the front. Thank goodness for that.

But the filter. Wow. Never seen one this bad on anything including junkyard cars and farm equipment. Yuck! Explains the rich running and massive flat spot when accelerating I would wager.


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Not sure but most likely the same airbox as the Lario has. My cure was to cut out front section of airbox top, fit small piano hinge and re-install. Can now access filter in less than 10 minutes by shifting horn remove filter box closure spring, slide filter out . Replace in reverse order. The cuts don't affect airbox operation as they are on the outside of the filter.
 
But the filter. Wow. Never seen one this bad on anything including junkyard cars and farm equipment. Yuck! Explains the rich running and massive flat spot when accelerating I would wager.
Oy. That looks like most that come into my shop, where the owner says "I recently had a service done, but it still runs poorly." On those where I insist we check everything before we can do anything, almost all service items are typically WAY out of spec and condition like your filter. People want me to use a free magic wand, I wish I had. ;)
 
Finally got new filter from the UK along with some new fuel petcocks that have filters on them. I used a Honda mower filter while I waited, right width but not quite long enough so stuffed some foam in the gap. This is definitely better.

If you have an old V65 definitely check your fuel filters are still present!

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