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Dreaded Vapor Lock


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97 deg F at 9000', and I had a bad case of it. I have two questions, hoping someone has trod here before. Looking at the fuel pump roosting above the LH cylinder, I realize it has to be moved. But where? By removing the air box, there is room to locate it at the rear of the spine. So, first question: Has anyone relocated the pump, and where? Second question: Has anyone run K&N or other pod type air filters, and how has it affected the bike? I have heard that air box volume is critical to the tuning of these newer bikes, and I don't want to spend the money on K&Ns to find my Guzzi doesn't run well with them. If no one has tried this, I'll try it, and post the results. This is on a 2002 LeMans.

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Older bikes (like mine, I'm not sure about the original V11 Sport) have the pump above the timing chest but you may have the oil cooler in the way. But you might want to try replacing the fuel tap solenoid against a manual tap. You never have to close it anyway unless removing the tank. This has solved the vapor lock problem for some.

 

I have never had a vapor lock problem. Manual fuel tap, pump in front and filter between spine and the RH cylinder.

 

Like most other changes to the engine, the air filter harmonics is a compromise. I could see negative effects in mid-range using pods, while there probably was a positive effect at very high rpm. That didn't suit me at all so I soon put back my air box.

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It looks like Jaap put his below the steering damper in front of the oil cooler. I think the Tenni's might have had the pump mounted there from the factory?

 

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Others here have installed firesleeve insulation over the fuel lines. Make sure your lines are well away from the heads.

 

If you remove the airbox you will probably need to adjust the fueling with a Powercommander or MyECU.

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After experiencing vapor lock almost every time I took the bike out on long rides on hot days, I decided to wrap my fuel pump with heat shield tape as a cheap, low-effort experimental fix. I didn't really expect it to work, but figured it couldn't hurt. I've ridden about a thousand miles with this solution and it has started right up every single time, even in situations where before it would have had no chance due to the heat. Such a simple fix, wish I did a long time ago! So I would suggest that this is worth a shot as a first try before doing anything more involved.

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Mine came from the factory this way. This summer the complete setup will be on the for sale list on this forum.

 

That's odd. My Lemans is the same year and even the same colors as yours was and mine has the spine mounted pump. I guess mine was built before the change?

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That's odd. My Lemans is the same year and even the same colors as yours was and mine has the spine mounted pump. I guess mine was built before the change?

I have never seen a V11LM with the same setup I have (had). Maybe mine is a Tenni incognito.

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I have never seen a V11LM with the same setup I have (had). Maybe mine is a Tenni incognito.

 

Jaap, your V11 has long been even a LeMans Incognito!

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Cheapest and easiest fix that works for many vapor lock sufferers is the reflective heat tape, or similar shielding stuff, followed closely by installing a manual petcock. Although, I did it other way round and the petcock did the trick.

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