Fuel pipe in to top of GRiSO transmission?

So I am a new (less than a year) owner of a 2005 GRiSO 1100, I had the fuel tank off in the past week to change the inner spark plugs, which was a good idea as judging by their condition it looked like they were still the original ones!

Anyway, job done, nice new shiny plugs fitted, when putting the tank back and connecting everything up I noticed that the fuel drain hoses were teed into a pipe that routes into the top of the transmission cage (photo linked below), Seems strange to me, however, on checking the parts list that pipe into the transmission is listed as a fuel hose (labeled 16 in the attached parts list diagram)

I always assumed the fuel tank drain and tank air inlet hoses that are teed together would just drain down under the bike and indeed I do see another drain hose unconnected in the same area that hangs under the bike near the rear shock. Makes mw wonder did someones else previously route these hoses incorrectly? Appreciate the wisdom/advice of the experts

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Yes, your bike has been 'Fettled' by a cretin. There are two tank drains. One is the vent and overflow, the other one is the water drain from around the filler.

In some markets the vent and overflow is fed to a charcoal canister to help prevent hydrocarbon escape into the atmosphere. In Ireland though I'd expect it to simply be vented under the bike. The water drain always just runs under the machine.

The gearbox breather also should just have a hose on it that loops up above the airbox and had an end open to atmosphere above the throttle cam on the LH throttlebody.

It would seem that some genius has thought that things could be 'Tidied up' by running the two tank hoses together and connecting them to the gearbox. The result of this will be water from the cap and excess fuel and vapours from the tank being directed into the gearbox. The gearbox will still vent as it gets hot, (And fills with fuel and water!) back up through the water drain hose from the filler cap drain but the gearbox will gradually fill up with water and the gear oil will be degraded with fuel contamination!

Fix it. Preferably years ago.......

Pete Roper wrote:

Yes, your bike has been 'Fettled' by a cretin. There are two tank drains. One is the vent and overflow, the other one is the water drain from around the filler.

In some markets the vent and overflow is fed to a charcoal canister to help prevent hydrocarbon escape into the atmosphere. In Ireland though I'd expect it to simply be vented under the bike. The water drain always just runs under the machine.

The gearbox breather also should just have a hose on it that loops up above the airbox and had an end open to atmosphere above the throttle cam on the LH throttlebody.

It would seem that some genius has thought that things could be 'Tidied up' by running the two tank hoses together and connecting them to the gearbox. The result of this will be water from the cap and excess fuel and vapours from the tank being directed into the gearbox. The gearbox will still vent as it gets hot, (And fills with fuel and water!) back up through the water drain hose from the filler cap drain but the gearbox will gradually fill up with water and the gear oil will be degraded with fuel contamination!

Fix it. Preferably years ago.......

OK, thanks Pete, that sounds obvious now when you describe it.

Luckily (?) when I had the tank off I discovered that the left side (water drain) connection was blocked completely solid with a fair backup of dirty water trapped, that is now cleared that gunk at least did not make it down the geniuses plumbing route due to the blockage.

Anyway I will sort the plumbing immediately and change the gearbox oil also to be safe, luckily I have a litre of 75W90 manual gear oil in the garage from pre lockdown, thanks again for the fast reply, appreciated,