footgoose Posted July 12, 2021 Share Posted July 12, 2021 Have you replaced any on yours docc? and I'm curious if the MGCycles replacement part is oem or aftermarket. Link to comment Share on other sites More sharing options...
docc Posted July 12, 2021 Share Posted July 12, 2021 17 minutes ago, footgoose said: Have you replaced any on yours docc? and I'm curious if the MGCycles replacement part is oem or aftermarket. When I was chasing oil leaks through my "bell housing", I first looked to fit the "Ford coolant hose" that is similar and can be fitted, but the valued consensus was that it would swell and fail. So, I sourced the correct Moto Guzzi vent hose / "breather pipe" 30 157 400 (from MG Cycle). I saved my original as it was not cracked and not leaking in 2014 at about 90,000 miles/ 145.000 km. (My leaks were "elsewhere") 1 Link to comment Share on other sites More sharing options...
docc Posted July 12, 2021 Share Posted July 12, 2021 Are these two current threads about the same thing? Left side airbox crankcase vent oil accumulation that drizzles out and runs down the left side of the gearbox? @Grim, what does that junction look like on your airbox connection to the throttle body? 1 Link to comment Share on other sites More sharing options...
Grim Posted July 12, 2021 Author Share Posted July 12, 2021 Yes it looked exactly the same, I added a hose clamp where the breather hose joins the airbox, as the hose is loose I didn't have a good replacement. It won't stop the oil INSIDE the airbox leaking out around the plastic intake trumpet though! 1 Link to comment Share on other sites More sharing options...
gstallons Posted July 12, 2021 Share Posted July 12, 2021 The quality of rubber used making the hose . You will notice there is not even thread woven into the hose ! You can blame MG , the vendor that makes the hose , whoever you want . It is NOT Japanese (QUALITY) rubber . 1 1 Link to comment Share on other sites More sharing options...
bbolesaz Posted July 12, 2021 Share Posted July 12, 2021 17 hours ago, gstallons said: They will fail if you keep the bike PARKED Or, if the breather return hose completely fails while on the freeway, the oil covers the back of the motor and drips onto the exhaust. The resulting cloud of smoke alerted a police officer 2 miles away. He pulled me over, but let me continue to an Auto Zone nearby. Fortunately, the oil will drip onto the side of the rear tire, but not on the tread center. 1 1 Link to comment Share on other sites More sharing options...
Lucky Phil Posted July 13, 2021 Share Posted July 13, 2021 22 hours ago, gstallons said: The quality of rubber used making the hose . You will notice there is not even thread woven into the hose ! You can blame MG , the vendor that makes the hose , whoever you want . It is NOT Japanese (QUALITY) rubber . I just used 8mm EFI hose on mine. Even plain rubber hose is fine, it carries no pressure, it's just a vent hose. Same for the big hose from the crankcase breather. They seem to last about 5 years or so before they start to perish. They are in a hot environment. Ciao Link to comment Share on other sites More sharing options...
Grim Posted July 13, 2021 Author Share Posted July 13, 2021 4 hours ago, Lucky Phil said: I just used 8mm EFI hose on mine. Even plain rubber hose is fine, it carries no pressure, it's just a vent hose. Same for the big hose from the crankcase breather. They seem to last about 5 years or so before they start to perish. They are in a hot environment. Ciao I like the shiny blue banjo... On pre-pump in tank bikes the hose has to bend round the fliter at a wired angle too, so it hits the airbox at an angle. Link to comment Share on other sites More sharing options...
Lucky Phil Posted July 13, 2021 Share Posted July 13, 2021 11 hours ago, Grim said: I like the shiny blue banjo... On pre-pump in tank bikes the hose has to bend round the fliter at a wired angle too, so it hits the airbox at an angle. Yes mine doesn't have that now. I spaced the regulator up a few extra mm so the vent hose now runs under it and has a straight shot at the airbox. You can just see it in this image passing under the regulator and fuel filter. Ciao 1 Link to comment Share on other sites More sharing options...
gstallons Posted July 16, 2021 Share Posted July 16, 2021 The way it goes with this crankcase shit , as with most MG , they sure have a screwed up concept going on . The way I see it , the frame rusts inside , cheap-ass rubber hoses , and a special place for all the rust to go : THE oil pan . Oh , did I forget , I don't remember a vent to atmosphere ? Link to comment Share on other sites More sharing options...
Lucky Phil Posted July 16, 2021 Share Posted July 16, 2021 6 minutes ago, gstallons said: The way it goes with this crankcase shit , as with most MG , they sure have a screwed up concept going on . The way I see it , the frame rusts inside , cheap-ass rubber hoses , and a special place for all the rust to go : THE oil pan . Oh , did I forget , I don't remember a vent to atmosphere ? In practice it's not generally as bad as you think. A vent to atmosphere has been illegal for probably 40 years or more due to emission regs so it feeds to the airbox to be burned. Ciao Link to comment Share on other sites More sharing options...
gstallons Posted July 16, 2021 Share Posted July 16, 2021 It could be different .......... Link to comment Share on other sites More sharing options...
docc Posted July 16, 2021 Share Posted July 16, 2021 15 minutes ago, gstallons said: It could be different .......... My GB's closed venting would oil contaminate the air filter ridiculously. It went "atmospheric" long ago . . . > Watch yer eyes! < 1 Link to comment Share on other sites More sharing options...
Lucky Phil Posted July 16, 2021 Share Posted July 16, 2021 27 minutes ago, gstallons said: It could be different .......... Venting the crankcases into the airbox is perfectly rational. It's been done on WSB engines for at least 35 years. Generally only an issue if your engines got ring seal problems or the original design was really bad or you've taken a pedestrian grocery getter engine and tried to make it a race engine. Ciao Link to comment Share on other sites More sharing options...
Lucky Phil Posted July 16, 2021 Share Posted July 16, 2021 14 minutes ago, docc said: My GB's closed venting would oil contaminate the air filter ridiculously. It went "atmospheric" long ago . . . > Watch yer eyes! < Haven't you just had the engine rebuilt docc? No need for this if the rings seal well. where did the original hose vent to in the airbox? surely on the engine side of the filter. Did it have a reed valve in the original vent line? Ciao Link to comment Share on other sites More sharing options...
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