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Post by Fox on Jul 29, 2015 11:18:41 GMT -5
The vent tube is also an escape tunnel for water vapor condensation, exhaust gas blow by from the combustion process, a small amount of oil and other toxic fumes. Having all that stuff recycle through the carburetor throat and on into the engine is a bad idea in my and many other's opinion for carb cleanliness reasons so years ago we here on the scooter internets came up with the idea of running the vent tube up the frame and having it vent toward the rear of the scooter. Even with good new piston rings there is going to be some blow by. Water vapor condenses in the crankcase. Nothing you can do to get around that and like I said, all that crap can and will gunk up the carburetor. There's a thread in the tech section here where I got the picture of one of Brent's scooters below. 49ccscoot.proboards.com/thread/997/crankcase-ventingThe uphill slope of the tube helps prevent oil loss.  |
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Post by derbiman on Jul 29, 2015 13:45:33 GMT -5
Fox,I like the fact that the vent is open in the picture, but all of the water vapor will condense in the cooler tube and run downhill back into the engine especially after the engine is turned off. I would run mine downhill to expell any water in the tube. I think the vapor would be less likely to damage the engine than to have distilled water drops run into the crankcase.Just my 2 cents.
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Post by Fox on Jul 29, 2015 13:58:15 GMT -5
Well I'm not concerned about that tiny bit of water in the crank case because it's not going to hurt anything and even with an insulated hose it's still gonna condense inside the engine case so why fight it? I'm way more concerned about water vapor and other contaminates such as motor oil and combustion gasses getting spewed all over the carburetor throat and into the air passages at the rear of that throat gumming up the carburetor. Whatever you like to do with your personal scooter is fine with us here at the 49ccscoot family derbiman. I have done this mod to many many scooters over the years some mine and some customers scoots. I always run the tube up the frame and then back downhill and let it vent out at the bottom of the rear mud guard as represented by the yellow line in this picture. The tube is on the inside of the mud guard so it's not visible held on by two small-ish black zip ties that required 2 sets of 2 small holes drilled along the left edge of the mud guard. That was my very first scooter.  Actually what gave me the idea of this mod back in 2006 was the air filter on the scooter in the above picture. They had the vent tube routed to the intake snorkel on the air filter cover so the gasses were getting shot all over my filter element. I rode at WOT for long periods sometimes and these gasses were so hot they actually melted the filter element partially and the filter was always filthy. On renegade's setup these gasses are getting thrown directly onto the carb. Not good in my opinion. The tube hooked to the airbox here:  My melted air filter:  The replacement filter after vent tube modification and a couple months riding around town:  |
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Post by derbiman on Jul 29, 2015 14:35:27 GMT -5
I am not trying to make waves, I was simply pointing out that the vent tube is actually working just like a still. I do however, like the mod you did on the filter box. BTW,I hope your recovery is going well.
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Post by Fox on Jul 29, 2015 14:52:47 GMT -5
I didn't take it like that. Your point is valid and something that I never really thought about. My recovery is going to plan. I am just doing the leg machine and spending a lot of time online here. Without the forum I would be bored out of my mind. I figured out a way that I can do the leg machine while I surf the web. It includes two 5 gallon paint buckets and an adjustable office chair. I will have my GF take a picture later and post it.  What I meant to include before and forgot to mention was that I personally feel that by introducing anything other than clean fresh air into the combustion process makes that process less efficient. I may be wrong but instinct tells me that any by-products in there will make the fuel burn less efficiently so it's more than just keeping the carb clean. Maybe something like this would be a solution? I don't know. It would have to be drained periodically. More maint...  |
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Post by usmcdoc on Jul 29, 2015 14:54:20 GMT -5
What I have done for several 150cc scoots..since they seem more prone to this is is shown in the following link. Works for 50cc engines as well. Mount it higher than the valve cover of course..so it will drain back. As mentioned by a few..they were concerned the steel wool particles would get inside the engine..so I bought a 2 pack of the copper 'chore boys' at the dollar store and they actually work better..because they allow greater airflow due to the size of their mesh.. Here is the link..double click the pic to make it large enough to see... 49ccscoot.proboards.com/search/results?captcha_id=captcha_search&what_all=hamster+bottle&who_only_made_by=0&display_as=0&search=Search |
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Post by derbiman on Jul 29, 2015 15:02:12 GMT -5
Glad all is going well, Fox. I am recovering from shoulder surgery and this forum is the only thing keeping me sane. Lol
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Post by Fox on Jul 29, 2015 15:13:39 GMT -5
Most of the 150's have this type of setup that requires draining the catch tube from time to time and the fumes get recycled through the carb. The collected liquid is some of the foulest smelling stuff btw... Stupid design cause when it fills up it overflows and that crap gets all over the engine and tire etc... most people don't even know about that tube so it never gets emptied. Of course there is a small cover that is removed in the picture.  |
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Post by derbiman on Jul 29, 2015 15:25:13 GMT -5
I like that set up. At least the solids go down and the by products can not go through the carb.
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Post by usmcdoc on Jul 29, 2015 16:01:12 GMT -5
Well I'm not concerned about that tiny bit of water in the crank case because it's not going to hurt anything and even with an insulated hose it's still gonna condense inside the engine case so why fight it? I'm way more concerned about water vapor and other contaminates such as motor oil and combustion gasses getting spewed all over the carburetor throat and into the air passages at the rear of that throat gumming up the carburetor. Whatever you like to do with your personal scooter is fine with us here at the 49ccscoot family derbiman. I have done this mod to many many scooters over the years some mine and some customers scoots. I always run the tube up the frame and then back downhill and let it vent out at the bottom of the rear mud guard as represented by the yellow line in this picture. The tube is on the inside of the mud guard so it's not visible held on by two small-ish black zip ties that required 2 sets of 2 small holes drilled along the left edge of the mud guard. That was my very first scooter. Actually what gave me the idea of this mod back in 2006 was the air filter on the scooter in the above picture. They had the vent tube routed to the intake snorkel on the air filter cover so the gasses were getting shot all over my filter element. I rode at WOT for long periods sometimes and these gasses were so hot they actually melted the filter element partially and the filter was always filthy. On renegade's setup these gasses are getting thrown directly onto the carb. Not good in my opinion. The tube hooked to the airbox here: My melted air filter: The replacement filter after vent tube modification and a couple months riding around town: Scoots these days have the vent tube plugged into the intake after the air filter. Such as the OP scoot here does. So it does not plug the air filter. Also ..vapor and fumes from the valve cover vent tube ONLY pass through the Venturi of the carb. They are nowhere near any of the internal passageways..main jet or pilot jet even. So recirculating the valve cover gases will in no way affect the carb by getting it dirty and clogged up. If that was the case..our cars would never get 250,000+ miles as they do these days now..because the EGR ventilation on those goes right into the throttle body..then into and through the intake plenum. As ya know a throttle body is the same as a carb body..except the fuel is metered electronically vice with carb vacuum. Which will bring up another point that I am sure you as well..chuckle at when ya see it. Folks will spray aerosol carb cleaner into the carb venturi only..rev the engine a few times..and then say they just cleaned the carb..  NOTHING can contaminate..NOR clean a carb if it only goes through the venturi. Hell that thing is just a big hole.. Contaminants and cleaners must get inside the carb..so the carb has to be removed and completely disassembled for either to affect them.. Well..or if they don't use a fuel filter..garbage can contaminate the carb.. |
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Post by Fox on Jul 29, 2015 16:09:51 GMT -5
Sorry doc but if you look at the back of a carb you would see there are small venturis and a section on top of the throat that leads to the diaphragm chamber. If you blow into that section the diaphragm will move up. I have a Mazda with a fuel injected V-6 and the throttle body gets plenty dirty inside. I clean it every so often. It gets black crap all over it.  |
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Post by scooterpimp on Jul 29, 2015 16:20:14 GMT -5
Here's my 2 cents , i prefer to have vacume to pull moisture , excess fumes etc. & reburn it. Vs a tube open etc. Leaving contaminated crap to sit . see a car without a vacume source to breather? Not me unless its antique or racing setup.  our modern gasoline will cause more harm then vented breathers. Gumout will clean carb /throttle body bores easily , but ethanol damage isnt cleanable. |
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Post by usmcdoc on Jul 29, 2015 16:46:22 GMT -5
Sorry doc but if you look at the back of a carb you would see there are small venturis and a section on top of the throat that leads to the diaphragm chamber. If you blow into that section the diaphragm will move up. I have a Mazda with a fuel injected V-6 and the throttle body gets plenty dirty inside. I clean it every so often. It gets black crap all over it. Ok..you win. As always..you just HAVE to negate everything I post and be right Sir. So then right you are.. Like Burger King.."Have it your way" Smile..you win..I lose..even though I am right..you can have this one and every post I make. Bothers me none.. Have a nice day..  Just for your entertainment..I am going to make another technical post..that way you have more stuff to negate.. |
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Post by usmcdoc on Jul 29, 2015 16:48:59 GMT -5
Here's my 2 cents , i prefer to have vacume to pull moisture , excess fumes etc. & reburn it. Vs a tube open etc. Leaving contaminated crap to sit . see a car without a vacume source to breather? Not me unless its antique or racing setup. " style="max-width:100%;"] our modern gasoline will cause more harm then vented breathers. Gumout will clean carb /throttle body bores easily , but ethanol damage isnt cleanable. I agree Sir..but you will told you are wrong.. The system was designed the way it was on Scoots for a reason.. It was designed by Engineers to be setup as you described..for that reason.. But sorry that you and I are both wrong anyway.. lol.. Hey sh*t happens..  |
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Post by Fox on Jul 29, 2015 17:27:46 GMT -5
Who said the designers were spot on? These friggin' vents are routed the way they are for emissions reasons, not for optimal performance and not for reliability. If you prefer to have black nasty crap spewing into your carb and engine then great, knock yourself out!
If you prefer to have your air filter stay cleaner longer, your carburetor stay in tune longer, decrease maint. intervals, remove contaminates from the combustion process and make your scooter more reliable then modify the vent line so it doesn't spew that crap into the air filter or carburetor. That's my point. That's all I'm trying to say. You can spin it any way you want to but the bottom line for me is that Brent himself thinks it's a good idea so much that he did it to his scoot and 100% of the time I trust his judgement over my own when it comes to scooter anything. This Mod is meant to make the scooter less likely to leave you stranded if you think long and hard about it.
Lastly, on the ethanol subject: These are cheap Chinese scooter engines. Glorified lawn mower engines. They aren't supposed to last forever. If you get 3-4 years of service out of one you did well and then you go buy a new one or a used scooter with low miles and swap engines. We can sit and think everything to death but you can't stop corrosion and time from taking it's toll and at about the 2 1/2-3 year mark a well-ridden scooter will start to experience failures of the wiring, switches, cables, the front shocks, calipers/brakes and even the plastics start failing and they become a money pit.
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Just for your entertainment..I am going to make another technical post..that way you have more stuff to negate.. 