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Post by geh3333 on Jun 15, 2015 10:47:57 GMT -5
Well from what I read , the head is not considered into the cc's of the engine. The cc of the combustion chamber however , is used for compression ratio. It only makes sense that the bigger the combustion chamber the more air and fuel can enter on downstroke. May not be much more but it still would be more . so everyone who is running a stock head with a bbk , your loosing out on performance. Not only with better quality but a smaller combustion chamber which would cause you to not be able to burn as much fuel .
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Post by geh3333 on Jun 15, 2015 10:29:42 GMT -5
The more I think about these calculations , the more I have issues with them . well at least some parts. Like , shouldn't the piston pull in at least the amount of air and fuel to equal the cc of the bore ? Well considering the rings are sealed good , I would expect yes. The more I look at my calculations I come to understand that when it comes to my setup , I am pulling in the perfect amount of fuel to match the amount of air in my chamber. When it comes to a stock setup with  mpg . the amount of fuel the setup is pulling into the chamber only needs 77cc's of air to burn it. So this would be a lean condition. The part that really gets me is , how then is someone with a stock bore able to not run lean and still get or even 80 mpg ? I did these calculations not having a clue how they would turn out , and when it comes to my setup , it seems I'm running the perfect mixture . when I say perfect mixture , I mean I'm pulling in the perfect amount of fuel to match the amount of air pulled in by the 58.5 top end. I do have a question . when it comes to the cc's of the chamber . does the 155cc count the head chamber also ? When it comes to the amount of air and fuel being pulled into the top end , a bigger head size would allow in more air and fuel . I'm thinking it only counts the cylinder space . does anyone have the answer to this ? |
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Post by geh3333 on Jun 15, 2015 10:01:40 GMT -5
i checked mine with a lighter,,,no more tank,,no more problem,,,no more eyebrows either,,,,  ,,,,my vespa had a plastic insert,,,what a pain in the left nut,,,it was hard to get out but it was worth the effort PLASTIC ?? Wow. Removing that cross strap inside the filler is the single best mod I've done. Before, had to put gas in as slow as possible - trickling from the nozzle, and still it would at times splash. Now - stick the nozzle in, set it on "max", a few seconds later it shuts off. Then a few more squirts to top it off and outta there. Just don't cause a spark! Best: use needle nose pliers to twist it repeatedly till it pops off. ChinaSteel - not exactly the strongest stuff on the planet. You couldn't spray to the side of the bracket ? |
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Post by geh3333 on Jun 15, 2015 10:00:27 GMT -5
The pumps should turn off when the end of the nozzle become submerged. If you have the gas filler guard you will obviously be unable to put the nozzle into the hole because the guard stops it right at the opening, and therefor the pumps automatic shutoff may not be effective or work at all. Mine sits about 2 to 2.5 inches down into the hole . |
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Post by geh3333 on Jun 15, 2015 9:46:52 GMT -5
I think when the air fuel mixture gets sucked into the engine its pressurized right? this would alter the air density then What happens is on the downstroke the air and fuel is sucked into the chamber by the " downstroke of the piston in the cylinder" . same thing if you would suck something into a syringe . its not pressurized as its sucked in . then on the upstroke , both valves are closed Anthe the piston compresses the air and the gas , then around tdc the plug fires and ignites the compressed mixture which forces the piston back down . the piston then rises as the exhaust valve opens letting The gasses escape through the exhaust. |
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Post by geh3333 on Jun 15, 2015 9:33:53 GMT -5
Ok ok, Just so theres no misinformation in my thread DO NOT at any time use a tool to strike the gas tanks filler stopper ( hand tool or powered device) in an attempt to modify a scooters gas tank! I havent driven a car in years. I did at one point more than a decade ago go through a very good Tractor Trailer school in Upstate Ny and drove a big rig for a living! Rigs use "fuel" and carry a few hundred gallons. I know that it takes something with a higher "flash point" like kerosene to act as an accelerant when one desires to ignite Diesal fuel. A lit cigarette wont work where a common road flare will. This has been fun talking bout' fire, but can someone verify that American Gas Station gas pumps have a "shut-off" or over-fill prevention device? I cant post a Web link from my phone. Can someone do that? Post a link to explain gas pump overfill technology in Merica? I mean, offer this option to possible discriminating scooter mechanics as they might desire this and NOT my modification. Thanks! Yes , all the pumps I've ever used have had the automatic shutoff . I had the pump spray so hard that the mixture of air and gas made the gas raise so quick that it would run out of the tank. The shuttoff device does not work fast enough when that happens. When it comes to the metal bracket inside the tank " the one you cut off " , I'm not sure why its there. I guess it could be for a fill point. Since the cap sits down inside the tank a bit , you would have to be careful how high you fill the tank . if you fill it too full , the cal will overflow the gas as you put it back on. The reason you cut the bracket out , was because gas would hit the bracket as you were pumping and spray back out at you right ? |
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FFWWAOOOMP!
by: geh3333 - Jun 13, 2015 20:01:27 GMT -5
via mobile
Post by geh3333 on Jun 13, 2015 20:01:27 GMT -5
If you can get the piston to stay in the cylinder you should be fine. Everyone I ever talked with about removing the piston from the cylinder said you must hone and use new rings. Yes you can take the chance , but others on the site found out for themselves , that usually doesn't work. The rings seat into a certain position during break in. So you must rehone and yes new rings if the piston is removed from the çylinder. If I'm not mistaken , Lain , didn't this happen to you before ? Or was it someone else ?
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Post by geh3333 on Jun 13, 2015 18:26:58 GMT -5
Did yours have an rpm tach ?
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Post by geh3333 on Jun 13, 2015 18:14:28 GMT -5
Just filled up today, I only have the uni filter, and my carb is not quite dialed in correctly but, am avg. 56.5 mpg over 162 miles and 3 fill ups. And I know you weren't asking but is costing $0.053 per mile And these calculations are using the mileage off my speedo and using Fuelly to calculate. Wow that thing is sucking fuel !! Is your speedo accurate ? |
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Post by geh3333 on Jun 13, 2015 11:58:30 GMT -5
Well you could just do what I did. A Pirelli in the back and an Avon Viper Strike up front.  (BTW, I also found that even though my front and rear tires were the same size, the rear rim was made for a wider tire to begin with.) Mine had the same size on front and back , so that's what I've been running . shinko makes a front tire for match the sr568 i think is an sr567. |
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Post by geh3333 on Jun 13, 2015 7:58:02 GMT -5
I forgot to cover my instrument cluster at work the other day and the sun was so hot that it distorted my Odometer numbers wheel so bad that the numbers no longer turn. The odometer is forever stuck on 2,870 miles unless I can replace the wheel. Can I buy just the odometer numbers or wheel separately or do I have to replace the whole instrument cluster as an assembly? Anybody know these things?
BMS Heritage 150.
Thanks in advance... Well one good thing is if you ever sale the scoot it will always have those miles on the engine ! And you will more than likely have to buy a whole new clutster. |
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FFWWAOOOMP!
by: geh3333 - Jun 13, 2015 6:37:59 GMT -5
via mobile
Post by geh3333 on Jun 13, 2015 6:37:59 GMT -5
I just turned the flywheel in forward rotation until I was sure oil was flowing. I don't like the idea of running with an open cover, too high chance debris or litter (this is Boston) will fly in and I won't be fast enough to remove before it gets thrown down the chain. I couldn't get my pump started until I cranked her over. What you could do is ,hit the kill switch and crank her over . that way she won't start but it will crank over enough so that you should be able to see the oil being pumped. |
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Post by geh3333 on Jun 13, 2015 5:17:17 GMT -5
Get the shinko 130/60/13 I think they are sr568 . very good tires !
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Post by geh3333 on Jun 13, 2015 3:37:27 GMT -5
I want every one to remember that I used the exact same calculations with pretty much my exact fuel consumption , and it shows how much more fuel I'm burning and not running too rich , no bogging at any throttle level and hitting what seem to be record speeds for a 58.5 modded scoot . this should give many something to really think about when it comes to how much air and fuel these things can really handle.
We can even use this method to possibly help others with tuning their scoots. Just throw me your average mpg and I can give you a ballpark number of how much fuel your chamber is handling per ignition stroke.
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Post by geh3333 on Jun 13, 2015 3:26:31 GMT -5
Now let's do a calculation of a stock scoot getting mpg and see how many cc's are being filled . again this is not 100% accurate but it should be pretty darn close. Let's make this easy . say your scooting at 42.5 mph at 5500 rpms and your scoot gets mpg . you ride for 2 hr's at a steady 5500 rpms. So 120 min at 5500 RPMS is 660,000 revolutions, and 330,000 ignition strokes. So 1 gallon of gas was used which is 3785.411 ml of gas. Divide 3,785.411 by 330,00 which is .01147 ml per ignition stroke. Now the air consumption. 9,000 gallons of air needed to burn 1 gallon of gasoline. So take 9,000 ÷ 330,000 ignition strokes is .0272727273 gallons of air which is 103.23 cc's now divide by 75% for gas density is 77.4 cc's . wow , now add the fuel amount which is .01437 cc's and we get 77.4 cc , lol. I would say maybe this isn't the right way to do this , but considering these 150cc scoots top out many times around 50mph or so , well this would not surprise me if they are only burning 77.4ccs worth or air and fuel. And considering our pal millsc is hitting 56 mph with a 52mm ( 88cc ) bbk , and is probably using the entire chamber for fuel consumption with the 24mm carb , well this only makes sense. You get a 50c scoot on a good day can hit 40mph . compared to a 150cc scoot that does 55 on a good day. Your tripling the cc's but only gaining 15 mph !! Its probably because these scoots come under carbed and under jetted with restricted airflow , and the chambers are screaming for more air and fuel. Even if we drop the mpg down to 80 or 70 , the amount of cc consumption will be much lower then 150cc . |
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mpg . the amount of fuel the setup is pulling into the chamber only needs 77cc's of air to burn it. So this would be a lean condition. The part that really gets me is , how then is someone with a stock bore able to not run lean and still get 
