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Post by geh3333 on May 31, 2015 21:55:34 GMT -5
What kit ,did you buy ? What size carb ?
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Post by ricardoguitars on May 31, 2015 22:35:28 GMT -5
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Post by geh3333 on Jun 1, 2015 0:30:32 GMT -5
Sorry , but I don't remember if you already have a high performance exhaust and air filter mod ? I'd wait until you get all the other mods done before installing the bigger carb. I'd say a 120-125 main jet should work out pretty good when all is said and done . |
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Post by ricardoguitars on Jun 1, 2015 9:47:22 GMT -5
Sorry , but I don't remember if you already have a high performance exhaust and air filter mod ? I'd wait until you get all the other mods done before installing the bigger carb. I'd say a 120-125 main jet should work out pretty good when all is said and done . I got rid of the airbox a long time ago, the exhaust is supposed to be a "performance exhaust", I bought it locally, I didn't noticed any difference on the performance when I installed it, it just got a little louder. Those BBK are usually 155cc right? My scoot is a 125cc, so I believe I will get a noticeable difference, let's see  Not sure if I will need a bigger piston rod, I know on a 150cc you can use the stock one, not sure if it is the same size on a 125cc  |
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Post by geh3333 on Jun 1, 2015 13:17:21 GMT -5
Yep, its a 155cc . the crank should be fine. Displacement is one thing but horse power is another. You can have a displacement of 155cc but without the extra air and fuel your not going to notice too much of a difference. That's where the exhaust , air filter, carb , advanced timing, performance head , bigger intake, etc , come into play. If done right horse power can Be more effective then displacement , however both together is what you want. For example , I went from 57mm to a 58.5 which isn't much . if I would not have done all the other mods I would not have noticed much. Even a 61mm with a stock exhaust and stock air filter , you would not notice much of an increase in performance. You can get a stock bore 150cc to do close to 65mph with the right mods . you hear of some with a 63mm kit that still cannot reach the 70mph range. You hear some say there is no replacement for displacement , however there is , and that's horse power.
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Post by ricardoguitars on Jun 1, 2015 22:20:46 GMT -5
I haven't had the chance to check the needle, work is getting in the way of my wrenching  But I noticed today that it is going farther on RPMs than yesterday, maybe it just need to break in a bit, now I can reach 6k, a whole lot more responsive, I can even pass some cars on the street, I couldn't do that before with the old carb, acceleration is great, but it tops at 80kmph (optimistic chinese speedo readings), it used to top at almost 110kmph (again, optimistic chinese speedo readings); it is guzzling fuel though, lol.  When it tops at 6k RPM, it feels like if the brakes where applied a bit randomly. |
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Post by geh3333 on Jun 1, 2015 22:23:57 GMT -5
Was it cooler out today ?
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Post by ricardoguitars on Jun 1, 2015 22:24:49 GMT -5
Was it cooler out today ? Almost the same, but a lot more humid. |
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Post by geh3333 on Jun 1, 2015 22:32:16 GMT -5
Was it cooler out today ? Almost the same, but a lot more humid. I think you will really like the performance of the bigger carb after all the mods are done . its nice to be able to pass cars if you want or have to. |
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Post by chromestarhustler on Jun 4, 2015 21:30:32 GMT -5
personally the 30mm carbs have never worked for me, i have tried a couple on several different scooters, since they work off constant velocity, and the max volume is pretty much decided by the engine size and rpm. at high rpms the engine can not draw more air in order to push up the slide and raise the needle for more fuel, by increasing the diameter or the bore the slide has to raise less in order to feed the same volume of air, almost anytime i see a 30mm work was when someone had a carb adjusted for crap, and going to a well adjusted stock carb increases throttle response and drive-ablity and power.
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Post by geh3333 on Jun 5, 2015 1:32:44 GMT -5
personally the 30mm carbs have never worked for me, i have tried a couple on several different scooters, since they work off constant velocity, and the max volume is pretty much decided by the engine size and rpm. at high rpms the engine can not draw more air in order to push up the slide and raise the needle for more fuel, by increasing the diameter or the bore the slide has to raise less in order to feed the same volume of air, almost anytime i see a 30mm work was when someone had a carb adjusted for crap, and going to a well adjusted stock carb increases throttle response and drive-ablity and power. They tend to be harder to tune . I actually cut a coil or so off of the plunger spring , I kept the pilot in that came with my 32mm carb and I went with a 125 main jet. I can get my scoot to idle even under 1500 rpms , as low as 1300 rpms without stalling. I had a member try a cheap 30mm carb with no luck , no matter what size jet he used . finally the shop that he took it to said the carb must be defective , as I would imagine many of the cheap branded carbs are. He bought a 28mm mikuni racing carb and used a much bigger main jet then was even tried in the 30mm. He had a 61mm gy6 200 from scrappy. It was acting rich even with a 115 main jet with the 30mm carb. His 28mm mikuni racing carb took an equivalent of a keihin 140 main jet , If I remember correctly. These bigger pumper carbs can def be a pain to tune . I believe the pump can even be adjusted for when it squirts the extra fuel in. I have great throttle response now and great power throughout the throttle range . this also has a lot to do with the CVT , so I cannot say the carb is the only reason for this. I had a little slower takeoff when I had the cheap koso variator in . it would not let my belt drop in the variator , which slowed takeoff down a little . actually some setups may not be able to take the bigger carb . its just strange to me , considering I have a small 58.5 bbk and my 32mm pumper carb seems to be a perfect match for it. Of course I have a nice head also . I'd like to get ahold of one of the scoots that don't seem to be able to handle the bigger carbs and see if I could figure out why . |
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Post by chromestarhustler on Jun 5, 2015 12:32:20 GMT -5
i liken it to sticking a 1050 dominator on a stock 305 over carbing it only helps at high rpm WOT when your undercammed or have a poor flowing intake/heads, using bernoulli's principle the decrease in velocity would increase intake tract pressure allowing a force fill, but velocity is the preferred way to fill the cylinders.  percent of us just cant make good use of the extra flow potential, some of it may have to do with air density differences, here at 5400 ft above sea level we only have approx 80 percent of the oxygen that sea level does and our air density is well about equally bad. Typically 57-60 miles per hour is the top speed I can tune a stock scooter to, but on a good high pressure day thats slightly cool when a storm front is pushing thru i can sometimes hit 62-65, which for a stock scooter is probably as good as its ever gonna get. well its not like these scooters are anywhere near standardized, i was comparing 3 heads the other day, to set on top of my new high compression 58.5 BBk, one head had a much smaller volume cc head, but the valves were shrouded thanks to this tight head, so wont breath as well but will give higher compression, but its intake tract was also the nicest smoothest as cast intake port i ever seen, which should have good flow, the others had a very nice plain dome and unshrouded valves that should flow well, but the intake tract looks like the rocky mountains at the transition areas. now i know the scooters these heads came off, both ran damn well....chinese variance...the bastards, now i gonna go sit somewhere and decide which one to use. |
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Post by ricardoguitars on Jun 6, 2015 20:03:18 GMT -5
Today I hit 8k RPMs on the highway without too much effort, 120kmph Chinese speedo reading, I haven't done anything to the carb since I installed it and did the basic tuning, this thing gets better with time, I guess the needle was stuck for being stored on a shop shelf for who knows how long and now it got loose, the fuel consumption got better too. I can't way for the BBK and the head to arrive, I'm creating a monster!! buahahahaha...!!  |
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Post by tvnacman on Jun 7, 2015 9:05:11 GMT -5
what did you do with the extra vac hose?
John
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Post by ricardoguitars on Jun 7, 2015 10:31:07 GMT -5
what did you do with the extra vac hose? John I removed the 3 way hose junction and plugged the vacuum hose straight from the petcock to the intake manifold. |
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percent of us just cant make good use of the extra flow potential, some of it may have to do with air density differences, here at 5400 ft above sea level we only have approx 80 percent of the oxygen that sea level does and our air density is well about equally bad. Typically 57-60 miles per hour is the top speed I can tune a stock scooter to, but on a good high pressure day thats slightly cool when a storm front is pushing thru i can sometimes hit 62-65, which for a stock scooter is probably as good as its ever gonna get.
