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Post by paulgendek on Aug 13, 2013 9:49:12 GMT -5
So I originally went all the way up to 110 main jet after all my mods to figure out why I wasn't getting any top speed. I have the 4g sliders in now, so I'm getting into the ~7500 RPM area. Things were running great, buck sucking away all of my gas. Yesterday, I downjetted to the  to try to balance the power with fuel efficiency. I noticed that I would get this really awesome speed boost, even uphill, at around 7200-7500 RPM, but the problem is that I can't always get up to that RPM, sometimes it bogs and won't pass 7000. What causes that speed boost? How can I make it happen consistently? What upgrades/mods should I do? Why does it bog at 7000 sometimes, but sometimes go up to 7500/8000? Should I upjet back to something like 100 or 105? Thanks in advance! |
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Post by jeffery5568 on Aug 13, 2013 10:03:06 GMT -5
I would try a 100
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Post by millsc on Aug 13, 2013 10:09:47 GMT -5
I suggest putting the airbox back on removing the front cap on the snorkle and run a 82-  jet I had the same mods and same scooter you have and mine ran best this way prior to the big bore kit |
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Post by paulgendek on Aug 13, 2013 10:32:50 GMT -5
We're also in two very different climates
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Post by millsc on Aug 13, 2013 10:40:47 GMT -5
I can almost quarantee if you put that airbox back remove the front cap leave all other restrictors and put in a jet it will run awesome, my cy50a wouldn't run with an open air filter without huge jets either before the big bore kit and ran worse than it did with airbox and smaller jet been there done this |
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Post by millsc on Aug 13, 2013 10:43:58 GMT -5
my cy50a its where it all began for me Attachments:
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Post by paulgendek on Aug 13, 2013 10:45:04 GMT -5
I'm going to go back up to 100 first, then I'll give the airbox a try for sure, thanks.
Saw something in another thread about putting some holes and PVC with Uni filter material in airbox, sounded reasonable.
Still curious about the technical happenings in my original post though. What causes the boost, why it won't consistently go over 7000 rpm, etc?
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Post by millsc on Aug 13, 2013 10:50:42 GMT -5
what happens is the hipro exhaust doesn't create enough back pressure without a bigger motor. And you are putting too much too air in and out for the small 39mm piston, so you have to feed it tons of fuel to get it to even run reasonably good. You went to far with mods for the small motor got to cut some of the air or upgrade the engine with a big bore kit, i did the exact same thing you did.
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Post by millsc on Aug 13, 2013 10:51:54 GMT -5
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Post by brandjur on Aug 13, 2013 11:29:49 GMT -5
The power surge isn't consistent because you are running into 2 things.
1. The limitations of the stock motor with stock camshaft
2. Too rich of a main jet will bog the the engine and when the spark plug can burn some of that fuel off, you get the rush.
Like in your last thread, I asked how is your spark plug looking? Have you done any plug chops? If you don't go through the #1 way we determine the correct range for main jets, then you are just going to be guessing. The best way to know what is going on inside your engine is to go inside.
What you need is a big bore kit and A9 camshaft. You have maxed out your engine and it would be a waste of time and money to try to push it more. Remember, we look for consistency and durability in power delivery. That's why we bolt on the big bore kits.
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Post by millsc on Aug 13, 2013 11:53:17 GMT -5
Either cut some of the air by removing the open air filter, take off the hipro exhaust or put a big bore kit on it. I choose to put a big bore on mine. Inflating the scoot with all that gas with huge jets isn't economical and a waste of time and money for less performance
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Post by paulgendek on Aug 13, 2013 12:10:15 GMT -5
I'm having a great time modding this thing, so how hard is it to put a BBK/A9 on? Same as most of the other stuff? Typical garage tools? In the meantime, I will probably try what I said above already. I don't drive this thing to work or anything, it's just for fun  |
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Post by brandjur on Aug 13, 2013 12:20:16 GMT -5
I'm having a great time modding this thing, so how hard is it to put a BBK/A9 on? Same as most of the other stuff? Typical garage tools? In the meantime, I will probably try what I said above already. I don't drive this thing to work or anything, it's just for fun  Yes, typical garage tools. Thats it. The only thing you would need to purchase is a feeler gauge, but you would need that anyways to check the valves. It is a LOT more fun when you get the torque from the big bore kits. Again, check your spark plug. |
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Post by millsc on Aug 13, 2013 12:21:16 GMT -5
its not hard to put on the big bore kit i don't even take out the motor just the seat and plastic under the seat
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Post by millsc on Aug 13, 2013 12:23:44 GMT -5
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to try to balance the power with fuel efficiency. 
main jet
MJ, Orange coil, Blue Performance CDI (Orange NCY did not work), NGK Iridium, 5g Sliders