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Post by magoconnor on Jun 22, 2017 17:02:25 GMT -5
Hi!  I hope you guys can help me out! I've got some problems with my new 72cc Cyllinder kit. My main problem is that I have lost top speed. The scooter runs okay ( starts up everytime, and idle's perfectly) Right now the top speed is about 60kh on the gps (37mph) My current setup: Kymco super 8 4t 72cc kit Sport camshaft Portmatched the intake and exhaust. leovince exhaust Stock carburetor 85 main jet Racing clutch 1500 rpm springs, stock torque spring Polini speed control variator 4,9 g Stock air filter. Removed the SLS system. Removed all restrictions. |
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Post by jaga4life on Jun 23, 2017 6:49:01 GMT -5
I have had very good luck running a 95 main jet, with a open air filter. You have to tune the carb. Top speed on my 47mm kit was 44 45. Stock cvt. How's the acceleration. Any type of bog or does it seem to fall on its face anywhere in the power band? An 85 jet should be fine but you have to tune the carb to the engines liking.
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Post by 90GTVert on Jun 23, 2017 7:57:48 GMT -5
 You lost speed with the installation of the kit or you installed the kit and it went faster and then you lost speed?
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Post by magoconnor on Jun 23, 2017 11:26:06 GMT -5
Hi.
I have just received a 21mm carburetor today, with 92 main jet.
The acceleration is good, up till about 50 kh (31mph)
I will try and swap out the 4,9g for 5,5.
And I will swap the stock air filter for a malossi red sponge.
I installed the 72cc kit and lost speed.
Any other thoughts, of what might be the problem?
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Post by magoconnor on Jun 25, 2017 22:23:09 GMT -5
Anyone?
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Post by humanshield on Jun 26, 2017 11:12:20 GMT -5
Sound can help diagnose the issue. If we could HEAR the engine as you ride it and accelerate we might be able to tell from the sound.
You "might" have a sticking clutch.
You "might" need a new variator and or rollers.
You "might" have the timing off a tooth
You "might" need to up the MJ a size or two
But I would check the variator and clutch first
BTW...."losing" speed when you install a BBK is not uncommon. Why? Because you have fundamentally changed the breathing dynamics of the engine. You have to compensate for the increased airflow.
That can be a painful process even for advanced tuners.
Don't get frustrated....just take your time and realize it could take a good bit of work and changes to get it right.
Know that when you do,....you'll be glad you put the effort in.
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Post by magoconnor on Jun 27, 2017 18:31:35 GMT -5
Hello again. I have installed a 90 main jet (still using the stock carburetor) and a malossi red sponge air filter. And 6,9 g rollers. The bike is able to hold idle (sometimes) but when I let go of the throttle, it just dies out. I have tried to play aorund with airfuel screw unsuccesfully. I pulled the plug, right after the video/audio clip below. White center, rest of it black! here is picture. Lean? I check the timing again, seems fine. Something is definitely wrong. The run I did in the video, is full throttle! Sort of bad acceleration, completely dies at around 24mph and is unable to gain any more speed. It sputters alot from about 20-24mph. Funny enough second run i did, i was able to get it up, to around 30 mph. Here is a audio/sound clip, Hope you can help me out. www.youtube.com/watch?v=SWKjIMzbT-s |
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Post by magoconnor on Jun 29, 2017 19:52:15 GMT -5
Anyone??? Could really use some help.
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Post by scott7 on Jun 30, 2017 6:22:47 GMT -5
Looks pretty rich to me with only using 90 jet , I would check and make sure the electric choke is working correctly and also make sure there is no fuel getting into the vacuum line from the fuel valve, also check for vacuum leaks.. Also the mid range needle jet may need adjusting
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Post by AtariGuy on Jul 1, 2017 21:25:50 GMT -5
Theres a thought, if your vacuum petcock blew a diaphragm, you could be getting fuel flooding your carb. Lots of us replace the petcock with a manual fuel shutoff. Try that?
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tito
Scoot Member
confused, very confused
Posts: 32 
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Post by tito on Jul 12, 2017 7:36:41 GMT -5
Man this is why Im definitely not trying to do this stuff myself, I would have absolutely no clue where to start if everything didnt just work perfectly after bolting on, which from what im reading and hearing never happens.......ever. I have the same scoot though so would love to hear your upgrades and results as well as any advice as to what DOESNT work on our bikes.
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Post by humanshield on Jul 12, 2017 8:04:25 GMT -5
Man this is why Im definitely not trying to do this stuff myself, I would have absolutely no clue where to start if everything didnt just work perfectly after bolting on, which from what im reading and hearing never happens.......ever. I have the same scoot though so would love to hear your upgrades and results as well as any advice as to what DOESNT work on our bikes. but...but...everyone has to start somewhere.... Nothing ventured, nothing gained they say. Just read about how carbs work. eventually everything comes together and its not so scary  |
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Post by benji on Jul 12, 2017 12:10:55 GMT -5
Man this is why Im definitely not trying to do this stuff myself, I would have absolutely no clue where to start if everything didnt just work perfectly after bolting on, which from what im reading and hearing never happens.......ever. I have the same scoot though so would love to hear your upgrades and results as well as any advice as to what DOESNT work on our bikes. but...but...everyone has to start somewhere.... Nothing ventured, nothing gained they say. Just read about how carbs work. eventually everything comes together and its not so scary This is true. It wasn't long ago that carburetors were a complete mystery to me, let alone jetting and air/fuel ratio and how important it was(some may say it still is a mystery to me haha). It starts to make sense eventually. |
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Post by benji on Jul 12, 2017 12:16:26 GMT -5
what DOESNT work on our bikes. Just replacing stuff doesn't usually work. You may have to learn some new skills, as these aren't typically "replace and check" style parts. Usually you have to tune or adjust something, or figure out what is causing whatever issue pops up. |
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tito
Scoot Member
confused, very confused
Posts: 32
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Post by tito on Jul 15, 2017 17:41:44 GMT -5
what DOESNT work on our bikes. Just replacing stuff doesn't usually work. You may have to learn some new skills, as these aren't typically "replace and check" style parts. Usually you have to tune or adjust something, or figure out what is causing whatever issue pops up. Yeah thats a little scary right now, Ill have a very experienced certified mechanic coming by to install, tune and troublshoot for me. Im reading and watching as much as I can with almost 100% of my free time so I will hopefully be able to learn as I go. I cant even say how helpful this forum and the forum creators youtube channel has been for me, he answers every question I have and has a zillion scooter diy videos for people to learn, he is one crafty dude. Some of the techniques he uses to help people avoid buying specialty tools to use 1 time are quite impressive. |
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