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Post by cyburban on Jul 10, 2021 10:47:19 GMT -5
Hello, Yesterday I installed a 70cc big bore kit on my 2007 tgb key west. It has a Morini engine. I got it running and have started breaking it in but I am having a couple tuning related issues. Full setup is - 70cc big bore kit Stock mikuni carb with upjet to 75 stock airbox technigas next r pipe
I have two issues -
1. When I let off the throttle at speed, the scooter seems like it has "cruise control" and won't decelerate like before the kit. I can get around this by braking and jiggling the throttle but it doesn't naturally want to fall back to idle. I really have no idea where to start with this. I did have to play with the idle screw and the throttle cable adjustment to get it to idle but at idle its not spinning the back wheel or anything crazy.
2. When I give it a lot of throttle, it kind of falls on its face and then it picks up and goes. My guess is that I need to drill a couple holes in the stock airbox to give it more air to balance out the mixture with the 75 upjet but I am not super experienced with this sort of thing.
Any idea are appreciated. TIA!
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Post by captincvmn on Jul 10, 2021 11:27:53 GMT -5
When you say you adjusted the throttle cable to help set idle that’s concerning. The idle mixture screw and the idle speed screw should be used not the adjustments on the cable length. The cable length adjustments should be for making sure the slide absolutely has a wee bit of slack to return to idle and/or making sure you get 100% open throttle at the other end.
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Post by cyburban on Jul 10, 2021 12:34:37 GMT -5
When you say you adjusted the throttle cable to help set idle that’s concerning. The idle mixture screw and the idle speed screw should be used not the adjustments on the cable length. The cable length adjustments should be for making sure the slide absolutely has a wee bit of slack to return to idle and/or making sure you get 100% open throttle at the other end. Yeah, that makes sense. I think I have way too lean of a jet in it. Adjusting that cable so it’s basically getting throttle to idle is not right at all.
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dioarmy
Scoot Junior
brappppppppppppp
Posts: 9
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Post by dioarmy on Jul 17, 2021 1:07:40 GMT -5
start at 102 jet, or you will soft seize.
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Post by Zino on Jul 17, 2021 6:54:15 GMT -5
It is wrong when your Throttle cable adjustment is changing your idle . Up by the handle it is mainly for removing slack so you have quicker throttle response . Down by the Carb like Captain says it is set so it bottoms out for minimum idle and it opens all the way at full throttle.
Jetting keep it simple . Dont drill holes in your air box you would be adding another variable GO bigger on the Jet first till it gurgles at full blast and then work your way down to the richest jet that gives you the best top speed . Then adjust the needle for the one with best throttle response that is the richest at 1/4 to 3/4 throttle. And then dial in the idle jet for best transition to 1/4 throttle
CVT Tuning You added a expansion pipe that makes power higher and in a narrower range than stock . It needs lighter variator weights than stock and stiffer clutch springs If you are rolling slow for 10 meters and then picking up speed you need stiffer springs ,Usually medium or hard gts you in the right place . For variator weights You can buy a tuning set off amazon find the best weights and then buy sliders or rollers at that weight .
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