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Post by willie678 on Jan 21, 2021 11:14:47 GMT -5
See how your full throttle responds on the road and then compare that too full throttle with a 86 Jet. Once you get good performance at full throttle, Then go to your needle and a/f screw.
Getting close?... Check you spark plug color and consider plug temps as well. Br7Hs-Br9Hs
Taking notes is nice...
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Post by willie678 on Jan 25, 2021 2:19:07 GMT -5
To get a ballpark on the needle hight I usually see how much power it has from a stand still and going to about or past half throttle. Too much power is lean and sluggish is rich. I have up gears so if I am rich It won't even take off, it will just gurgle.
Make sure engine is really warm to do final a/f tuning. Check spark plug after a little ride with varying throttle positions. Or do a long ride full throttle then cut engine quick and check color to get an idea on main.
Throttle should be smooth transition, if there is a dead spot the tuning is usually off.
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Post by tatertots on Feb 4, 2021 3:13:28 GMT -5
Hello! I'm back from my few week hiatus. Just some other parts in + had some free time to spare so here's a quick update with where I'm at. I drove around a little on the 84 main jet and that felt pretty fine. Only issue I had with it was on takeoff from 5-15MPH where there seemed ot be a bit of a dead spot. Seems like a A/F screw or CVT tuning thing I would need to try. On the other hand, I tried the 90 main jet and even after initial riding, the scooter was continuously bogging down from 20-25MPH at WOT. So backed down I went with the 84. I think I'm going to stick with that jet for now since that's the one that's given me the best performance and I don't have another similar jet size. Here's what the Spark Plug looks like:
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Post by willie678 on Feb 9, 2021 1:09:25 GMT -5
If you have a dead spot you probably need to adjust the needle height and/or the main jet.
You could try to lean the needle and richen the a/f screw to keep your plug color. If needle height still leaves a dead spot then i suggest trying 86 or 82 main jet. 90 Jet not gunna do anything...
What i have found is that it is trial and error of main and needle height to get the dead spot out...
It is the throttle position not so much the speed you want to factor... thats why its good to label your throttle positions.
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Post by willie678 on Feb 9, 2021 12:02:12 GMT -5
You could go run 4-5 kms at full throttle, kill the engine a break quick. Pull out spark plug and check color and see what color just the main jet gives. Similar to plug chop...
Right now your spark plug color is an average of all your settings, if your not running all throttle positions before checking, like right after a ride, it is giving you more a reading for your idle rather than your main jet.
If the needle height doesnt fix it then, How much power do you have at full throttle?? If it quite peppy, i would try 86, IF its just ok power you might try the 82.
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Post by willie678 on Feb 9, 2021 12:11:45 GMT -5
Your also working with a very finicky carb. Tuning the PHBG is like night and day... less prone to dead spots. I think its the throttle cutaway that not as balanced... But $$$ to upgrade to single throttle cable and choke, at least for the dellorto I use the Polini Jets for the PHBG they have each individual size from 80 to 90. Dellorto phbg vs Chinese Black Clone Carb Carburetor Scooters performance tuning mopeds www.youtube.com/watch?v=ThjplCAfq0MAbout to install this knock off dellorto from china. www.aliexpress.com/item/4001028242746.html?spm=a2g0s.9042311.0.0.27424c4d3SGmX2ps, i find the auto choke a pain, and having a manual choke can help with tuning cause you can simply just make it richer by hand. ________ You may want to also consider carbon fiber reeds in the future, The ones already in the housing is much better. I used alot of permatex 2-stroke on these things... also for bottom gasket. I also use permatex red for the exaust gasket, and even red spray a gasket for the head gasket.!!
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